H1/H2 Physics Definition Booklet
1. Measurement
No.
1
Term
Base Quantities
2
Derived
Quantities
Homogeneous
Equation
3
4
Systematic Error
5
Random error
6
Accuracy
7
Precision
8
9
Scalar
Vector
1
2
Distance
Displacement
3
4
5
6
Speed
Velocity
Acceleration
Free Fall
Updated Sep 2015
Definitions
Base quantities are quantities that can be accurately and easily
reproduced and are unchanging with time.
Derived quantities are quantities that are obtained from the
multiplication or division of base quantities.
A physical equation is said to be homogeneous if each of the
terms, separated by plus, minus, equality or inequality signs
has the same base units.
An error is systematic if repeating the measurement under
the same conditions yields readings with error of same
magnitude and sign.
An error is random if repeating the measurement under the
same conditions yields readings with error of different
magnitude and sign. Readings with random error spread over
a certain range within which a mean value may be
determined.
The accuracy of an experiment is a measure of how close the
result of an experiment comes to the true value. The
accuracy of an experiment is generally dependent of how well
we can control or compensate for systematic errors.
The precision of an experiment is a measure of how exactly
the result is determined without reference to what that result
means.
The smaller the uncertainty of the measurement, the more
precise is the measurement. The precision of an experiment
is dependent on how well we can minimize random errors.
A scalar is a physical quantity which has magnitude only.
A vector is a physical quantity which has both magnitude and
direction.
2. Kinematics
Distance is the length of the path taken.
Displacement is the distance travelled along a specified
direction.
Speed is the rate of change of distance.
Velocity is the rate of change of displacement.
Acceleration is the rate of change of velocity.
In the absence of air resistance, an object is said to be in free
fall if the only force acting on it is the gravitational force of the
Earth.
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H1/H2 Physics Definition Booklet
3. Forces
1
Hooke’s Law
2
Moment of a
Force
3
Couple
4
Torque
5
Equilibrium
6
Stable
Equilibrium
Unstable
Equilibrium
7
8
Rigid Body
9
Centre of Mass
10
Centre of gravity
11
Archimedes’
Principle
Principle of
Flotation
12
1
2
3
4
Hooke’s Law states that within the limit of proportionality, the
extension produced in a material is directly proportional to the
load applied.
Moment is defined as the product of the force and the
perpendicular distance between the axis of rotation and the line
of action of the force.
A couple is a pair of forces, equal in magnitude but opposite in
direction but their lines of action do not coincide
Torque is the moment of a couple. It is the product of one of the
forces and the perpendicular distance between their lines of
action
An object is said to be in equilibrium if the resultant force
acting on it is zero and the resultant torque acting on the
object about every axis is zero.
A body is said to be in stable equilibrium if it returns to its
original position after it has been displaced slightly.
An object is in unstable equilibrium if any displacement from
its original position lowers its centre of gravity. Toppling
occurs when the centre of gravity of an object falls outside its
base.
One that does not change its shape appreciably when
undergoing acceleration.
The centre of mass of a body is the single point at which the
entire mass of the body can be considered to act
The centre of gravity of a body is the single point at which the
entire weight of the body can be considered to act.
When an object is immersed in a fluid, it experiences an
upthrust which is equal to the weight of fluid displaced by it.
For a body floating in equilibrium, the weight of the fluid
displaced is equal to the weight of the body.
4. Dynamics
Newton's first
law of motion
Newton's first law of motion states that a body will remain in
its state of rest or uniform motion in a straight line unless
acted upon by a resultant force.
Newton's second Newton's second law of motion states that the rate of change
law of motion
of momentum of a body is proportional to the resultant force
acting on it and the change takes place in the direction of the
resultant force.
Newton's third
Newton's third law of motion states that if body A exerts a
law of motion
force on body B, then body B exerts an equal and opposite
force on body A.
Inertia
Inertia is the property of a body that resists change in motion.
Updated Sep 2015
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H1/H2 Physics Definition Booklet
5
Mass
6
7
Linear
Momentum
1 Newton
8
Impulse
9
10
Principle of
Conservation of
Momentum
Elastic collision
11
Inelastic collision
12
Completely
inelastic collision
1
Work Done
2
1 Joule
3
4
Energy
Principle of
Conservation of
Energy
5
Kinetic Energy
6
Potential Energy
7
Internal Energy
8
Work-Energy
Theorem
9
Principle of
Conservation of
Mechanical
Updated Sep 2015
Mass is a measure of the amount of substance/inertia of the
body.
The linear momentum of a body is defined as the product of
its mass and its velocity.
