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143 Cards in this Set

  • Front
  • Back

State the 2 laws of reflection of light

-The incident ray, normal at the point of incidence and the reflected ray all lie on the same plane


-Angle of incidence = angle of reflection

Define 'parallax'

The apparent movement of one object relative to another due to the motion of the observer

Define 'Virtual Image'

an image formed by the apparent intersection of rays


Define 'magnification'

the ratio of the image height to the object height

State both laws of refraction of light

-the normal, incidence and reflected ray all lie on the same plane



-the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant

Define 'refractive index of a medium'

the ratio of the sine of the angle of incidence to the sine of the angle of refraction when light travels from a vacuum into that medium

Define 'critical angle'

when light travels from a denser to a rarer medium and the angle of incidence whose corresponding angle of refraction on 90 degrees

Define 'total internal reflection'

when light going from a denser to a rarer medium strikes the second medium at an angle of incidence greater than the critical angle so is therefore reflected back into the first media

Define 'speed'

rate of change of distance with respect to time

Define 'displacement'

distance in a given direction

define 'velocity'

rate of change in displacement with respect to time

Define 'acceleration'

rate of change in velocity with respect to time

Define 'scalar quantity'

a quantity which has only magnitude (no direction)

Define 'vector quantity'

a quantity which has both magnitude and direction in space

Define 'vector components'

expressing a vector in terms of 2 other vectors so that it's the resultant of these 2

Define 'perpendicular components'

resolving a vector into components which are right-angles to each other

Define 'force'

anything that causes a body to change (its velocity)

Define 'mass'

a measure of how difficult it is to accelerate that body

Define 'Newton'

1N is the force that gives a mass of 1Kg an acceleration of 1m/s

Define 'weight'

the force of an object due to gravity acting on it

State Newton's 1st law of motion

every body will remain in a state of rest/travel at a constant velocity unless an (unbalanced) external force acts on it

State Newton's 2nd law of motion

when an unbalanced force acts on a body, the rate of change in the body's momentum is directly proportional to the force and takes place in the direction of the force

State Newton's 3rd law of motion

If body A exerts a force on body B, then body B exerts an equal but opposite force on body A

State the principal of conservation of momentum

in the interaction between 2+ bodies, the total momentum of the bodies before and after the interaction is the same (as long as no external force acts on the bodies)

Define 'Density'

mass per unit volume

Define 'pressure'

force per unit area

State 'archimedes' principal'

when an object is partially/fully immersed in a fluid it experiences an upthrust equal in magnitude to the weight of the fluid displaced

State the law of flotation

weight of floating body = weight of fluid it displaces

State Boyle's law

at a constant temperature the volume of a fixed mass of gss is inversely proportional to its pressure

Give the conditions needed for eqilibrium

-vector sum of forces in any direction = 0


-sum of moments about any point = 0

Define 'couple'

two parallel forces with the same magnitude acting in opposite directions

Define 'joule'

1J of work is done when a force of 1N acts for a distance of 1m in the direction of the force

Define 'energy'

the ability to do work

State the principal of conservation of energy

energy can't be created/destroyed, only converted form one form to another

Define 'kinetic energy'

the energy a body has due to its motion

Define 'potential energy'

the energy a body has due to its position ina force field

Define 'power'

-the rate at which work is done



-the rate at which energy is converted from one form to another

Define 'temperature'

the measure of the hotness/coldness of a body

Define 'thermometric property'

any physical property that changes measurably with temperature

Define 'heat capacity of an object'

heat energy needed to change its temperature by 1 K

Define 'specific heat capacity of a body'

heat energy needed to change the temperature of 1Kg of that substance by 1K

Define 'latent heat'

heat energy needed to change a body's state without a change in temperature

Define 'specific latent heat'

heat enery needed to change the state of 1Kg of a substance without a change in temperature

Define 'specific latent heat of fusion'

ammount of heat energy needed to change the state of 1Kg of a substance from solid to liquid without a change in temperature

Define 'specific latent head of vaporisation'

heat of energy needed to change the state of 1Kg of a substance from liquid to gas without a change in temperature

Define 'conduction'

movement of heat energy through a substance by the passing on of molecular vibration without an overall motion of the substance

Define 'U-value of a structure'

heat energy conducted per second through 1m squared of that structure when there's a temperature difference of 1K between its ends

Define 'radiation'

transfer of heat energy from one place to another in the form of electromagnetic waves

