O Level Pure Physic- Physics Definition List

Physics Definition

Kinetic Model Of Matter:

Transfer of Thermal Energy:

Brownian Motion is the movement of smoke particles in a random and continuous motion in all direction.

Conduction is the process by which heat is transferred through a medium by the collisions of one particle to another.

Conclusion: Provide Evidence that air molecules are always in continuous and random motion.

Convection is the process by which heat is transmitted from one place to another by the movement of heated particles in a gas or liquid.

Specific heat capacity(c): Is the amount of heat required to raise the temperature of 1kg of the object by 1oc

Q = mcθ Melting is the process in which a substance changes from a solid state to a liquid state without a change in temperature.

Temperature: It is the measure of the degree of hotness of a body. Heat refers to the amount of thermal energy that is contained in a body. Lower-fixed point aka Ice Point: Temperature of pure melting ice at standard atmospheric pressure. Upper-fixed point aka steam point: Temperature of steam from boiling water at standard atmospheric pressure.

Radiation is the process of heat transfer through the emission or absorption of electromagnetic waves Thermal Properties Matter: Energy = power x time

Boiling is the process in which a substance changes from a liquid state to a gaseous state without a change in temperature.

of

Latent heat of fusion (lf) of a substance is the quantity of heat needed to change a unit mass of the substance from solid to liquid without a change in temperature.

Internal Energy is the sum of kinetic energy and potential energy of all the particles. Heat Capacity(C) is the amount of heat required to raise the temperature of the object by 1oc.

C=

Q = ml

Q

θ

-1-

f

Latent heat of vaporization (lv): of a substance is the quantity of heat needed to change a unit mass of the substance from liquid to gas without a change in temperature.

Q = ml

v

Light: Law 1: The angle of incidence is = to the angle of reflection. Law2: The incident ray, reflected ray and normal lies at the point of incidence all lie on the same plane. Refraction: The bending of light when it passes from one transparent medium to another. Law1: The incident ray, refracted ray and normal the point of incidence all lie on the same plane Law2: For 2 given media,

Physics Definition

n=

sin i (Less sin r

dense

to

denser medium)

n=

sin r (Denser to less sin i

dense medium) (n= refractive index or optical density) Refractive index of medium:

c n= v C= speed of light 3x108 V= velocity of light

Thin converging lenses:

1 sin c = n Conditions for TIR: 1. Light must travel from an optically denser medium into optically less dense medium

Wavelength ( λ ): distance between 2 identical points on successive waves.

Focal length F is the distance between the optical center of the lens to the focal point

Frequency (f): no of complete wave in one second.

Linear magnification (m) is the ratio of the image height (hi) to the object height (ho).

m=

Total internal reflection: Critical angle(c): is the angle of incidence for which the angle of refraction in the optically dense medium is 90o.

Amplitude (a): Maximum displacement of wave from rest position.

2. Angle of incidence (i) must be greater than the critical angle(c).

Period (T): time taken to generate one complete wave.

hi ho

T=

(Or the image distance (v) from the lens to the object distance (u) from the lens)

m =

1 f

Speed of wave: Distance moved by any point on the wave in one second.

v u

Hence,

v= fλ

Transverse wave: are waves in which the direction of vibration is perpendicular to the direction of wave motion.

General Wave Properties: Wave: Phenomenon which energy is transferred through vibrations.

Longitudinal waves: are waves in which the direction of vibration of the wave particles is parallel to the direction of wave motion. Wave front: imaginary line on a wave that joins all points which have the same phase of vibration. Sound: Compressions: region where air particles is slightly higher than normal atmospheric pressure. Rarefaction: region where air particles is slightly lower than normal atmospheric pressure. Echo: reflected sound wave from large and hard surface. Loudness: dependent on amplitude. Pitch: dependent on frequency of the wave

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Physics Definition

Ultrasound are sound that are above the upper hearing limit of the human ear. Kinematics:

a=

Scalar:
units
magnitude
no direction

v−u t

Terminal Velocity: When an object falls at a constant maximum velocity, with an acceleration of 0m/s2, it is known as terminal velocity.

Vector:
direction
units
no magnitude Distance (d) total length covered by a moving object. Displacement(s) distance measured specific direction.

the in a

Speed is the rate of change of distance with time.

Area under graph equals to distance travelled. In general, average speed is always area under graph divide by time. Average speed=

The Downward force is equal to the upward force, hence no net force.

area.under.graph t

Distance-time graph: Gradient: object.

speed

When acceleration constant in graph,

of

If it is a straight line, it is travelling at a constant speed.

d Speed = t Velocity (v) is the rate of change of displacement with time.