1 Newton is defined as the force which, when acting on a 1
kilogram mass, produces an acceleration of 1 m s-2.
Impulse is the product of the force acting on a body and the
time interval during which the force is exerted. (The impulse
of the force acting on a body is equal to the change in
momentum of the body.)
The principle of conservation of momentum states that the
total momentum of a system remains constant if no resultant
external force acts on the system.
Elastic collision in which both momentum and kinetic energy
are conserved.
Inelastic collision in which momentum is conserved but
kinetic energy is not.
Completely inelastic collision in which momentum is
conserved and the particles stick together after collision so
that their final velocities are the same
5. Work, Energy and Power
Work done W is defined as the product of the force F and the
displacement s made in the direction of the force.
1 joule is defined as the work done by a force of 1 newton
when its point of application moves through a distance of 1
metre in the direction of the force.
Energy is defined as the stored ability to do work.
The Principle of Conservation of Energy states that energy
can neither be created nor destroyed in any process. It can
be transformed from one form to another, and transferred
from one body to another but the total amount remains
constant.
Kinetic Energy is defined as the energy of a body by virtue of
its motion.
Potential Energy is defined as the energy of a body by virtue
of its position.
Internal energy of a gas is the sum of random distribution of
kinetic and potential energies of the molecules of a system.
The Work-Energy Theorem states that the net work done by
external forces acting on a particle is equal to the change in
kinetic energy of the particle.
When work is done by conservative forces, the total
mechanical energy (ie. total kinetic energy and potential
energy) of a system is conserved. In other words, the gain in
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H1/H2 Physics Definition Booklet
Energy
10
Power
1
Radian
2
Angular
Displacement
3
Angular Velocity
4
Period, T
1
Newton's law of
gravitation
2
Gravitational
Field
Gravitational
Field Strength, g
Gravitational
potential energy,
U
Gravitational
potential, 𝜙
3
4
5
6
Equipotential
7
Escape Speed
1
Oscillation or
Oscillatory
motion
Simple harmonic
motion
2
3
Amplitude
Updated Sep 2015
kinetic energy is equal to the loss in potential energy for the
conservative system and vice versa.
Power is defined as the rate of doing work.
6. Circular Motion
One radian is the angle subtended by an arc length of 1 m in
a circle of radius 1 m.
Angular displacement  is defined as the angle an object
makes with respect to a fixed point. For circular motion, this
point is taken to be the centre of the circle.
Angular velocity ω is defined as the rate of change of angular
displacement or the change in angular displacement per unit
time.
Time taken to complete one revolution
7. Gravitation
Newton's law of gravitation states that two point masses
attract each other with a force that is proportional to the
product of their masses and inversely proportional to the
square of the distance between them.
The gravitational field is a region of space whereby a test
mass placed in it experiences a force.
The gravitational field strength at a point is defined as the
gravitational force per unit mass at that point.
Gravitational potential energy U at a point is defined as the
work done by an external agent in bringing a body from
infinity to that point (without any change in its kinetic energy).
Gravitational potential  at a point is defined as the work done
per unit mass by an external agent in bringing a body from
infinity to that point (without any change in its kinetic energy).
Equipotential surfaces are surfaces on which the potential is
the same at all points.
Escape speed is the minimum speed at which a body can be
projected from the surface of a planet so that it reaches an
infinite distance from the planet.
8. Oscillation
An oscillation or oscillatory motion is a motion in which a
system moves back and forth along the same path
repeatedly.
Simple harmonic motion is as an oscillatory motion of a
particle whose acceleration is directly proportional to its
displacement from the equilibrium position and this
acceleration is always directed towards that position.
The amplitude xo is the maximum displacement of the
oscillating particle from the equilibrium position.
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H1/H2 Physics Definition Booklet
4
5
6
Period
Frequency
Phase difference
The time taken for one complete oscillation.
The number of complete oscillation per unit time.
Phase difference , is the difference in the phase angle
between the two oscillations which have the same frequency.
7
Damped
Oscillation
8
Light or under
damping
9
Heavy or over
damping
10
Critical damping
11
Forced
Oscillation
12
Resonance
A damped oscillation is one that is subjected to frictional or
dissipative forces like air resistance, so that the amplitude of
the oscillation and hence the total energy of the system
decreases with time.
Light or under damping: The dissipative force is minimal.
Definite oscillations occur and the amplitude of oscillation
decays exponentially with time.
Heavy or over damping: Large dissipative force. No
oscillation occurs and the system returns very slowly to
equilibrium.