Define 'solar constant/irradiance'

average amount of sun's energy falling per second perpendicularly on 1m squared of the earth's atmosphere

Define 'convection'

transfer of heat through a fluid by means of circulating currents of a fluid caused by the heat

define "travelling mechanical wave"

a disturbance carrying energy through a medium without any overall motion of that medium

define "travelling wave"

a disturbance travelling out from its source which transfers energy to other bodies it passes through

define "transverse wave"

a wave where the direction of vibration is perpendicular to the direction the wave is travelling

define "longitudinal wave"

a wave where the direction of vibration is parallel to the direction the wave is travelling

define "amplitude"

the maximum distance of any particle from its undisturbed position (maximum height of vibration)

define "crest"

top of the wave

define "trough"

bottom of the wave

define "oscilltion/cycle of a wave"

the disturbance produced by one complete vibration of the source (1 crest + 1 trough)

define "wavelength"

distance between 2 corresponding points between to cycles of waves

define "frequency"

number of cycles passing any point per second

define "velocity of a wave"

distance travelled by 1 cycle in 1 second

define "wave reflection"

bouncing of waves off of an obstacle in their path

define "wave refraction"

changing of direction of a wave when it enters a region where its speed changes (medium)

define "wave diffraction"

sideways spreading of waves into a region beyond a gap/obstacle


define "wave interference"

when waves from 2 sources meet and a new wave is produced and the amplitude of the new wave is the sum of the amplitudes of the 2 original waves

define "constructive interference"

when waves from 2 sources meet and the resultant amplitude is greater than the amplitudes of the original waves

define "destructive interference"

when waves from 2 sources meet and the resultant amplitude is less than the amplitudes of the original waves

define "coherent sources"

when 2 sources produce waves which are in phase with eachother/which have a constant phase difference between them.


These waves have equal frequency

define "interference pattern"

the wave pattern formed when waves from 2+ coherent sources meet

define "stationary waves"

the resulting wave of when 2 periodic travelling waves of equal frequency+amplitude which move in opposite directions meet + interfere with eachother.

define "doppler effect"

the apparent change in frequency of waves due to the motion of the source/observer

define "overtones"

frequencies that are multiples of a certain frequency (ie f, 2f, 3f etc)


what dictates a sound's "loudness"

amplitude

what dictates a sound's "pitch"

frequency

what dictates a sound's "quality"

number of overtones + relative strengths of the different overtones

define "frequency limits of audibility"

highest and lowest frequency which can be heard by humans

define "natural frequency of vibration"

the frequency at which on object, which is free to vibrate, is most likely to vibrate at


define "resonance"

-when the frequency of a periodic force applied to a body is the same as/near to its natural frequency, that body will vibrate with a large amplitude

define "fundamental frequency"

a string vibrating with an antinode at the center and a node an each end (ie no other nodes/antinodes present)

define "harmonics"

Frequencies which are multiples of an object's fundamental frequency

define "polarisation"

controlling the direction in which an electromagnetic wave is vibrating

define "dispersion"

the separation of the different wavelengths present in light

define "insulator"

a substance an electric charge can't flow through

define "conductor"

a substance an electric charge can flow through

define "electric field"

any region of space where a static charge experiences a force other than gravity

define "potential difference"

-the P.D between 2 points in an electric field is the work done on bringing a charge of 1C from one point to another



-the P.D between 2 points in a circuit is the energy lost by 1C as it moves from A to B

define "the Volt"

the P.D between 2 points is 1 volt if 1 joule of work is done when 1 coulomb is brought from A to B


define "potential at a point"

the P.D between a point and the earth

define "current"

the flow of electrons

what is "electromotive force"

applied P.D in a circuit to maintain an electric field in the circuit

what is "electrolysis"

when a current passes through a liquid/paste and creates a chemical reaction

what is an "electrolyte"

Liquid in which electrolysis occurs in

what is an "electrode"

rods/plates dipped into the electrolyte

what is an "anode"

an electrode connected to the positive terminal of the power supply

what is a "cathode"

an electrode connected to the positive terminal of the power supply

what is a "voltameter"

the container electrodes + electrolytes are in

what are "inactive electrodes"

electrodes which don't take part in the chemical reaction

what are "active electrodes"

electrodes which do take part in the chemical reaction

define "Ion"

an atom/molecule that has lost/gained 1+ electrons

what is the "kilowatt-hour"

amount of energy used by a 1000W appliance in one hour

define "semiconductor"

