Definition List

8/3/2019 Definition List

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Chapter 1: Introduction to Physics

Physical quantities QUANTITIES that are measurable

Base quantities PHYSICAL QUANTITIES that cannot be defined in terms of

other physical quantities but has its own definition

Derived quantities PHYSICAL QUANTITIES that are derived from base

quantities by multiplication or division or both

Scalar quantity QUANTITY which has only magnitude or size (time,

temperature, mass, volume, distance, density, power)

Vector quantity QUANTITY which has both magnitude or size and direction

(force, velocity, displacement, acceleration, momentum)

Systematic errors CUMULATIVE ERRORS that can be corrected, if the

errors are known. (zero error, incorrect calibration ofmeasuring instrument)

Random errors ERRORS that arise from unknown and unpredictable

variations in condition, and will produce a different error

Zero error ERROR that arises when the measuring instrument does not

start from exactly zero

Parallax error ERROR in reading an instrument because the observers eyes

and the pointer are not in a line perpendicular to the plane of

scale

Consistency ABILITY to register the same reading when a measurement is

repeated (improve eliminates parallax error, greater care,

not detective instrument)

Accuracy DEGREE to which a measurement represents the actual

value (improve repeat readings, avoid parallax/zero error,

high accuracy instrument)

Sensitivity ABILITY to detect quickly a small change in the value of a

measurement (thermometer thin wall bulb, narrowcapillary)


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Chapter 2: Forces and Motion

Distance how far a body travels during motion

Displacement CHANGE IN POSITION of an object from its initial position in a

specified direction

Speed RATE OF CHANGE of distance

Velocity RATE OF CHANGE of displacement

Mass AMOUNT of matter in the object

Acceleration RATE OF CHANGE of velocity

Inertia PROPERTY of matter that causes it to resist any change in its

motion or state of rest

Momentum PRODUCT of mass and velocity

Force pulling or a pushing ACTION on an object

Impulsive force LARGE FORCE which acts over a very short time

interval/RATE OF CHANGE in momentum

Gravity FORCE originated from centre of the Earth that pulls allobjects towards the ground

Free fall FALLING of an object without encountering any resistance from a

height towards the earth with an acceleration due to gravity

Forces in equilibrium An object is said to be in a state of equilibrium when

forces act upon an object and it remains stationary or moves

at a constant velocity

Resultant force SINGLE FORCE which combines two or more forces

which act on an object

WorkWork is done when a force causes an object to move in the direction of the

force.

Energy CAPACITY of a system to do work

Gravitational PE ENERGY STORED in the object because of its height above

the earth surface

Elastic PE ENERGY STORED in the object as a result of stretching or

compressing it

Kinetic energy ENERGY possessed by a moving object


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Power RATE at which work is done or energy is changed and

transferred

Efficiency ABILITY of an electrical appliance to transform energy from

one form to another without producing useless energy or

wastage

Elasticity PROPERTY of an object that enables it to return to its original

shape and dimensions after an applied force is removed

Spring constant FORCE needed to extend a spring per unit length

Elastic limit MAXIMUM STRETCHING FORCE which can be applied to an

elastic material before it ceases to be elastic

PRINCIPLE

Hookes Law

the force, F applied to a spring is directly proportional to the springs extension

or compression, x, provided the elastic limit is not exceeded.

Principle of conservation of energy

total energy in an isolated system is neither increased nor decreased by any

transformation. Energy cannot be created nor destroyed, but it can be

transformed from one kind to another, and the total amount stays the same.

Principle of conservation of momentum

in any collision or interaction between two or more objects in an isolated system,

the total momentum of the system will remain constant; that is, the total initial

momentum will equal the total final momentum.

Newtons first law of motion

a body will either remain at rest or continue with constant velocity unless it is

acted on by an external unbalanced force.

Newtons second law of motion

the acceleration a body experiences is directly proportional to the net force

acting on it, and inversely proportional to its mass. F =ma

Newtons third law of motion

to every action there is an equal but opposite reaction.


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Chapter 3: Forces and Pressure

Pressure FORCE acting normally on a unit surface area

Gas pressure FORCE per unit area exerted by the gas particles as they

collide with the walls of their container (due to the rate of change of

momentum)

Buoyant force NET FORCE acting upwards due to the difference between

the forces acting on the upper surface and the lower surface

PRINCIPLE

Law of Flotation

the weight of an object floating on the surface of a liquid is equal to the weight ofwater displaced by the object. (weight of object = weight of water displaced)

Archimedes principle

the buoyant force on a body immersed in a fluid is equal to the weight of the

fluid

displaced by that object (buoyant force = weight of water displaced)

Pascals Principle

a pressure applied to a confined fluid is transmitted uniformly in all directions

throughout the fluid.

