Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
148 Cards in this Set
- Front
- Back
Displacement |
The distance from a fixed point along a particular direction |
|
Velocity |
The rate of change of displacement (m/s) |
|
Acceleration |
The rate of change of velocity (m/s2) |
|
Scalar quantity |
A quantity that has no direction eg mass |
|
Vector quantity |
A quantity that has direction and magnitude associated with it (eg velocity) |
|
Force |
Something that can cause acceleration (N) |
|
Friction |
A force that opposes the movement of one surface over another |
|
Momentum |
Mass × velocity (kgm/s) |
|
Conservation of momentum |
In any interaction with no external forces the total momentum before is equal to the total momentum after |
|
Newton's first Law of motion |
An object remains in a state of rest or in uniform motion in a straight line unless an external force acts on it |
|
Newton's second law of motion |
The resultant force on an object is proportional to its rate of change of momentum |
|
Newton's third law of motion |
If A exerts a force on B then B exerts an equal and opposite force on A |
|
Weight |
The weight of a body is the force of gravity acting on it |
|
Newton's universal law of gravitation |
|
|
Density |
The mass per unit area (kg/m3) |
|
Pressure |
The force per unit area (Pa) |
|
Archimedes' Principle |
When a body is partially or wholly immersed in a fluid the upthrust is equal in magnitude to the weight of the fluid displaced |
|
Law of floatation |
The weight of floating body is equal to the weight of fluid displaced |
|
Moment |
Perpendicular distance × force |
|
Couple |
A system of forces which have a turning effect only and the resultant is zero |
|
Equilibrium |
When a body's acceleration is zero |
|
Law of Equilibrium 1 |
The sum of the forces acting on the body is zero |
|
Law of Equilibrium 2 |
The net total clockwise moment equals the net total clockwise moment |
|
Energy |
The ability to do work |
|
Principle of Conservation of energy |
Energy can neither be created nor destroyed merely converted from one form to another |
|
Work |
Force × distance moved |
|
Power |
Work done per second |
|
Watt |
One joule per second |
|
Efficiency |
Power in÷power out |
|
Heat |
The measure of energy (Joules) |
|
Temperature |
A measure of the hotness of a body (Kelvin) |
|
Specific Heat Capacity |
The amount of energy needed to change the temperature of 1kg of that substance by 1 Kelvin |
|
Specific Latent Heat |
The heat energy needed to change the state of 1kg of a substance with no change in temperature |
|
Thermometric property |
A physical property that changes measurably with changing temperature |
|
Conduction |
The transfer of energy through a substance without the movement of the particles of the substance |
|
Convection |
The transfer of energy through a substance by the movement of the particles |
|
Radiation |
The movement of energy in straight lines from the surface of a hot body without the need for a medium to pass through |
|
Solar constant |
Amount of solar energy per second per 1m2 of area (Watts per m2) |
|
U-value |
The u-value of a building material is the amount of heat energy that will escape per second through 1m2 of the material for each 1K temperature difference across it |
|
Celsius |
Kelvin temperature - 273.15 |
|
Boyle's Law |
When a fixed mass of gas is kept at a constant temperature its pressure is inversely proportional to its volume |
|
Stationary wave |
A wave with no net transfer of energy formed by interference of two waves of equal frequencies and amplitudes moving in opposite directions |
|
Harmonics |
Frequencies which are whole number multiples of a fundamental frequency |
|
Resonance |
Transfer of energy between bodies with similar natural frequency |
|
Sound intensity |
Sound energy per second crossing each square metre of area (Watts per m2) |
|
Threshold of hearing |
The smallest intensity that can be heard by a human ear (1x10-12 W per m2) |
|
Threshold of pain |
Intensities above 1W/m2 cause pain and permanent damage |
|
Sound intensity level |
The change in sound intensity level is 1 Bel when the second sound intestinal is 10 times the first |
|
dB(A) scale |
dB except has been adapted to take into account of how the human ear responds differently to different frequencies |
|
The Doppler Effect |
The apparent change in frequency of a wave due to the relative motion between the source of the wave and the observer |
|
The first Law of reflection |
