A Level Definition Bank

12. Motion in a Circle

Radian (1)

9702_s25_qp_42-Q1.a

Question

Define the radian.

Mark Scheme

Angle subtended at centre of circle when arc length is equal to radius of the circle

Angular Velocity (2)

9702_w10_qp_43-Q1.a.i

Question

State what is meant by angular velocity.

Mark Scheme

Rate of change of angle

swept out by radius

Centripetal Acceleration (1)

9702_w21_qp_42-Q1.a

Question

State what is meant by centripetal acceleration.

Mark Scheme

Acceleration perpendicular to velocity

Circular Motion

9702_w25_qp_41-Q1

Question

In terms of velocity and acceleration, describe uniform circular motion of an object.

Mark Scheme

Velocity and acceleration both have constant magnitude

Acceleration is always towards centre of circular path

Velocity is always perpendicular to acceleration

13. Gravitational Fields

Field of Force

Field of Force (2)

9702_w17_qp_42-Q9.a

Question

State what is meant by a field of force.

Mark Scheme

Region of space where a particle experiences a force

Gravitational Field (1)

9702_w25_qp_41-Q3.a

Question

Define gravitational field at a point.

Mark Scheme

Force per unit mass

Gravitational Field Line (2)

9702_s25_qp_42-Q2.a.i

Question

State what is represented by a gravitational field line.

Mark Scheme

Direction of force

acting on a test mass

Gravitational Field Strength (1)

9702_w18_qp_42-Q1.a.i

Question

State what is meant by gravitational field strength.

Mark Scheme

Force per unit mass

Newton's Law of gravitation (2)

9702_w25_qp_44-Q1.a

Question

State Newton’s law of gravitation.

Mark Scheme

Gravitational force between two point masses is directly proportional to the product of their masses

and inversely proportional to the square of their separation

Features of geostationary orbit (3)

9702_m19_qp_42-Q4.a

Question

State three features of the orbit of a geostationary satellite.

Mark Scheme

Orbit is above the equator

Orbital period of 24 hours

Orbits west to east

One particular orbital radius

Gravitational Potential at a point (2)

9702_s25_qp_41-Q1.a

Question

Define gravitational potential at a point.

Mark Scheme

Work done per unit mass

in moving a small test mass from infinity to a point

14. Temperature

Thermal Equilibrium (2)

9702_s25_qp_44-Q2.a

Question

State what is meant by two objects being in thermal equilibrium.

Mark Scheme

Same temperature as each other

no net transfer of thermal energy between them

Absolute Zero (2)

9702_w11_qp_43-Q2.b.ii

Question

what is meant by the absolute zero of temperature.

Mark Scheme

Temperature at which atoms have zero energy

Equivalent to -273.15 degrees Celsius

Specific Heat Capacity (1)

9702_s25_qp_42-Q3.a

Question

Define specific heat capacity.

Mark Scheme

Thermal energy per unit mass per unit change in temperature

Specific latent heat (2)

9702_s25_qp_41-Q3.a

Question

Define specific latent heat.

Mark Scheme

Thermal energy per unit mass to cause state change

at constant temperature

Specific latent heat of fusion (2)

9702_w08_qp_4-Q2.a

Question

Define specific latent heat of fusion.

Mark Scheme

Thermal energy per unit mass

to change state from solid to liquid at constant temperature

Specific latent heat of vaporisation (2)

9702_s22_qp_42-Q3.a

Question

Define specific latent heat of vaporisation.

Mark Scheme

Thermal energy per unit mass

to change state from liquid to gas at constant temperature

15. Ideal Gases

Ideal Gas (2)

9702_s25_qp_44-Q3.a

Question

State what is meant by an ideal gas.

Mark Scheme

A gas that obeys the relationship $p V \propto T$ for all values of p, V, and T

where T is the thermodynamic temperature

Assumptions of Kinetic Theory of Gases (2)

9702_w25_qp_42-Q2.b

Question

State two basic assumptions of the kinetic theory of gases.

Mark Scheme

No forces of attraction between molecules

Molecules have negligible volume compared with volume of gas

Collisions involving molecules are perfectly elastic

Collisions of molecules are instantaneous

Molecules are in continuous random motion.

