Term
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Definition
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Term
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Definition
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Term
| State the law of conservation of charge |
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Definition
| Charge is neither created not destroyed. Charge is always conserved |
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Term
| Electrical property of insulator |
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Definition
| Non metals TH electrons are tightly bound. |
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Term
| Electrical conductivity of a conductor |
|
Definition
Metals
Delocalised electrons |
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Term
|
Definition
| The force between two charges is directly proportional to the product of their charges and indirectly proportional to the square of the distance between them. |
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Term
| Electrical field strength |
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Definition
| Force per unit charge experienced by a small positive test charge in that electrical field |
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Term
| Two assumptions for coulomb's law |
|
Definition
1. Two point charges
2. Separation is large |
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Term
| Newton's law of gravitation |
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Definition
| Force between two point masses is directly proportional to the product of their masses and indirectly proportional to the square of the distance between them. Given the distance is large in comparison with their radii |
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Term
| Gravitational field strength |
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Definition
| Force per unit mass experienced by a small point mass in that field. |
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Term
| Gravitational potential energy |
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Definition
| Work done per unit mass in moving a point mass from infinity to point P in a gravitational field |
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Term
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Definition
| Work done in moving a small positive test charge |
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Term
| Electrical potential energy |
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Definition
| Work done in moving a small positive test charge from infinity to a point p in the electrical field |
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Term
|
Definition
| In the absence of external forces a body at constant velocity or at rest will remain at constant velocity. |
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Term
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Definition
| Distance moved in a particular direction |
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Term
|
Definition
| Rate of change of displacement |
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Term
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Definition
| Rate of change of distance |
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Term
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Definition
| Rate of change of velocity |
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Term
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Definition
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Term
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Definition
| Total divided by total no |
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Term
| Outline conditions under which uniformly accelerated motion may be applied. |
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Definition
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Term
| Air resistance on falling objects |
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Definition
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Term
|
Definition
| Constant velocity when force of air resistance = force of gravity |
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Term
| Newton's Second law of motion |
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Definition
| Force is directly proportional to the product of the mass and the acceleration. Force is directly proportional to the rate of change of momentum |
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Term
| Translational equilibrium |
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Definition
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Term
| Newtons Third law of motion |
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Definition
| For every action there is an equal and opposite reaction. |
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Term
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Definition
| Product of mass and velocity |
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Term
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Definition
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Term
| Law of conservation of linear momentum |
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Definition
| Total momentum is constant in the absence of external forces. |
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Term
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Definition
| Directly proportional to the product of the force and displacement |
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Term
|
Definition
| Directly proportional to the product of the mass and the square of the velocity |
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Term
| Gravitational potential energy |
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Definition
| Directly proportional to the product of the mass and change in height. |
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Term
| Principle of conservation of energy |
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Definition
| Energy cannot be created nor destroyed. Energy can only be transferred. |
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Term
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Definition
| Work per unit mass required to move a point mass from infinity to point P in the gravitational field |
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Term
|
Definition
| Rate of change of energy transferred |
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Term
| Gravitational potential energy |
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Definition
| Work done in moving a point mass from infinity to a point P in the gravitational field |
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Term
| Relationship between equipotential surfaces and gravitational field lines |
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Definition
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Term
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Definition
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Term
|
Definition
| Add 273 to Celsius therefore 274 |
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Term
|
Definition
| The specific latent heat of a substance is the energy required to change the phase of 1 kg of a substance |