The angle of incidence is equal to the angle of refraction |
|
The second law of reflection |
The incident ray, the normal and the reflected ray are all in the same plane |
|
The first Law of refraction |
Sin i/sin r = the refractive index a constant |
|
The second law of refraction |
The incident ray the normal and the refracted ray all lie in the same plane |
|
Power of a lens |
1/focal length in m |
|
Critical angle |
The angle of incidence in the denser medium for which the angle of refraction will be 90° |
|
Total internal reflection |
Occurs when the angle of incidence in the denser medium is bigger than the critical angle |
|
Transverse wave |
The vibrations are at right angles to the direction the particle travels in |
|
Longitudinal waves |
The vibrations are parallal to the direction in which the wave travels |
|
Wavelength |
The distance between two crests (m) |
|
Amplitude |
The max displacement from the baseline (m) |
|
Frequency |
The number of complete cycles of a wave passing a point per second (Hz) |
|
Period |
The time taken for a complete cycle of a wave (s) |
|
Wavequation |
C=¥f |
|
Reflection |
The rebounding of a wave/light off a surface |
|
Refraction |
The bending of a wave as it passes from one medium to next (n=c1/c2) |
|
Diffraction |
The spreading out of a wave in the space behind an obstacle or after going through an opening N¥=dsin0 |
|
Interference |
When two or more waves meet and combine to form a resultant wave |
|
Coherent sources |
Sources that are in phase and have the same frequency |
|
Polarisation |
This is when the vibrations of a wave are in one plane only: only happens with transverse waves |
|
Dispersion |
The separation out of white light into its constituent colours |
|
Primary colours |
Red green blue-produce white light |
|
Secondary colours |
Yellow cyan magenta-when primary colours are mixed in equal intensity |
|
Complementary colours |
A primary and secondary colour mixing to give white light |
|
Conductor |
A substance that allows charge to flow through it |
|
Insulator |
A substance that does not allow charge to flow through it |
|
Electric field |
A region where a charged particle experiences a force |
|
Electric field strength |
The force per unit charge (E=F/q) |
|
Potential difference |
Work done per unit charge (V=W/q) |
|
Emf |
The work done in bringing unit charge around a complete circuit (V) |
|
Capacitance |
The ratio of charge to potential difference (C=Q/V) |
|
Coulomb's law |
|
|
Electric current |
A flow of charge (A= 1 Coulomb per second) |
|
Resistance |
The ratio of voltage to current R=V/I |
|
Resistivity |
|
|
Ohm's Law |
The current flowing through a wire is proportional to the potential difference across it V=IR |
|
RCD |
Residual Current Device |
|
MCB |
Miniature Circuit Breaker |
|
Semiconductor |
Resistivity between that of a conductor and an insulator |
|
Intrinsic vs Extrinsic conduction |
Conduction in a pure vs doped semiconductor |
|
Thermionic emission |
Emission of electrons from the surface of hot metal |
|
Electron-Volt |
The amount of energy gained by an electron being accelerated across a potential difference of 1 Volt |
|
Photoelectric emission |
The emission of electrons from the surface of a metal when light of a suitable frequency falls on it |
|
Photon |
A packet of electromagnetic energy (energy=hf) |
|
Work function |
The minimum energy required by a photon to remove an electron from the surface of a metal by photoelectric emission (J or eV) |
|
Threshold frequency |
The minimum frequency required for photoemission to occur |
|
Einsteins photoelectric law |
Photon energy=work function +max kinetic energy of emitted electron |
|
X rays |
High frequency photons of electromagnetic radiation |
|
Atomic number |
Number of protons in the nucleus of an atom of that element |
|
Isotopes |
Atoms that have the same atomic number but different mass numbers |
|
Radioactivity |
The decay of a nucleus of an atom with the emission of one or more types of radiation |
|
Activity |
The number of nuclei of a radioactive substance that is decaying per second |
|
Bequerel |
The unit of activity = one radioactive disintegration per second |
|
Law of radioactive decay |
The number of disintegrations per second is directly proportional to the number of nuclei present |
|
Half life |
The time taken for half of the nuclei present to decay |
|
Decay constant |
|
|
Nuclear fission |
The splitting of a large nucleus into two smaller nuclei with the emission of neutrons and large amounts of energy |