Critical damping: Suitable dissipative conditions so that the
system returns to equilibrium without overshooting in the
shortest possible time
When an oscillating system is subjected to this external
oscillatory force, the system will oscillate with a frequency
equal to the driving frequency, and forced oscillation is said to
have occurred.
Resonance is said to have taken place when the driving
frequency of the external oscillatory force is equal to the
natural frequency of the oscillating system. The driving
oscillator most easily transfers its energy to the oscillating
system. The energy of the system becomes a maximum and
the system will oscillate with maximum amplitude
9. Waves
1
Wave
2
Progressive
Waves
3
Transverse
Waves
4
Longitudinal
Waves
5
Polarisation
6
Wavelength

Updated Sep 2015
A wave is a propagation of a disturbance which carries
energy(and momentum) from one point in space (and time) to
another.
A progressive or travelling wave is the movement of a
disturbance from a source which transfers energy but not
material to places around it.
Transverse waves are waves in which the displacement of
the particles of the medium is perpendicular to the direction of
the transfer of energy.
Longitudinal waves are waves in which the displacement of
the particles of the medium is parallel to the direction of the
transfer of energy.
A wave is plane polarized if the oscillations in the wave are
confined to one direction only.
The wavelength is the distance between any two successive
points which are in phase.
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H1/H2 Physics Definition Booklet
7
8
9
Wave speed
Wavefront
Phase difference
10
Intensity of a
wave
11
Stationary or
standing wave
When two progressive waves of equal amplitude and equal
frequency travelling with the same speed in opposite
directions are superposed, a stationary or standing wave is
formed.
10. Superposition
1
Principle of
Superposition
2
Diffraction
3
Interference
4
Coherent
When two or more waves of the same kind exist
simultaneously at a point in space, the resultant displacement
of the waves at any point is the vector sum of the
displacement due to each wave acting independently.
Diffraction is the spreading of waves around an obstacle or
through a gap, into its geometrical shadow.
Interference occurs when two or more waves of the same
kind meet at a point and superpose to produce a resultant
wave. The displacement of the resultant wave at any point is
given by the Principle of Superposition.
Waves from each source have the same frequency and a
constant phase difference between them.
11. Thermal Physics
1
Temperature
2
Thermal
Equilibrium
3
Zeroth law of
thermodynamics
4
Absolute zero
5
Triple point of
water
6
One kelvin
7
Internal energy,

Updated Sep 2015
Distance the wave profile moves per unit time.
A line or surface joining points of a wave that are in phase.
Phase difference  is a measure, in angular form, of the
fraction of a cycle two particles in a waves or two waves are
out of step by in their motion.
Intensity of a wave is defined as the rate of energy flow per
unit cross-sectional area perpendicular to the direction of
wave propagation.
Temperature is defined as a measure of the average kinetic
energy of molecules in a body.
Two bodies are said to be in thermal equilibrium when they
are in thermal contact and there is no net flow of heat from
one body to another. It also means that the two bodies are at
the same temperature
Zeroth law of thermodynamics states that if bodies A and B
are separately in thermal equilibrium with a third body C, then
A and B are in thermal equilibrium with each other.
Absolute zero (0 K) is the temperature at which the pressure
of an ideal gas becomes zero.
Triple point of water (273.16 K) is the temperature at which
the three phases of water (i.e. ice, water and water vapour)
coexist in dynamic equilibrium.
One kelvin is defined to be 1/273.16 of the thermodynamic
temperature of the triple point of water
Internal energy, U of a body can be defined as the sum of the
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H1/H2 Physics Definition Booklet
U
8
9
10
11
12
13
14
15
16
17
18
19
1
kinetic energy of all the atoms (molecules) due to their
random motion and the potential energy of all the atoms
(molecules) due to their positions relative to each other and
the forces between them.
Heat capacity, C of a body is defined as the quantity of heat
Heat capacity
absorbed or liberated, Q, by the body per unit temperature
change
Specific heat capacity of a material, c is defined as the
Specific heat
quantity of heat absorbed or liberated, Q, per unit mass of the
capacity
material per unit temperature change
Latent heat
Latent heat is defined as the quantity of heat absorbed or
liberated by a substance in order to change a substance from
one phase to another phase without a temperature change.
Specific latent heat of fusion of a substance, Lf is defined as
Specific latent
heat of fusion
the quantity of heat required per unit mass to change the
substance from the solid phase to the liquid phase without a
change in temperature.