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Term
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Definition
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Term
| State the assumptions of the kinetic model of an ideal gas (six) |
|
Definition
1. Spherical
2. Elastic collisions
3. Volume of molecules are very small in comparison to the volume of the gasp
4. No forces of attraction between molecules/ atoms
5. Time of collision much less than time between collisions.
6. Newtons laws apply
7. No gravitational effect
8. Random motion
9. |
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Term
|
Definition
| Average random kinetic energy of the molecules of an ideal gas |
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Term
| Ideal gas versus real gas |
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Definition
| An ideal gas cannot be liquefied |
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Term
| Absolute Zero - ke of particles and entropy = |
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Definition
| Kinetic energy of molecules are zero and no entropy |
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Term
| First law of thermodynamics |
|
Definition
| Energy is neither created nor destroyed it can only be transferred |
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Term
|
Definition
Change in volume = zero
Work done = 0
Change in internal energy = change in energy transfer |
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Term
|
Definition
Change in pressure = 0
change in internal energy = change in energy transfer change in the work done |
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Term
|
Definition
For an ideal gas isothermal = 0 change in internal energy
Change in energy transferred = – change in the work done |
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Term
|
Definition
Change in energy transfer = 0
Change in internal energy = change in the work done |
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Term
| Second law of thermodynamics |
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Definition
| Entropy of the universe will always increase |
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Term
|
Definition
| Degree of disorder in the system |
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Term
|
Definition
| Distance of any point from equilibrium position |
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Term
|
Definition
| Maximum displacement from equilibrium position |
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Term
|
Definition
| Number of cycles per second (hertz) |
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Term
|
Definition
| Time taken to complete one cycle |
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Term
|
Definition
| Fraction of a cycle by which one source moves behind the other |
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Term
|
Definition
| Motion where the acceleration is directly proportional to the displacement but in the opposite direction |
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Term
|
Definition
| Force that is always in the opposite direction to the direction of the motion of the oscillating particle. The force is the dissipative force. |
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Term
| Natural frequency of vibration |
|
Definition
| Frequency at which an object or particle will oscillate at in the absence of external forces |
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Term
|
Definition
| forced to go at a frequency other than its natural frequency of vibration |
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Term
|
Definition
| Natural frequency of oscillation = driving frequency causing the maximum amplitude |
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Term
|
Definition
| THERMAL energy that is lost to the surroundings and is no longer available to perform useful work |
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Term
|
Definition
| Energy released per unit mass |
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Term
| Four possible reasons (models) for global warming |
|
Definition
Greenhouse gases
Solar activity
Volcanic activity
Earth orbit |
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Term
| Evidence that links global warming and increased amount of greenhouse gases |
|
Definition
International ice core research - notably ice cores drilled from
Vostok in 1998 relate temperature change to CO2 |
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Term
|
Definition
| Ratio of the power of radiation reflected to the total power incident on the body. |
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Term
| Factors that determine albedo 3 |
|
Definition
| Time of year, latitude, environment: desert land, forests , water |
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Term
|
Definition
| Warming of the earth caused by infrared radiation emitted by the earth surface, which is absorbed by various gases in the earth's atmosphere. Primary gases responsible are water vapour, carbon dioxide, methane and nitrous oxide |
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Term
|
Definition
| A theoretical body that is a perfect emitter |
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Term
| Increase the temperature of a blackbody will increase... |
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Definition
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Term
|
Definition
| The power (energy per second) is directly proportional to the product of the surface area, absolute temperature tk the fourth power and the properties of the surface. |
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Term
|
Definition
| Energy required to raise the temperature of one unit area of the planets surface by 1° |
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Term
|
Definition
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Term
|
Definition
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Term
|
Definition
|
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Term
| LP's (Long Playing Record) |
|
Definition
Sound is a vibration of particles across a medium.
The vibration of sound vibrates the needle. The needle makes grooves in the record.
Upon playback the needle retraces the grooves.
Vibrations are amplified and then fed-into a reader. |
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Term
|
Definition
| Sequence imprinted onto a CD. Covered in a continuous spiral of PITS and lands. LASER light is used - MONOCHROMATIC. Light hits a pit or land directly then all the light reflects back and there is no change. Where between the edge of the pit and land the light had to travel y/2 more as the depth of the pit is (Y/4)! Therefore out of phase and causes DESTRUCTIVE INTERFERENCE(1) |
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Term
|
Definition
| Retrieval speed, reproducibility, portability, manipulation of data |
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Term
| Implications for society of increasing capability of data storage. |
|
Definition
| Data can be retrieved by criminals easily - data has the potential to harm in the wrong hands. |
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Term
|
Definition
| The charge per-unit potential difference that can accumulate on a conductor. |
|
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Term
|
Definition
Charged coupled devices. Stores and displays images. Silicon chip (semiconductor) divided into millions of small areas known as pixels. Each pixel behaves as a capacitor. When light is incident on a pixel an electron is released. The number of electrons released depends upon the intensity of light. More intense light releases more electrons and thus has a greater negative charge.