Mole (2)

FROM CHEMISTRY!

Question

Define the mole.

Mark Scheme

Amount of substance

containing Avogadro’s number of particles

Avogadro's Constant (1)

9702_w24_qp_41-Q3.a.i

Question

State what is meant by the Avogadro constant.

Mark Scheme

Number of particles per unit amount of substance

16. Thermodynamics

Internal energy of ideal gas (2)

9702_w25_qp_44-Q3.a, 9702_m24_qp_42-Q2.a

Question

With reference to molecular kinetic energy and molecular potential energy, explain what is meant by the internal energy of an ideal gas.

Mark Scheme

Total kinetic energy associated with the random motion of molecules

plus total potential energy of molecules but potential energy is zero

Internal energy of a system (2)

9702_s25_qp_41-Q4.a.i

Question

State what is meant by the internal energy of a system.

Mark Scheme

Sum of potential energy and kinetic energy

total energy of random motion of particles

First law of thermodynamics (2)

9702_w25_qp_42-Q4.a

Question

State the first law of thermodynamics.

Mark Scheme

change in internal energy = work done + energy transfer by heating

increase in internal energy = work done on system + energy transferred to the system by heating.

17. Oscillations

Simple harmonic motion (2)

9702_s25_qp_42-Q5.a

Question

State what is meant by simple harmonic motion.

Mark Scheme

Motion in which acceleration is directly proportional to displacement

and acceleration is always in opposite direction to displacement.

Angular frequency (1)

9702_w17_qp_41-Q2.a

Question

State, by reference to simple harmonic motion, what is meant by angular frequency.

Mark Scheme

Angular frequency = $2 π \times frequency$

Damping (2)

9702_w25_qp_42-Q5.b.i

Question

State what is meant by damping.

Mark Scheme

Loss of energy of oscillations

due to resistive forces

Resonance (2)

9702_s22_qp_42-Q4.a

Question

State what is meant by resonance.

Mark Scheme

Oscillations of object are at maximum amplitude

when driving frequency equals natural frequency of object

Natural frequency (2)

9702_m18_qp_42-Q4.a

Question

Explain what is meant by the natural frequency of vibration of a system.

Mark Scheme

Frequency at which a body will vibrate when there is no external force acting on it

18. Electric fields

Electric field (1)

9702_w25_qp_42-Q6.a

Question

Define electric field at a point.

Mark Scheme

force per unit positive charge

Electric field line (2)

9702_m22_qp_42-Q4.a

Question

State what is represented by an electric field line.

Mark Scheme

Direction of force

on a positive charge

Electric field strength (1)

9702_s19_qp_41-Q5.a

Question

State what is meant by electric field strength.

Mark Scheme

Force per unit positive charge

Coulomb's law

9702_s25_qp_41-Q2.a

Question

State Coulomb’s law.

Mark Scheme

Electric force between two point charges is directly proportional to the product of their charges

and inversely proportional to the square of their separation

Electric potential (2)

9702_s24_qp_42-Q5.a

Question

Define electric potential at a point.

Mark Scheme

Work done per unit charge

in brining positive charge from infinity to a point

19. Capacitance

Capacitance (Isolated Conductor) (1)

9702_m16_qp_42-Q7.a

Question

Define capacitance

Mark Scheme

Charge per unit potential difference

Capacitance of parallel plate capacitor (2)

9702_w24_qp_42-Q7.a

Question

Define the capacitance of a parallel‑plate capacitor.

Mark Scheme

Ratio of charge on one plate

to potential difference between the plates

20. Magnetic fields

Magnetic field (1)

9702_m20_qp_42-Q8.a

Question

Explain what is meant by a magnetic field.

Mark Scheme

Region of space where a moving charge experiences a force

Magnetic flux density (2)

9702_s25_qp_41-Q7.a

Question

Define magnetic flux density.

Mark Scheme

Force per unit length

per unit current

Where length and current are perpendicular to magnetic field

2 marks for all 3 points

Tesla (2)

9702_w21_qp_41-Q8.a

Question

Define the tesla.