Specific latent heat of vaporization of a substance, Lv is
Specific latent
heat of
defined as the quantity of heat required per unit mass to
vaporization
change a substance from the liquid phase to the vapour
phase without a change in temperature
Evaporation
Evaporation is the process by which a liquid, at any
temperature, becomes vapour.
Boyle’s Law
The pressure of a fixed mass of gas is inversely proportional
to its volume if the temperature is constant. (isothermal
process)
Charles’ Law
The volume of a fixed mass of gas is directly proportional to
its absolute temperature if its pressure is kept constant.
(isobaric process)
Gay-Lussac’s
The pressure of a fixed mass of gas is directly proportional to
its absolute temperature if its volume is kept constant.
Law (Pressure
Law)
(isovolumetric/isochoric/isometric process)
An ideal gas is one which obeys the equation pV = nRT, at all
Ideal Gas
pressures, volumes and temperatures.
One Mole
One mole is the amount of substance which contains the
same number of elementary entities as there are atoms in 12
g of carbon-12.
The First Law of The First Law of Thermodynamics states that the internal
Thermodynamics energy of a system is a function of its state. The increase in
internal energy of a system is equal to the sum of the heat
absorbed by the system and the work done on the system
12. Electric Field
Coulomb's Law
Updated Sep 2015
Coulomb's Law states that the electric force between two
point charges is proportional to the product of their charges
and inversely proportional to the square of the distance
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H1/H2 Physics Definition Booklet
2
Electric field
3
Electric Field
Strength
Electric Potential
V
4
5
Electric Potential
Energy U
6
Equipotential
Surface
1
Charge
2
3
Electric current
Coulomb
4
Electromotive
Force (e.m.f)
5
Potential
difference (p.d.)
6
One Volt
7
Electrical
Resistance
8
One Ohm
9
Ohm’s Law
Updated Sep 2015
between them.
An electric field is a region of space where a stationary
charge placed anywhere in it experiences a force.
The electric field strength at a point is defined as the electric
force acting per unit positive charge placed at that point.
The electric potential V at a point is defined as the work done
per unit positive charge by an external agent in bringing a
charged body from infinity to that point
The electric potential energy U at a point is defined as the
work done by an external agent in bringing a charged body
from infinity to that point.
An equipotential surface is one on which all the points have
the same potential.
13. Current of Electricity
Charge is the property of a particle that causes an interaction
of the particle with other charged particles and material of
electrical nature.
Electric current is the rate of flow of charge.
The coulomb is defined as the charge which passes a section
of a circuit when a steady current of one ampere flows for
one second.
Electromotive force (e.m.f.) of a source of electrical energy is
defined as the energy converted from other forms (e.g.
chemical, mechanical) into electrical energy per unit charge
passing through it.
Potential Difference (p.d.) across an electrical device in a
circuit is defined as the amount of electrical energy converted
to other forms of energy (e.g. heat and light) per unit charge
passing through it.
One volt is defined as the p.d. across a device in a circuit if
one joule of electrical energy is converted to other forms of
energy per coulomb of charge passing through it.
Electrical resistance of a conductor is defined as the ratio of
the potential difference across it to the current flowing
through it.
One Ohm is defined as the resistance of a conductor per
ampere of current flowing through when the p.d. across it is
one volt.
Ohm’s Law states that the current through a metallic
conductor is directly proportional to the potential difference
across it, provided the temperature and other physical
conditions are kept constant.
14. DC Circuit (No definition)
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H1/H2 Physics Definition Booklet
15. Magnetic Fields and Electromagnetism
1
Magnetic Field
2
Magnetic Flux
Density
3
One Tesla
1
Magnetic Flux
2
One weber
3
Faraday’s Law
4
Lenz’s Law
1
Root Mean
The root mean square value of an a.c. is defined as the value
Square of an a.c. of the steady direct current that would dissipate heat at the
same rate as the a.c. in a given resistor.
Rectification
A process converting a d.c. to an a.c.
18. Quantum Physics
2
1
2
3
4
5
A magnetic field is a region of space where a magnet will
experience a force.
The magnetic flux density at a point is defined as the force
acting per unit current per unit length of the conductor when
the conductor is placed at right angles to the field.
One tesla is the uniform magnetic flux density which, acting
normally to a long straight wire carrying a current of 1
ampere, causes a force per unit length of 1 𝑁𝑚−1 on the
conductor.
16. Electromagnetic Induction
The magnetic flux through a plane surface is the product of
the flux density normal to the surface and the area of the
surface.
One weber is the quantity of magnetic flux passing through
an area of 1 square metre when the flux density normal to the
area is 1 tesla.