Each pixel has a coordinate which is read out and digitalised by discharging each pixel. |
|
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Term
|
Definition
| The charge is transferred across the CCD a row at a time. Before the next row arrives, the charge is moved to the readout pixel one pixel at a time. The charge is converted to a potential difference which is then stored in binary form. A potential difference is applied to move the next row down. |
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Term
|
Definition
| Ratio of the number of photo electrons emitted to the number of photons incident on the pixel |
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Term
|
Definition
| The ratio of the length of the image on the CCD to the length of the object |
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Term
|
Definition
| Images of the points are at least two pixels apart |
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Term
|
Definition
image capturing in a large range of the electromagnetic spectrum.
Also good in low intensity light |
|
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Term
|
Definition
| Electrodes measure the pd developed across each pixel. This is then converted into a digital signal. Pixel position is also stored |
|
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Term
|
Definition
Product of the normal component of the magnetic field strength and the area that it links.
=BAcos(•) |
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|
Term
| Evidence for nuclear model of the atom |
|
Definition
| Geiger – Mardsen experiment |
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|
Term
| Limitation of the simple model of the nuclear atom |
|
Definition
| Electrons travelling in orbits which are therefore accelerating should emit EM radiation as accelerating charges emit electromagnetic radiation. This would lead to a loss of energy, resulting in their electrons spiralling in words, towards the nucleus. |
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Term
|
Definition
| Nuclei with differing number of protons |
|
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Term
|
Definition
Positive protons repel (coulomb interaction).
Strong nuclear force is an attractive force between nucleons (short range nuclear interaction). |
|
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Term
|
Definition
Proton electron = neutron
BUT NO ELECTRON IN
NUCLEUS SO...
Proton = neutron (opposite electron)
Proton = neutron positron neutrino |
|
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Term
|
Definition
| Neutron = proton electron antineutrino |
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|
Term
| Biological effects of ionising radiation |
|
Definition
High dose: death, loss of coordination
Med: damages stomach |
|
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Term
|
Definition
| Dependent on the ratio of neutrons to protons |
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Term
|
Definition
| Random and spontaneous. Rate of decay decreases exponentially time |
|
|
Term
|
Definition
| Time taken for undecayed nuclei to halve |
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|
Term
|
Definition
| Probability that the nucleus will decay at any second |
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|
Term
| Explain what artificial (induced) transmutation is and give an example. |
|
Definition
Atoms of one element are transferred into atoms of other elements by inducing nuclear reactions.
By Bombing target material with high-energy particles
Eg in a tokamak - hydrogen converted to plasma |
|
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Term
|
Definition
| Equal to 1/12 of the mass of an atom of carbon 12 |
|
|
Term
|
Definition
| Difference between mass of nucleus and total mass of nucleons |
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Term
|
Definition
| Energy required to separate nucleons in a nucleus or the energy released when nucleons come together to form the nucleus |
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Term
|
Definition
| One large nuclei split into two smaller nuclei. Required high-temperature, high-pressure, control rods |
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|
Term
| Nuclear fusion definition and conditions |
|
Definition
| Two small nuclei join to form one big nuclei. High-temperature, high-pressure and magnetic fields. |
|
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Term
|
Definition
| Electromagnetic radiation is incident on a metal surface. If the light is of a sufficient frequency, a photon is absorbed which in turn releases a valence electron. 1 absorbed photon = 1 electron. Showed light is particle like. |
|
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Term
|
Definition
Piece of metal and collecting plate placed in a vacuum (atoms do not interfere with photon electron path) - with a gap between the two. Collecting plate is connected to the negative negative terminal of the battery. Light of a specific wavelength is shone onto metal. Only electrons with sufficient kinetic energy can collect on the plate. Apply a stopping potential on the negative terminal - high pd jar causes the current to fall as the electrons do not have sufficent energy to overcome the pd. the last electrons to leave have the max kinetic energy. Therefore the voltmeter reads the
Max ke of the electrons. Plot max ke against photon freq |
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|
Term
| Photoelectric effect dispelled wave theory |
|
Definition
1. No time delay
2. Increasing intensity does not have impact - only increasing frequency.
3. |
|
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Term
|
Definition
| All matter and radiation have a wave particle duality |
|
|
Term
| Davison – Germer experiment |
|
Definition
Test the duality of matter.
