O Level Physics Statements and Definitions

01 Physical Quantities, Units and Measurement: scalar quantity

physical quantities that have only magnitude

01 Physical Quantities, Units and Measurement: vector quantity

physical quantities that have both magnitude and direction

02 Kinematics: speed

distance travelled per unit time

02 Kinematics: velocity

rate of change of displacement

02 Kinematics: acceleration

rate of change of velocity

02 Kinematics: uniform acceleration

constant rate of change of velocity

02 Kinematics: acceleration of free fall for a body near to earth

constant and is approximately 10 m/s²

03 Dynamics: mass

a measure of the amount of matter in a body

03 Dynamics: gravitational field

region in which a mass experiences a force due to gravitational attraction

03 Dynamics: weight

gravitational force acting on an object that has mass

03 Dynamics: gravitational field strength, g

gravitational force per unit mass placed at that point

04 Turning Effect of Forces: moment of a force about a pivot

product of the force and the perpendicular distance from the pivot to the line of action of the force

04 Turning Effect of Forces: principle of moments for a body in equilibrium

When a body is in equilibrium, the sum of clockwise moments about a pivot is equal to the sum of anticlockwise moments about the same pivot.

05 Pressure: pressure

force acting per unit area

05 Pressure: density

mass per unit volume

06 Energy: principle of the conservation of energy

Energy cannot be created or destroyed. Energy can be transferred from one store to another. The total energy of an isolated system is constant.

06 Energy: work done by a constant force

the product of the force and the distance moved by the object in the direction of the force

06 Energy: power

work done or energy transferred per unit time

09 Thermal Properties of Matter: heat capacity of an object

the change in its internal energy (the amount of heat released or absorbed by an object) per unit change in its temperature

09 Thermal Properties of Matter: specific heat capacity of an object

the change in its internal energy (the amount of heat released or absorbed by an object) per unit mass for each unit change in its temperature

09 Thermal Properties of Matter: latent heat

the energy transferred to change the state of a substance (between the solid and liquid states: latent heat of fusion; between the liquid and gaseous states: latent heat of vaporisation), at constant temperature

09 Thermal Properties of Matter: specific latent heat

the energy transferred per unit mass to change the state of a substance (between the solid and liquid states: specific latent heat of fusion; between the liquid and gaseous states: specific latent heat of vaporisation), at constant temperature

10 General Properties of Waves: speed of a wave

distance travelled by the wave per unit time

10 General Properties of Waves: frequency of a wave

number of oscillations each point on a wave completes per unit time

10 General Properties of Waves: wavelength

shortest distance between two successive points with the same phase (e.g. two successive crests or troughs)

10 General Properties of Waves: period of a wave

time taken by each point on the wave to complete one oscillation

10 General Properties of Waves: amplitude of a wave

maximum magnitude of displacement of a point on the wave from its equilibrium position

11 Electromagnetic Spectrum: electromagnetic waves

transverse waves that travel with the same speed (3.0 × 10⁸ m/s) in vacuum

11 Electromagnetic Spectrum: typical uses of radio waves

radio and television communication, astronomy and RFID tags

11 Electromagnetic Spectrum: typical uses of microwaves

mobile (cell) phones, microwave oven and satellite television

11 Electromagnetic Spectrum: typical uses of infrared radiation

infrared remote controllers, intruder alarms and thermal imaging

11 Electromagnetic Spectrum: typical uses of visible light

photography, optical fibres in medicine and telecommunications

11 Electromagnetic Spectrum: typical uses of ultraviolet radiation

sunbeds, bank note authentication and disinfecting water

11 Electromagnetic Spectrum: typical uses of X-rays

medical radiology, security screening and industrial defect detection

11 Electromagnetic Spectrum: typical uses of gamma rays

sterilising food, detection of cancer and its treatment

12 Light: law of reflection

the angle of incidence is equal to the angle of reflection

12 Light: refractive index of a medium

ratio of the speed of light in a vacuum to the speed of light in that medium

12 Light: focal length of a thin converging lens

distance between the optical centre and a focal point

13 Static Electricity: types of charge, unit of charge

there are positive and negative charges and charge is measured in coulombs

13 Static Electricity: force by unlike charges on each other

attractive electric force

13 Static Electricity: force by like charges on each other

repulsive electric force

14 Current of Electricity: definition and unit of current

rate of flow of charge (unit: ampere)

14 Current of Electricity: electromotive force (e.m.f.) of an electrical source

work done per unit charge by the electrical source in driving charges around a complete circuit (unit: volt)

14 Current of Electricity: potential difference (p.d.) across a component in a circuit

work done per unit charge in driving charges through the component (unit: volt)

14 Current of Electricity: resistance

p.d. / current

15 D.C. Circuits: ___ through every point in a series circuit is the same

current

15 D.C. Circuits: sum of the potential differences in a series circuit

equal to the potential difference across the whole circuit

15 D.C. Circuits: sum of the currents in the separate branches of a parallel circuit

equal to the current from the source

15 D.C. Circuits: ___ across the separate branches of a parallel circuit is the same

potential difference

16 Practical Electricity: hazards of using electricity - damaged insulation

electric shocks/electrocution when touched

16 Practical Electricity: hazards of using electricity - overheating of cables

overheating, fire

16 Practical Electricity: hazards of using electricity - damp conditions

electric shocks/electrocution if there is damaged insulation

16 Practical Electricity: live wire

red/brown high-voltage wire that carries current from the source to the appliance

16 Practical Electricity: neutral wire

blue zero-voltage wire that completes the path for current to flow from the appliance to the source

16 Practical Electricity: earth wire

yellow and green low-resistance safety wire that is needed to earth (neutralise any excess charge on) the metal cases of appliances (by allowing electrons to flow between the metal case and the ground)

17 Magnetism: state the properties of magnets

like poles repel, unlike poles attract, rest in the north-south direction, have two poles, attract magnetic materials

20 Radioactivity: nuclear fusion

process in which two light atomic nuclei combine to form a heavier atomic nuclei and releases a huge amount of energy

20 Radioactivity: nuclear fission

process in which the nucleus of an atom splits (usually into two parts) and releases a huge amounts of energy