Velocity =

Gradient gives the acceleration. Positive gradient: acceleration. Negative gradient: Deceleration or retardation. Zero gradient: (i) object at rest (ii) moving at constant speed

Acceleration (a) is the rate of change of velocity with time.

Velocity-time/ time graph:

average.speed =

1 (v + u ) 2

v= Final velocity u=Initial velocity t= time taken change

speed-

s t -3-

is

for

Dynamics: Newton 1st Law: When there is no net force acting on a body, the body will remain at rest and a body in motion will continue its motion at constant velocity. Newton 2nd Law: Net force action on a body is directly proportional to the product of the object’s mass and the acceleration it produces. Resultant/net force:

FR=ma Resultant force produces acceleration
constant net force=constant acceleration.
doubling net force will double acceleration produce
Doubling mass requires a force twice as large to achieve the same acceleration.

Physics Definition

Newton 3rd Law: For every action, there is an equal and opposite reaction, and they act on different bodies.

Moment of force is the product of the force, and the perpendicular distance from the line of action of the force to the pivot.

Friction is a force opposes motion.

Principle of moments states that when a body is in equilibrium, the total clockwise moments about the pivot = to the total anticlockwise moment about the same pivot.

Mass, Weight & Density: Mass is a measure of the amount of matter in an object. SI unit: kilogram (kg) Weight is due to the pull of gravity (or, gravitational force of attraction) upon a mass. Gravitational field strength (g) is define as the gravitational force acting per unit mass of a body. Density is the mass per unit volume of a substance.

Work done by a force is the product of force applied and the distance moved in the direction of the force.

Turning Effect of Forces

Inertia is the reluctance of a body to change its state of rest or motion. Or It is the tendency of a body to remain at rest, or continue moving at a constant speed. that

Work, Energy & Power:

M ρ= V

W .D = F
x
d Energy is defined as the capacity to do work.

Moment = Fx ⊥ d

K.E is the energy possesses due to its motion.

K .E . =

1 2 mv 2

G.P.E is the energy a body possesses due to its position from the surface of the earth.

Centre of gravity of an object is the point where the whole weight of the object seems to act on.

G.P.E. = mgh The principle of the conservation of energy states that Energy can neither be created nor destroyed in any process. It can be converted from one form to another or transferred from one body to another but the total amount remains constant.

Stability is a measure of a body’s ability to regain its original position

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Power is the rate of work done or energy converted.

P=

W .D E or P = t t

Pressure is the force acting per unit area on a body.

P=

F A

Pressure due to liquid:

P = hρ g Atmospheric pressure is the weight exerted by the atmosphere. Output force in a hydraulic system=

A  FB = FA  B   AA  A barometer is an instrument used for measuring atmospheric pressure.

Physics Definition

Static Electricity Electric Field is the region where an electric charge experiences an electric force. Magnetism Magnetic Field is the region around a magnet in which a magnetic force can be detected by a magnetic material. Electricity Charge is measured in coulombs (C) Charge of one electron is -1.6x1018 . Current is the rate of flow of charge that flows through any particular point.

I=

Q t

E.m.f is defined as the work done by a force in driving a unit charge around a complete circuit.

W ε= Q

Potential Divider divides voltage proportionally into 2 voltages.

Voltage is the work done to drive a unit charge through the component.

V=

W Q

V2 IR2 = VT I ( R1 + R2 )

Resistance is the ratio of the potential difference across the component to the current flowing though it.

Earth Wire is used for safety reasons. Connected to metal casing of an appliance and direct excess currents due to the ground when there is a leakage or a short circuit.

RI = V Power of an electrical component is the product of the current flowing through it and the potential difference across it.

Fuse melts when excess current flows through it breaking the circuit to prevent current from flowing to prevent user from electrocution and also prevent damage to appliance.

P = IV Ohm’s Law states that the current passing through a conductor is directly proportional to the potential difference between its ends provided that the physical conditions and temperature remains constant.

Electromagnetism/ Electromagnetic Induction Permanent Magnet: provide strong magnetic field. Curved in to provide radial field.

Diode only allows current to flow in one direction Rectification is the process of converting alternating current to a direct current usually through the use of a diode.

Carbon Brushes: Provide electrical contact between circuit and coil

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Soft Iron Core: to concentrate magnetic field lines around the coil to exert a greater force on the coil. (D.C motor)Split ring commutator: Reverses the direction of current flowing into the coil for every half a turn to ensure the coil rotates in one direction. (A.C motor)Slip ring: Reverse direction of induced current flowing in the coil for every half a rotation. Why transformer need A.C? It is to provide a constantly changing magnetic field for electromagnetic induction. Hence a constantly changing current is required.