To everyone electrons were always the fundamental particles.
Shooting electrons at crystal surface which resulted in diffraction patterns |
|
|
Term
| Outline laboratory procedure for producing and observing atomic spectra |
|
Definition
| Emission in a prism. Absorption in spectrometer. |
|
|
Term
| Electron in the box model |
|
Definition
| The model assumes that, if an electron confined to move in a one dimension by a box, the De Broglie waves associated with the electron will be standing waves. Wavelength = 2L/N |
|
|
Term
| Schrodinger model of hydrogen atom |
|
Definition
Assumes electrons and atoms can be described by wave functions. Only certain wavelengths that lead to standing waves are allowed. Electrons = undefined position.
Amplitude of wave function SQUARED = probability of finding electron |
|
|
Term
| Heisenberg uncertainty principle |
|
Definition
Cannot know the position and momentum
Or time and energy |
|
|
Term
| Estimating radii of nuclei |
|
Definition
|
|
Term
| Brain bridge mass spectrometer |
|
Definition
|
|
Term
| Evidence for existence of nuclear energy levels |
|
Definition
| Alpha particles have discrete energies as do gamma ray Spectra. |
|
|
Term
|
Definition
| Continuous therefore neutrinos were postulated to account for the spectra |
|
|
Term
| Measuring long half lives |
|
Definition
| Mass has to be determined at t=0. After some time t, the undecayed nuclei are separated and the mass determined. Using M=moe-yt. From this the half life is calculated. |
|
|
Term
| How to measure short-term half life? |
|
Definition
| Number of decays that occur in a specific time interval are unmeasured and graphed against time |
|
|
Term
| Smaller wavelength on CD = advantages (4) |
|
Definition
More layers on Bly ray dial.
Wavelength smaller therefore higher resolution
Track separation can be smaller
Pit spacing can be smaller
More information stored |
|
|
Term
Diagram of Geiger
Mardsen. |
|
Definition
1. Radon lead box.
2. Thin gold foil
3. Vacuum
4. Detector |
|
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Term
|
Definition
| Returns to equilibrium without performing oscillations |
|
|
Term
|
Definition
Same as critical damping (ie no oscillation)
Takes much longer to stop |
|
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Term
|
Definition
| Disturbance that travels parallel the direction of energy transfer. Transfer of energy by means of vibrations. |
|
|
Term
|
Definition
| Disturbance that moves perpendicular to the direction of energy transfer |
|
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Term
|
Definition
| Point of maximum amplitude |
|
|
Term
|
Definition
| Point of the minimum amplitude |
|
|
Term
|
Definition
| Higher than normal density |
|
|
Term
|
Definition
| Lower than normal density |
|
|
Term
|
Definition
| Energy transferred by wave over the product of the area and time |
|
|
Term
| Intensity is proportional to… |
|
Definition
|
|
Term
| Where resonance is useful |
|
Definition
| Microwave generators, quartz oscillators |
|
|
Term
| Examples where resonance is dangerous |
|
Definition
|
|
Term
|
Definition
|
|
Term
| Can transverse waves propagate through gases? |
|
Definition
| Not in the way gases do. It prefers a vacuum |
|
|
Term
|
Definition
| Rays are perpendicular to wavefronts |
|
|
Term
| Electromagnetic wave speed in free space and orders of mag of wavelengths. |
|
Definition
Travel at same speed (3*10^8)
Look at pix |
|
|
Term
|
Definition
| Angle of incidence = angle of reflection. |
|
|
Term
|
Definition
| Ratio of the sin(incidence angle) to the sin(refracted angle) equals the ratio of the velocity in medium 1 to the Velocity in the second medium. |
|
|
Term
|
Definition
| Speed of light in a vacuum (c=3*10...) / speed of light in that medium |
|
|
Term
| Principle of superposition |
|
Definition
| When two waves pass through the same region of space at the same time the resultant displacement is the sum of their separate displacements. |
|
|
Term
| Nature of standing waves (3things) |
|
Definition
No net energy transfer
Every point on the wave has a different amplitude.