Mark Scheme

Newton per ampere per metre

where current is perpendicular to magnetic field

Magnetic Flux (2)

9702_m18_qp_42-Q10.a.i

Question

Define magnetic flux.

Mark Scheme

Product of magnetic flux density and area

where direction of flux is normal to area

Magnetic flux linkage (2)

9702_m21_qp_42-Q9.a

Question

Define magnetic flux linkage.

Mark Scheme

Product of magnetic flux density and area and number of turns

where area is perpendicular to magnetic field

Faraday's law of electromagnetic induction (2)

9702_m25_qp_42-Q7.a

Question

State Faraday’s law of electromagnetic induction.

Mark Scheme

Induced e.m.f. is directly proportional

to rate of change of magnetic flux linkage

Induced e.m.f. not magnitude of induced e.m.f.

Lenz's law of electromagnetic induction (2)

9702_w25_qp_44-Q7.a

Question

State Lenz’s law of electromagnetic induction.

Mark Scheme

Direction of induced e.m.f.

is such as to produce effects that oppose the change that caused it

21. Alternating currents

Frequency of an alternating current (1)

9702_w24_qp_42-Q8.a

Question

State what is meant by the frequency of an alternating current.

Mark Scheme

Number of cycles per unit time

Root-mean-square value of an AC voltage (1)

9702_w21_qp_41-Q9.a

Question

State, by reference to the power dissipated in a resistor, what is meant by the root-mean-square (r.m.s.) value of an alternating voltage.

Mark Scheme

Constant voltage

that dissipates same power as the mean power of the alternating voltage

Rectification of an alternating voltage (1)

9702_w24_qp_41-Q6.a.i

Question

State what is meant by rectification of an alternating voltage.

Mark Scheme

Conversion from AC to DC

Smoothing (1)

9702_w11_qp_43-Q5.c.i

Question

what is meant by smoothing,

Mark Scheme

Reduction in the variation of the output voltage of a rectification circuit

22. Quantum Physics

Photon (2)

9702_w25_qp_41-Q8.a

Question

State what is meant by a photon.

Mark Scheme

Quantum of energy

of electromagnetic radiation

Photoelectric effect (2)

9702_s25_qp_42-Q9.a

Question

State what is meant by the photoelectric effect.

Mark Scheme

Emission of electrons from a metal surface

when electromagnetic radiation is incident on the surface

Threshold frequency (2)

9702_m16_qp_42-Q11.a

Question

With reference to the photoelectric effect, state what is meant by the threshold frequency.

Mark Scheme

Minimum frequency of electromagnetic radiation needed

for emission of electrons from a metal surface to occur

Work function energy (2)

9702_w22_qp_41-Q8.a

Question

State what is meant by the work function energy of a metal.

Mark Scheme

Minimum photon energy

to remove an electron from the surface of a metal

Wave particle duality (2)

9702_s25_qp_44-Q9.a.i

Question

Describe what is meant by wave–particle duality.

Mark Scheme

Electromagnetic wave can behave like a particle

moving particle can behave like a wave

de Broglie wavelength (1)

9702_s25_qp_41-Q8.a

Question

State what is meant by the de Broglie wavelength.

Mark Scheme

Wavelength associated with a moving particle

23. Nuclear physics

Isotopes (2)

9702_s12_qp_42-Q8.a

Question

State what is meant by isotopes

Mark Scheme

Nuclei of the same element having same number of protons

but different number of neutrons

Mass defect of a nucleus (2)

9702_w25_qp_42-Q9.a

Question

State what is meant by the mass defect of a nucleus.

Mark Scheme

Difference between mass of nucleus and mass of constituent nucleons

when nucleons are separated to infinity

Nuclear binding energy (2)

9702_s24_qp_42-Q9.a

Question

State what is meant by the binding energy of a nucleus.

Mark Scheme

Energy required to separate all the nucleons in the nucleus

to infinity

Nuclear fusion (2)

9702_w23_qp_41-Q9.a

Question

State what is meant by nuclear fusion.

Mark Scheme

Two small nuclei join together

to form one large nucleus

Nuclear fission (2)

9702_w20_qp_42-Q12.a.ii

Question

Explain what is meant by a nuclear fission reaction.