Bernoullis principle

the pressure of a moving fluid decreases as the speed of the fluid increases, and

the

converse is also true.


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Chapter 4: Heat

Temperature DEGREE of hotness of an object

Thermometric property PHYSICAL PROPERTY of a substance which is

sensitive to and varies linearly with the temperature

change

Thermal equilibrium A STATE when heat transfer between the two objects

are equal and the net rate of heat transfer between the

two objects are zero

Heat capacity HEAT ENERGY required to raise its temperature

by 1C or 1 K

Specific heat capacity HEAT ENERGY required to produce 1C or 1 K rise intemperature in a mass of 1 kg.

Latent heat HEAT ABSORBED OR RELEASED when a substance

changes its state without a change in temperature is

calledthe latent heat of the substance

Specific latent heat of fusionHEAT ENERGY required to change 1 kg of a

substance from solid state to liquid state, without a

change in temperature

of vapourisation HEAT ENERGY required to change 1 kg of a substancefrom liquid state to gaseous state, without a change in

temperature at its boiling point

PRINCIPLE

Boyles Law

the pressure of a fixed mass of gas is inversely proportional to its volume

provided the

temperature of the gas is kept constant(PV = k)


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Pressure Law

the pressure of a fixed mass of gas is directly proportional to its absolute

temperature (in

Kelvin), provided the volume of the gas is kept constant (P/T = k)

Charles Law

the volume of a fixed mass of gas is directly proportional to its absolute

temperature (in

Kelvin), provided the pressure of the gas is kept constant

Chapter 5: Light

Refraction PHENOMENON where the direction of light is changed when it

crosses the boundary between two materials of different optical

densities as a result of a change in the velocity of light.

Apparent depth,d DISTANCE of the image from the surface of water (or

the boundary between the two mediums involved)

Real depth,D DISTANCE of the object from the surface of the water (or the

boundary between the two mediums involved)

Total internal reflection TOTAL REFLECTION of a beam of light at the

boundary of two mediums, when the angle of incidence

in the optically denser medium exceeds a specific

critical angle

Critical angle GREATEST ANGLE OF INCIDENCE in the optically denser

medium for which the angle of refraction, r = 90

Power of lens MEASURE OF ITS ABILITY to converge or diverge an

incident beam of light


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PRINCIPLE

Laws of Reflection

-the angle of incidence, i, is equal to the angle of reflection, r (i = r)

-the incident ray, normal and reflected ray will all lie in the same plane

Law of Refraction

-The incident ray and the refracted ray are on the opposite sides of the normal at

the point of incidence, all three lie

in the same plane

-Obey Snells law

Snells Law

The value of sin i/sin r is a constant

IMAGE CHARACTERISTICS

Virtual an image which cannot be projected (focused) onto a

screen

Real an image which can be projected (focused) onto a screen

Laterally inverted an image which left and right are interchanged

Upright an image which in vertical position

Diminished image formed is smaller than the object


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Magnified image formed is larger than the objec

Chapter 1 Waves

Waves

A TYPE OF DISTURBANCE produced by an oscillating or vibrating motion in whicha point or body moves back

and forth along a line about a fixed central point produces waves.

Wavefront

LINE OR PLANE on which the vibrations of every points are in phase and are at

the same distance from the source

of the wave.

In phase = same direction, same displacement

Transverse Wave

WAVE in which the vibration of particles in the medium is perpendicular to the

direction of propagation of the wave

(water waves, light waves, electromagnetic waves)

Longitudinal Wave

WAVE in which the vibration of particles in the medium is parallel to the direction

of propagation of the wave


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(sound waves, ultrasound)

Amplitude

MAXIMUM DISPLACEMENT form its equilibrium position

MEASURE of height of the wave crest or depth of the wave trough.

Period

TIME TAKEN to complete an oscillation, from one extreme point to the other and

back to the same position.

Frequency

NUMBER OF COMPLETE OSCILLATIONS made by a vibrating system in one second

Wavelength,

DISTANCE between successive points of the same phase in a wave

Damping

DECREASE in the amplitude of an oscillating system is called damping

(Internal damping: extension and compression of molecules

External damping: frictional force/ air resistance)

Resonance

Resonance occurs when a system is made to oscillate at a frequency equivalent

to its natural frequency by an

external force. The resonating system oscillates at its maximum amplitude.