In phase between two nodes. |
|
|
Term
| How do you form a standing wave |
|
Definition
| Two waves of the same amplitude and frequency travelling in opposite direction must pass through each other. |
|
|
Term
| Modes of vibration (open) |
|
Definition
| First/ fundamental harmonic: 1 node |
|
|
Term
| Modes of vibration (closed) |
|
Definition
|
|
Term
| What is meant by the Doppler Effect |
|
Definition
Apparent change in frequency when 1. A wave source is moving and there is an apparent change in wavelength of wave.
2. An observer is moving resulting in an apparent change in wave speed. |
|
|
Term
| Describe doppler effect for when source is moving |
|
Definition
| A source moving at constant speed towards an observer emits a constant frequency. As the source moves towards the observer there is an apparent change in wavelength according to the observer. Increasing the frequency. VISA VERSA FOT SOURCE MOVING AWAY FROM OBSERVER FREQUENCY DECREASES. |
|
|
Term
| Describe doppler effect when observer is moving toward source |
|
Definition
| Stationary source emitting at a constant frequency. Observer moves towards the source at a constant velocity. Observer can claim he is at rest and source is approaching him at speed = speed of wave speed of obsever. This results in an apparent change in wavespeed. |
|
|
Term
| When the Doppler effect applies to light... |
|
Definition
| As speed of light is soooooo large compared to speed of observer or source the equation is simplified to this approximation. |
|
|
Term
|
Definition
| Measuring vehicle speeds. Measurement of blood flow. |
|
|
Term
|
Definition
| Light only oscillates in one plane |
|
|
Term
| Polarisation by reflection |
|
Definition
| When unpolarised light reflects off a non metallic surface- the reflected ray is partially polarised. Plane of polarisation is perpendicular to the reflecting surface THEREFORE resultant light is parallel to the reflecting surface |
|
|
Term
|
Definition
In order for objects to be resolved angular separation must be greater than 1.22y/b. minimum. The light used to resolve the object must be the same size or
smaller than the object. |
|
|
Term
|
Definition
| The angle of incidence that causes the reflected ray to be 100% polarised and therefore the angle at which the angle between the reflected and refracted ray is 90 |
|
|
Term
|
Definition
| Polariser reduces light intensity by 50% to produce polarised light where light only oscillates in one plane. |
|
|
Term
|
Definition
| determines if light is polarised. |
|
|
Term
| Optically active substance |
|
Definition
| Rotates the plane of polarisation |
|
|
Term
| Relationship between the concentration of a solution and polarisation of light |
|
Definition
| Increasing the concentration of solution increases the angle by which the plane of polarisation is rotated. |
|
|
Term
| How may polarisation be used in stress analysis? |
|
Definition
| Materials not normally optically active become so under stress. The degree of optical activation is proportional to the stress. |
|
|
Term
|
Definition
Surface of pixels. Each pixel has liquid crystals between two glass plates. Thin slits on first glass plate so molecules align. Second glass plate same slits but perpendicular to slits in glass 1.
When voltage applied molecules align with electric field and pixel will be dark. No pd then bright. |
|
|
Term
| Electric potential difference |
|
Definition
| Work done per unit charge to move a small positive test charge between two points. |
|
|
Term
|
Definition
| Work done when a charge equal to one electron charge is taken across a potential difference of one volt. |
|
|
Term
|
Definition
Rate of flow of charge.
Force per unit length between parallel current - carrying conductors. |
|
|
Term
|
Definition
| Ratio of potential difference to current |
|
|
Term
|
Definition
| States that the voltage is directly proportional to the current |
|
|
Term
|
Definition
| Total work done in moving a unit charge completely around the circuit. |
|
|
Term
|
Definition
| Material of a cell causes resistance. Not perfect conductor. As the atoms vibrate energy loss in form of heat. Converted from electrical to heat |
|
|
Term
|
Definition
| Measures current therefore no resistance |
|
|
Term
|
Definition
| Voltmeter measures voltage therefore in order to measure you need all the volts therefore to use all volts therefore very high resistance |
|
|
Term
| Potential divider. Giving ratio of v(out) to v(in) |
|
Definition
Used to switch on and off secondary circuits as environmental conditions change.