|
Chain reaction |
A self sustaining reaction where the release of one or more neutrons causes further fission |
|
Nuclear fusiin |
The joining together of two light nuclei to form a larger nucleus with the emission of a large amount of energy |
|
Leptons |
A point particle that does not experience the strong force |
|
Hadron |
A particle made of three quarks= proton neutron |
|
Meson |
A particle made of a quark and an anti quark (eg pion) |
|
Anti-matter |
A particle with the same mass as a particle but opposite charge |
|
Pair production |
A particle and it's anti particle are created from high energy (gamma-ray) photon (hf=2mc2) |
|
Pair annihilation |
A particle and an anti particle are converted into two equal photons of energy (travelling in opposite directions) (2hf=2mc2) |
|
Four forces in order of decreasing strength |
Strong nuclear force Electromagnetic Weak nuclear Gravitational |
|
Thermistor |
A semiconductor whose resistance decreases rapidly with an increase in temperature |
|
Holes |
When an electron breaks free from a covalent bond it leaves behind a gap in the atom from whence it came. |
|
Intrinsic Conductor |
Conduction in a pure semiconductor with an equal number of holes moving from positive to negative and electrons moving in the opposite |
|
Parallax |
The apparent movement of an object relative to another due to the motion of an observer |
|
Magnification |
M=v/u |
|
Short sighted |
A short sighted cannot bring far away objects into an object fixed with concave lens |
|
Long sight |
Can't see up close objects fixed with convex lenses |
|
Interference |
When waves combine to create a resultant wave |
|
Pressure in a fluid |
P=pgh |
|
Cathode Rays |
Streams of high speed electrons moving from the cathode |
|
Kilowatt-Hour |
The amount of energy used by a 1000W appliance in one hour |
|
LDR |
Light Dependent Resistor is a semiconductor whose conductivity is increased when light shines on it |
|
Doping |
The adding of a small controlled amounts of certain impurities to a pure semiconductor to increase its conductivity |
|
N-type semiconductor |
One which the impurity added produces more free electrons available for conduction (eg phosphorus) |
|
P type semiconductor |
A semiconductor in which the impurity added produces extra hokes which are available for conduction (eg boron) |
|
Intrinsic conduction |
Conduction in a pure semiconductor due to electrons move from negative to positive and an equal number of holes move in an opposite direction |
|
Extrinsic conduction |
Increased conduction in a semiconductor due to the addition of impurities is called extrinsic conduction |
|
Junction voltage |
The P. D. that exists across a p-n junction caused by holes and electrons moving across the junction when it was formed is called the junction voltage |
|
Forward biased p-n junction |
Conducts current when positive terminal is connected to the P type |
|
Reverse biased p-n junction |
Doesn't conduct current |
|
Magnetic Field |
A region of space where magnetic forces can be felt in the direction of the force on the north pole if it were placed at that point |
|
Magnetic Field Line |
A line drawn in a magnetic field so that the tangent to it at any point |
|
Magentic Flux Density |
A vector whose magnitude is equal to the force that would be experienced by a conductor of length 1m carrying a current of 1 A at right angles to the field |
|
The Ampere |
The current which, if maintained in two straight parallel conductors of infinite length, of negligible cross section and placed 1m apart in a vacuum would produce a force of 2x10(-7) N per metre length |
|
Electromagnetic Induction |
Whenever the magnetic passing through a coil changes, an emf appears in the coil |
|
Emf |
Electromotive Force |
|
Faraday's Law |
The size of the induced emf is directly proportional to the rate of change of flux |
|
Lenz's Law |
The direction of an induced current is always such as to oppose the change producing it |
|
Electric Generator |
A device that converts mechanical energy to electrical energy |
|
Mutual Induction |
When a changing magnetic field in one coil causes an induced emf to appear in a nearby coil |
|
Self induction |
Whenever the current passing through a coil changes, the magnetic field surrounding that coil changes. This changing magnetic field induces an emf in the coil that opposes the changing current (back emf) |
|
Transformer |
A transformer is a device used to change the value of alternating voltage |