Natural frequency

FUNDAMENTAL FREQUENCY of which an object vibrates. It is the frequency of a

system which oscillates freely

without external force

Reflection of wave

Reflection of wave occurs when a wave strike an obstacle

direction ; f = ; a = ; =

Refraction of wave

Refraction of wave occurs when a wave travel from one medium to another

f = ; v

;

; direction


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Diffraction of waves

PHENOMENON in which waves spread out as they passed through an aperture or

round a small circle

f = ; = ; speed = ; v ; direction

Interference of waves

SUPERPOSITION of two waves originating from two coherent sources

coherent = same frequency, amplitude and in phase

Constructive interference

Constructive interference occurs when the both crests or both troughs of both

waves coincide to produce a wave

with crests and troughs of maximum amplitude

Destructive interference

Destructive interference occurs when the crest of one wave coincides with the

trough of the other wave, thus

cancelling each other with the result that the resultant amplitude is zero.

Antinode

POINT where constructive interference occurs.

Node

POINT where destructive interference occurs

Electromagnetic waves

PROPAGATING WAVES in space with electric and magnetic components. These

components oscillate at right

angles to each other and to the direction of propagation of wave.

Monochromatic light

LIGHT with only one wavelength and colour

PRINCIPLE

Principle of superposition

Principle of superposition states that at any instant, the wave displacement of

the combined motion of any number of


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interacting waves at a point is the sum of the displacements of all the

components waves at that point.

Chapter 2 Electricity

Charge, Q

WORK DONE to move a unit of voltage in a circuit

Current, I

RATE of flow of charge

Potential difference, V

WORK DONE in moving one coulomb of charge from one point to another in an

electric field

Electric field

A FIELD in which electric charge experiences an electric force

A FIELD in which electric force acts in a particle with electric charge

Circuit

CLOSED LOOP through which charge can continuously flow

Resistance, R

RATIO of the potential difference across the conductor to the current flowing

through it

MEASURE of the ability of the conductor to resist the flow of an electric current

through it

Superconductor


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CONDUCTOR in which its resistance will suddenly become zero when it is cooled

below a certain temperature

called the critical temperature

Electromotive force (e.m.f.)

TOTAL ENERGY supplied by a cell to move a unit of electrical charge from one

terminal to the other through the

cell and the external circuit

Power rating

RATE at which it consumes electrical energy.

PRINCIPLE

Ohms Law

Ohms law states that the electric current,I flowing through a conductor is

directly proportional to the potential

difference across the ends of conductor, if temperature and other physical

conditions remain constant. That is, v is

directly proportional to r


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Chapter 4 Electronics

Thermoionic emission

EMISSION of electrons from hot metal surface

Work function MINIMUM ENERGY required to eject electrons from surface

Cathode ray

fast moving ELECTRONS travel in a straight line in vacuum

Cathode ray oscilloscope

measuring and testing INSTRUMENT used in study of electricity and electronics

Conductor

MATERIAL which allows current to flow through them

Semiconductor

MATERIAL whose resistance is between good conductor and insulator

Insulator

MATERIAL which does not conduct electric current

Junction voltage

POTENTIAL DIFFERENCE acting from n-type to p-type material of a diode across

the depletion layer


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Rectification

CONVERSION of a.c. to d.c. by diode

Smoothing

PROCESS where output is smoothed by connecting a capacitor across load that

acts as a reservoir and maintains

potential difference across load

Logic gates

ELECTRONIC SWITCHES with one or more inputs and one output.

Chapter 5 Radioactivity

Atom

An atom consists of a nucleus which is made up of protons and neutrons, with

electrons orbiting the nucleus.

Nuclide

TYPE of nucleus with particular proton number and nucleon number

Proton number

NUMBER of protons in the nucleus of an atom

Nucleon number

NUMBER of protons and neutrons in an atom

Isotopes

ATOMS of an element which have the same proton number but different nucleon

number(similar chemical

properties but differs in physical properties)

Radioactivity

SPONTANEOUS DISINTEGRATION of unstable nucleus into a more stable nucleus

with the emission of

energetic particles or protons


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Radioactive decay

PROCESS where an unstable nucleus becomes a more stable nucleus by emitting

radiations

Radioisotope

ISOTOPE that has unstable nucleus that tends to undergo radioactive decay

Half life

TIME TAKEN for the activity of atoms to fall to half its original value

TIME TAKEN for half the atoms in a given sample to decay

Nuclear fission

PROCESS involving the splitting of a heavy nucleus into two nuclei of roughly

equal mass and shooting out several

neutrons at the same time.

Nuclear fusion

PROCESS involving the fusion of two or more small and light nuclei come

together to form a heavier nucleus.

PRINCIPLE

Einsteins Principle of Mass-Energy Conservation

The change of energy is linked to the change of mass by the equation, E=mc2

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