Two non ohmic resistors connected in series.
Current through each resistor is equal. Secondary circuit is connected before and after the first resistor. Second resistor acts as a variable resistor. R1/R1 R2 |
|
|
Term
| Potential divider r2 decreases then... |
|
Definition
|
|
Term
| Resistance increases on r2 in potential divider. |
|
Definition
|
|
Term
LDR's
Increase in light = ... In resistance |
|
Definition
|
|
Term
Thermistor
Increase in temp = ... in resistance |
|
Definition
|
|
Term
|
Definition
P=W/T
W=VQ
P=VQ/T
Q/T=I
Therefore
P=IV |
|
|
Term
| Neutrons in nuclear reactors |
|
Definition
Sustain nuclear reactions.
Chain reaction.
U235 can only capture slow neutrons. |
|
|
Term
|
Definition
| In order for reaction to occur need a certain minimum mass of uranium 235 otherwise neutrons escape without causing further reactions. |
|
|
Term
| Controlled nuclear production v uncontrolled. |
|
Definition
Controlled Nuclear fission = power production
Uncontrolled nuclear fission = nuclear weapons |
|
|
Term
|
Definition
| Increases the percentage of u235 to 3% or more |
|
|
Term
| Main energy transformations in nuclear |
|
Definition
| Nuclear - kinetic - thermal - kinetic - electrical |
|
|
Term
|
Definition
Material surrounding fuel rods
Reduces speed of neutrons by colliding with neutrons. so that chance of initiating fission is higher.
Material = graphite/ water |
|
|
Term
|
Definition
| Absorb excess neutrons( too many can lead to excess energy released). Can be removed and reinserted upon need. |
|
|
Term
| Role of heat exchanger (nuclear) |
|
Definition
Heat exchanger turns water to steam at high temp and pressure.
Steam used to turn turbines |
|
|
Term
| Describe how some reactors are used to produce plutonium |
|
Definition
Uranium 238 (92) absorbs neutron = uranium 239 (92)
(Beta - decay)*2
To give Pu(239-94)
SHOET VERSION:
U238 present - most abundant
U238 absorbs fast proton to produce plutonium |
|
|
Term
| Why is uranium to plutonium important ? |
|
Definition
| 1. U238 = non fissionable |
|
|
Term
|
Definition
| Products = highly reactive, long half lives |
|
|
Term
| Problems associated with nuclear fusion |
|
Definition
| Maintaining and controlling a high temp and high density plasma environment. |
|
|
Term
| Outline what happens in nuclear fusion |
|
Definition
| Deuterium and tritium = helium |
|
|
Term
|
Definition
| Energy transferred to or from the system |
|
|
Term
|
Definition
|
|
Term
|
Definition
| Calculates intensity of polarised light given angle of polariser and maximum intensity |
|
|
Term
|
Definition
States that the force exerted on a spring is directly proportion to the displacement.
F = -kx |
|
|
Term
|
Definition
2pi/w
W= angular frequency of motion |
|
|
Term
| Is the period of an oscillation affected by its amplitude? |
|
Definition
No. T = 2pi/2
T= root (length of string/ g) * 2pi |
|
|
Term
|
Definition
Voltage is potential difference therefore in order to calculate must be between two points. PD is not same across circuit.
In series v total= I(r1 r2 etc). |
|
|
Term
|
Definition
Same across whole of circuit - rate does not change.
I= Vtotal/ R total |
|
|
Term
|
Definition
| Voltage is same across whole of circuit. Do not add voltage etc |
|
|
Term
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Definition
Current = total current in parallel =
Current in series. |
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Term
| Describe inducing of an emf by relative motion between a conductor and a magnetic field. |
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Definition
Picture mag field going into page.
Wire is moved down horizontally along page.
Therefore force is to right and electrons are pushed to right - electrons moving to right = current moving to left.