-a substance whose resistivity is between that of a good conductor and a good insulator


-a substance whose resistance decreases with increasing temperature


what are "valence electrons"

electrons on the outer shell of an atom

what is a "positive hole"

the space remaining when an electron breaks free from a covalent bond

what is a "conduction electron"

an electron which has gained enough thermal energy to break free from a covalent bond

define "intrinsic conduction"

the conduction in a pure semiconductor due to electrons moving from '-' to '+' and an equal number of positive holes moving the opposite direction

define "doping"

the adding of impurities to a semiconductor to increase its conductivity

define "N-type conductor"

a semiconductor in which the impurity added produces more conduction electrons

define "P-type conductor"

a semiconductor in which the impurity added produces more positive holes for conduction

define "extrinsic conduction"

increased conduction in a semiconductor due to the addition of impurities

define "P-N junction"

a semiconductor which is partly doped N-type and the rest doped P-type

define "depletion layer"

the region in a P-N junction in which there are no free majority charge carriers and behaves as an insulator

define "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

define "forward-biased junction"

a circuit in which the diode allows current to flow

define "reverse-biased junction"

a circuit in which the diode doesn't allow current to flow

define "retrification"

converting D.C to A.C

define "magnetic flux density (B)"

B at a point in a magnetic field, is a vector whose magnitude is the force (F) that would be experienced by a conductor of length (L) 1m carrying 1A at right-angles to the field at that point and whose direction is the direction of the force on a north pole placed at that point


define the "ampere"

it's a constant current which, if maintained in 2 straight parallel conductors of infinite length of negligible cross section and placed 1m apart in a vacuum, would produce a force on each conductor of 2x10-7 per meter of length

define "electromagnetic induction"

the phenomenon which occurs when the magnetic field passing through a coil changes and an EMF appears in the coil

define "magnetic flux"

Ammount of magnetic force passing though an area


define "weber"

if the magnetic flux density over an area of one meter squared is one tesla then the flux through the area is 1 weber



state Faraday's law of electromagnetic induction

the size of the induced EMF is directly proportional to the rate of change of flux


state Lenz's law

the direction of an induced current is always such as to oppose the change producing it

define "Mutual induction"

there is said to be mutual induction between 2 coils if a changing magnetic field in one coil causes an induced EMF to appear in a nearby coil

`define "self induction"

whenever the current passing through a coil changes, the coil's surrounding magnetic field changes. This changing field induces an EMF in the coil that opposes the changing current

define "thermionic emission"
the giving off of electrons from the surface of a hot metal
define "cathode rays"
streams of high-speed electrons moving from a cathode


define "the electron-volt"
the amount of energy gained or lost by an electron when it moves through a potential difference of 1 volt
state the "photoelectric effect"
the emission of electrons from the surface of a metal by electromagnetic radiation of a suitable frequency


what is a "photocell"
a device which conducts current when light of a suitable frequency shines on it
what is the "threshold frequency" for a given metal
the frequency below which photo emission won't occur
define "work function"
the minimum energy needed to remove the loosest electron from the surface of a metal


state Einstein's Photoelectric Law
the maximum energy of an electron is

HF - WORK FUNCTION (H=Planck's constant and F= frequency of the incident radiation)

define "X-Rays"
electromagnetic radiation of high frequency produced when cathode rays (rays of electrons) strike a metal target with a high melting point
what is an "emission spectra"
when light from a luminous source undergoes dispersion, this is the resulting pattern
What does "Laser" stand for
Light Amplification by Stimulated Emission of Radiation


what is an "isotope"
atoms of an element that have the same number of protons but a different number of neutrons
define "radioactivity"
the disintegration of decay of the nuclei of certain atoms with the emission of one or more types of radiation


what is the "activity" of a radioactive substance
the number of nuclei of that substance decaying per second
state the "law of radioactive decay"
the number of nuclei decaying per second (ie activity) is directly proportional to the number of nuclei undecayed
what is the "half life" of a radioactive isotope
-the time taken for half of the undecayed atoms to undergo decay

-the time taken for its activity to be decreased by half

define "nuclear fission"
the splitting up of a large nucleus into two smaller nuclei of roughly the same size
define "critical size"
the size of the sample in which a chain reaction can occur
define "nuclear fusion"
the joining of two small nuclei to form a large nucleus