Faraday’s Law states that the induced e.m.f. in a circuit is
directly proportional to the rate of change of flux-linkage or to
the rate of cutting of magnetic flux.
Lenz’s Law states that the direction of the induced e.m.f. is
such that it tends to oppose the flux change causing it, and
does oppose it if induced current flows
17. Alternating Current
Planck’s
Quantum Theory
Planck’s Quantum Theory states that light is emitted and
absorbed as particles or discrete packets of energy called
photons.
Photon
A photon is a quantum of electromagnetic radiation with
discrete package of energy.
Photoelectric
Photoelectric effect is the emission of electrons from the
effect
surface of a metal when electromagnetic radiation of
sufficiently high frequency is shone on it.
Work function
Work function is the minimum amount of energy required for
an electron to escape from the surface of a metal
Ionization energy The ionization energy of an atom is the energy required to
remove the electron completely from the atom
Updated Sep 2015
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H1/H2 Physics Definition Booklet
6
Transmission
Coefficient, T
7
Reflection
Coefficient, R
1
Absorption
2
Spontaneous
emission
3
Stimulated
emission
4
5
Population
Inversion
Metastable State
6
Forbidden band
7
8
Valence band
Conduction band
9
Energy gap
1
Nucleon number
(or mass
number), A
Proton number
(or atomic
number), Z
2
3
4
Neutron number,
N
Isotopes
Updated Sep 2015
The transmission coefficient T represents the probability with
which an approaching particle will penetrate to the other side
of the barrier
The reflection coefficient R represents the probability with
which an approaching particle will be reflected by the barrier.
19. Laser and Semiconductor
Absorption is the process whereby the energy of a photon is
absorbed by an atom causing the atom to make a transition
from the ground state to a higher energy level.
Spontaneous emission is the process whereby an atom in an
excited state makes a transition on its own accord to a lower
energy level, emitting a photon.
Stimulated emission is the process whereby an incident
photon causes an atom in an excited state to return to its
ground state with the emission of an additional photon. The
emitted photon has the same energy, phase, frequency and
travels in the same direction as the incident photon.
The condition of having more atoms in an excited state than
in the lower state is called population inversion.
Metastable State is the state in which the electrons remain
longer than usual so that the transition to the lower state
occurs more likely by stimulated emission than by
spontaneously emission.
Forbidden band represents a region where no electron state
is allowed.
Valence band is the highest populated band that is full.
Conduction band is the empty or partially filled band that is
just above the valence band.
The energy separation between the valence and conduction
bands is known as the energy gap of the material.
20. Nuclear Physics
Nucleon number (or mass number), A, is the sum of the
number of protons and neutrons (i.e. the number of nucleons)
in the nucleus.
Proton number (or atomic number), Z, of an element is the
number of protons in the nucleus. Therefore, it is also equal
to the number of electrons in a neutral atom. It defines the
chemical characteristics of an atom and the place of the
element in the periodic table.
Neutron number, N, of an element is the number of neutrons
in the nucleus.
Isotopes are atoms of the same element with the same
number of protons but different number of neutrons. They are
chemically the same, but have different masses.
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H1/H2 Physics Definition Booklet
5
1u
6
Binding energy
of a nucleus
7
Binding energy
per nucleon
8
Nuclear fission
9
Nuclear fusion
10
Radioactivity
11
Spontaneous
12
Random
13
14
Rate of
disintegration or
Activity A
Decay constant
15
Half-life t1/ 2

1 u is defined such that the mass of carbon-12 is exactly 12
u.
The binding energy of a nucleus is defined as the energy
released when the nucleus is formed from its separate
protons and neutrons.
The binding energy per nucleon of a nucleus is the binding
energy of the nucleus divided by the nucleon number of the
nucleus.
Nuclear fission is the disintegration of a heavy nucleus into
two lighter nuclei of comparable size.
Nuclear fusion occurs when two light nuclei combine to form
a single more massive nucleus, leading to the release of an
enormous amount of energy.
Radioactivity is the spontaneous and random emission of
radiation from a radioactive source like uranium and radium.
Spontaneous means that the process cannot be speeded up
or slowed down by physical means such as changes in
pressure or temperature and are unaffected by chemical
combination.
A process is random means that it is impossible to predict
which nucleus and when any particular nucleus will
disintegrate.
The rate of disintegration or activity A of a radioactive
substance is defined as the rate of disintegration of a nuclide.
The decay constant  may be defined as the fraction of the
total number of nuclei present which decay per unit time
Half-life t1/ 2 is defined as the average time taken for half the
original number of radioactive nuclei to decay
THE END
Updated Sep 2015
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