Current is induced therefore emf is induced |
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Term
| Derive formula for emf induced in a straight conductor moving in a magnetic field. |
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Definition
Emf=work done per unit charge
W= f*l
F=qvb
W= qvbl
E= qvbl/q
=blv |
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Term
| Magnetic flux: intuitive and IB def |
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Definition
Intuitive: no of field lines ( which do not exist) passing through an area
IBdef: product of normal component of magnetic field strength and area of loop |
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Term
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Definition
| product of normal component of magnetic field strength, area of loop and number of turns of wire in loop |
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Term
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Definition
| = induced emf is equal to the negative rate of change of magnetic flux. |
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Term
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Definition
| Induced emf will be in direction that opposes change in magnetic flux that created the current |
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Term
| Emf induced in a coil rotating within a uniform magnetic field is... If rotation is at constan speed |
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Definition
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Term
| What is meant by root mean squared value of an alternating current or voltage? |
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Definition
| The value of the direct current or voltage that dissipates power in a resistor at the same rate. |
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Term
| The rms value is also known as the... |
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Definition
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Term
| Possible risks of living and working near power lines. |
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Definition
Current evidence suggest low freq radiation does not harm genetic material.
Not fully understood.
Risks are dependent upon current, frequency and length of exposure. |
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Term
| Efficiency of modern natural gas power station |
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Definition
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Term
| What increases the current registered by galvanometer connected to loop of wire exposed to changing magnetic flux. |
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Definition
- increase speed of magnet
- increase number of turns of wire
- increase area of loop of wire
- magnet moves perpendicular to plane of loop |
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Term
| How do you determine direction of magnetic field in solenoid? |
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Definition
| Use right hand thumb rule. Direction of magnetic field is the same as the direction of the current. |
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Term
| In order for two variables to be proportional |
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Definition
Must be -linear
- go through 0,0 |
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Term
| Doubling the frequency of ac generator does what... |
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Definition
| Doubles peak voltage and doubles frequency of current/voltage |
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Term
| Thermal energy may be completely converted to work in a single process BUT |
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Definition
| Continuous conversion is a cyclic process - some energy will be transferred to surroundings. |
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Term
| Photovoltaic cell - describe energy transfers and uses of device |
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Definition
Converts sunlight to electricity.
Use semiconductors
Valence electrons - charge - current created
Used in calculators, now solar power |
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Term
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Definition
| Sunlight used to heat water or air for use in house . |
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Term
| Percentage of energy sources: coal |
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Definition
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Term
| Percentage of energy sources: gas |
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Definition
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Term
| Percentage of energy sources: nuclear |
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Definition
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Term
| Percentage of energy sources: hydro |
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Definition
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Term
| Percentage of energy sources: oil |
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Definition
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Term
| Efficiency of oil power station |
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Definition
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Term
| Efficiency of gas power station |
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Definition
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Term
| Outline historical and geographical reasons for the widespread use of fossil fuels. |
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Definition
Industrialisation = higher rate of energy use
As coal has a much higher energy density than coal.
Started to use coal - widespread use was there because hard to mine.
Built industry near fossil fuels - minimise cost of transportation . |
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Term
| Adv and disadvantage of transportation and storage of fossil fuels. |
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Definition
Disadvantages: expensive to transports as large masses, need
Extensive storage facilities as high volume. Oil leaks
Advantages: coal is inert - will not react. |
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Term
| Environmental problems associated with recovery of fossil fuels. |
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Definition
Produces large no of toxic substances. High in sulphur content - ( acid deposition).
Traces of heavy metals = eutrophication. |
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Term
| Neutrons used in nuclear fission are of what energy |
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Definition
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Term
| Reasons for seasonal and regional variations in the solar power per unit area of earth's surface. |
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Definition
Earth not constant distance from earth and power output not constant.
Due to latitudes - higher latitudes energy is spread over a greater area. |
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Term
| Name different hydroelectric schemes and outline how they work. |
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Definition
Water storage in lakes - as high elevation as possible to maximise pe.
Pump storage system: water that flows to lower heights is pumped back by generators of plant.