Mark Scheme

A single large nucleus divides to form smaller nuclei

total binding energy increases

Radioactive decay (3)

9702_w18_qp_41-Q12.a

Question

State what is meant by radioactive decay.

Mark Scheme

Spontaneous emission

of particles or photons

from an unstable nucleus

Random nature of radioactive decay (1)

9702_m25_qp_42-Q9.a

Question

Radioactive decay is both random and spontaneous. State what is meant by: (i) random

Mark Scheme

Cannot predict when a particular nucleus will decay

Spontaneous nature of radioactive decay (1)

9702_m25_qp_42-Q9.a

Question

Radioactive decay is both random and spontaneous. State what is meant by: spontaneous

Mark Scheme

Not affected by external factors

Activity of a radioactive sample (1)

9702_w25_qp_44-Q8.c.i

Question

Define the activity of a sample.

Mark Scheme

number of nuclear disintegrations per unit time

Decay constant (2)

9702_m18_qp_42-Q13.a.i

Question

Define radioactive decay constant.

Mark Scheme

probability of decay of a nucleus

per unit time

Half life (1)

9702_m25_qp_42-Q9.b

Question

Define half‑life.

Mark Scheme

time for activity to halve

24. Medical Physics

Specific acoustic impedance (2)

9702_s25_qp_44-Q10.b.i

Question

State what is meant by specific acoustic impedance.

Mark Scheme

Product of density of medium

and speed of ultrasound in medium

Attenuation of ultrasound wave (2)

9702_w19_qp_42-Q5.c.i

Question

State what is meant by attenuation of an ultrasound wave.

Mark Scheme

Reduction in intensity of wave

as the wave passes through a medium

Contrast of an X-ray image (1)

9702_w15_qp_41-Q10.a

Question

Explain what is meant by the contrast of an X-ray image.

Mark Scheme

difference in degree of blackening of structures

Tracer (2)

9702_w25_qp_44-Q8.a

Question

State what is meant by a tracer.

Mark Scheme

Radioactive substance introduced into the body

which is absorbed by the tissues being studied

Annihilation (1)

9702_m22_qp_42-Q11.b.i

Question

Explain what is meant by annihilation.

Mark Scheme

A particle interacting with its antiparticle so that the mass is converted into energy

25. Astronomy and cosmology

Luminosity of a star (1)

9702_m25_qp_42-Q10.a.i

Question

State what is meant by the luminosity of a star.

Mark Scheme

total power of radiation emitted by the star

Standard candle (1)

9702_m23_qp_42-Q10.b

Question

State what is meant by a standard candle.

Mark Scheme

Object with known luminosity

Wien's displacement law (2)

9702_w25_qp_41-Q9.a

Question

State Wien’s displacement law.

Mark Scheme

Temperature is inversely proportional to wavelength

Where temperature is thermodynamic temperature of surface of star

and wavelength is the wavelength at which maximum emission rate from star occurs

2 marks for all 3 points

Redshift (2)

9702_w25_qp_44-Q10.a

Question

State what is meant by redshift.

Mark Scheme

Recession of galaxy from observer causes emitted light to have

increase in observed wavelength

Hubble's Law (2)

9702_s25_qp_41-Q10.a

Question

State Hubble’s law.

Mark Scheme

Speed is directly proportional to distance

where speed is speed of recession of galaxy from observer

and distance is the distance of the galaxy from the observer

2 marks for 3 points

Physics

Explorer

9702-P4_definition_bank

A Level Definition Bank

12. Motion in a Circle

13. Gravitational Fields

14. Temperature

15. Ideal Gases

16. Thermodynamics

17. Oscillations

18. Electric fields

19. Capacitance

20. Magnetic fields

21. Alternating currents

22. Quantum Physics

23. Nuclear physics

24. Medical Physics

25. Astronomy and cosmology

12. Motion in a Circle

13. Gravitational Fields

Field of Force

14. Temperature

15. Ideal Gases

16. Thermodynamics

17. Oscillations

18. Electric fields

19. Capacitance

20. Magnetic fields

21. Alternating currents

22. Quantum Physics

23. Nuclear physics

24. Medical Physics

25. Astronomy and cosmology

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