Tidal storage: flow of water during a tide turn turbines - producing electricity. |
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Term
| Main energy transformations in hep |
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Definition
| Potential to kinetic to electrical |
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Term
Basic features of a
Wind generator and main energy transformations |
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Definition
Wind turns blades.
Turns turbine = electrical energy.
Solar - kinetic - kinetic rotation - electrical |
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Term
| Determine power that may be delivered by a wind generator assuming that the wind kinetic energy is completely converted into mechanical energy. Is this possible and why? |
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Definition
Use power and ke formula.
Input mass of wind - rem cylinder shape. |
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Term
| Describe principle of operation of an oscillating water column. |
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Definition
As wave approaches air rises and pushes air - air passes through turbine and turns it.
As trough of wave falls draws air from atmosphere - turns turbine as air moves back down to fill vacuum. |
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Term
| When determining power per unit length of wavefront what equation and under what assumptions. |
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Definition
power per unit length = (A*2pgv)/2
rectangular wave profile |
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Term
| Idea behind energy balance |
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Definition
| Earth is like a black body as constant average temperature so energy in must equal energy out. |
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Term
Write energy balance equation
And understand it |
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Definition
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Term
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Definition
| Ratio of power emitted by a black body to power emitted if it were a black body. |
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Term
| Relationship between gravitational field strength and gravitational potential |
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Definition
Field strength =
Negative gradient of potential |
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Term
| Significance of resolution in development of CD/DVDs |
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Definition
Increased resolution = smaller wavelength needed as angular separation needed gets smaller.
Smaller wavelength = smaller pot depth = fit more |
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Term
| Significance of resolution in radio telescopes. |
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Definition
| Since wavelength of radio telescopes is very large to get good resolution need large slit width = large aperture. Need large dish like receivers. |
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Term
| Significance of resolution in electron microscope |
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Definition
| Wavelength of light must be very small or same order of magnitude as object. |
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Term
| Power dissipated in conductor |
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Definition
=IV
used to perform work or lost as thermal energy |
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Term
| When calculating activity / half life etc. time is in.... |
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Definition
| just use same units of time all the way through. Therefore all seconds or all minutes etc |
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Term
| Explain how greenhouse gas causes global warming? |
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Definition
1. GG will absorb infrared radiation because infrared frequency is = natural frequency of oscillation therefore resonance occurs.
2. Re radiate energy in RANDOM directions which prevents energy escaping into space. |
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Term
| Magnitude of mass of earth |
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Definition
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Term
| Relationship between emf induced and magnetic flux: |
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Definition
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Term
| Why does a photon have momentum |
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Definition
P = h/wavelength.
They have momentum
No rest mass but have momentum |
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Term
| Energy transformations in oscillating water and column |
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Definition
Initial = kinetic
Then potential = vacuum
Then kinetic. |
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Term
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Definition
| Must mention electrical generator |
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Term
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Definition
Small area on a
Semiconductor chip. Smallest part of the chip that can detect a photon. |
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Term
How does light incident on CCD
Cause electric signal |
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Definition
Photons = emission of electron
= Change in potential difference
Potential difference correspond to light intensity. |
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Term
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Definition
| Greater quantum efficiency. Sensitive to wider range of em spectrum. Processing time of image = shorter. |
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Term
| State why only average kinetic energy of molecules of an ideal gas is related to the internal energy of the gas. |
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Definition
Potential energy not used.
No forces between molecules in an ideal gas.
Gas speeds vary so need to take an average. |
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Term
| Pv diagrams constant temp = what type of line and q = 0 what line |
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Definition
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Term
| Stanley diagram how do you calculate efficiency |
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Definition
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Term
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Definition
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Term
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Definition
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Definition
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| Magnitude of magnitude of electric field between two plates. |
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Definition
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Term
| Increasing distance between slit and screen - increases / decreases distance between central maxi and first minimum |
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Definition
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Term
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Definition
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Term
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Definition
| Work done per unit charge supplied by the supply |
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Term
| Travelling / progressive wave |
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Definition
| A wave that transfers energy between two points in medium. |
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Term
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Definition
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Term
| Two wires same direction of current will...why? |
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Definition
Attract.
Current in one wire produces mag field in region of adjacent turn.
Thus gives force - and attraction occurs. |
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