Light
• Refraction is the bending of light as it goes from one medium to another.
• Laws of Refraction: (1) Incident ray, refracted ray & normal are on the same
plane. (2) Sine I/Sine R is constant.
• Refractive Index: Sine I/Sine R = 1/Sin C = Real depth/Apparent depth = c1/c2
• Critical Angle: The angle whose angle of incidence is 90 when light goes from a denser
to a rarer medium.
• Total Internal Reflection: When light travelling from a denser to a rarer medium strikes
the second medium with an angle of incidence greater than the critical angle, it is
reflected back.
Mechanics
• Acceleration is the rate of change of velocity per unit time.
Newton’s laws:
1. A body will remain in a state of rest or travelling at a constant velocity unless an external
force acts on it.
2. When an unbalanced force acts on a body, the rate of change of the body’s momentum
is directly propotional to the foce and takes place in the direction of the force. [ F ≈ (mv-
mu)/t –> F = km(v-u)/t –> F = kma –> F = ma ]
3. Every action has an equal and opposite reaction.
• Pressure is force per unit area. P = F/A -> Due to liquid: P = pgh
• Archimedes’ Principle states that when an object is partially or completely immersed in
a fluid it experiences an upthrust equal in magnitude to the weight of the fluid
displaced.
• Law of Flotation states that the weight of a floating body is equal to the weight of the
fluid it displaces.
• Boyle’s law states that at constant temperature the volume of a fixed mass of gas is
inversely proportional to to its pressure.
• Newton’s Law of Universal Gravitation states that any two point masses in the universe
attract each other with a force that is directly proportional to the product of their
masses and inversely proportional to the square of the distance between them.
• Moment = Force x Perpendicular distance
• Couple – Two parallel forces with the same magnitude acting in opposite directions.
• Torque (Moment of a couple) T = Fd
Work, Energy, Power
• Work = Force x Displacement (Joule = Newton Meter)
• Energy is the ability to do work.
• Principle of Conservation of Energy states that energy cannot be created or destroyed
but can only be converted from one form to another.
• Ek = 1/2mv2
• Ep = mgh
• Power = Work done ÷Time taken || P = w ÷ t (Watt = Joule/Second)
• Percentage Efficiency = (Output/Input) x 100
, Circular Motion
• Angular Velocity is the rate of change of angle per unit time.
• Centripetal Force: If a body is moving in a circle, the force towards the centre needed to
keep it moving is centripetal force.
• Centripetal Acceleration is acceleration a body has towards the centre of the circular
path it is moving on.
• Period of an Orbit is the time taken for a satellite to go once around the central body.
Simple Harmonic Motion and Hooke’s Law
A body is said to be moving with simple harmonic motion if:
1. It’s acceleration is directly proportional to its distance from a fixed point on its path.
2. Its acceleration is always directed towards that point.
• Hooke’s law states that when an object is bent, stretched or compressed by a
displacement ‘s’, the restoring force ‘F’ is directly proportional to the displacement –
provided the elastic limit is not exceeded.
Heat & Temperature
• Temperature is the measure of the hotness or coldness of a body.
• Thermometric properties are any physical properties that change measurably with
temperature.
• Specific Heat Capacity of a substance is the heat energy needed to change the
temperature of 1kg of the substance by 1K. (J/kg/K)
• Specific Latent Heat of a substance is the amount of heat energy needed to change the
state of 1kg of that substance without changing its temperature. (J/kg)
• Conduction is the movement of heat energy through a substance by the passing on of
molecular vibration from molecule to molecule. There is no overall motion of the
substance.
• Convection is the transfer of heat through a fluid by means of circulating currents of
fluid caused by the heat.
• Radiation is the transfer of heat energy from one place to another in the form of
electromagnetic waves.
• U Value of a structure is the amount of heat energy lost per second through 1m2 of the
structure when a temperature difference of 1K is maintained between its ends.
• Solar Constant is the average amount of the sun’s energy falling per second
perpendicularly on 1 m2 of the earth’s atmosphere. 1.35 kW/m2
Waves
• Transverse wave is a wave where the direction of the wave is perpendicular to the
direction of vibration.
• Longitudinal wave is a wave where the direction of the wave is parallel to the direction
of vibration. (e.g. Sound)
• Reflection is the bouncing of waves off an obstacle in their path.
• Refraction is the changing of direction of a wave as it enters a region where its speed is
different.
• Diffraction is the sideways spreading of waves into the region beyond a gap or around
an obstacle.
• Refraction is the bending of light as it goes from one medium to another.
• Laws of Refraction: (1) Incident ray, refracted ray & normal are on the same
plane. (2) Sine I/Sine R is constant.
• Refractive Index: Sine I/Sine R = 1/Sin C = Real depth/Apparent depth = c1/c2
• Critical Angle: The angle whose angle of incidence is 90 when light goes from a denser
to a rarer medium.
• Total Internal Reflection: When light travelling from a denser to a rarer medium strikes
the second medium with an angle of incidence greater than the critical angle, it is
reflected back.
Mechanics
• Acceleration is the rate of change of velocity per unit time.
Newton’s laws:
1. A body will remain in a state of rest or travelling at a constant velocity unless an external
force acts on it.
2. When an unbalanced force acts on a body, the rate of change of the body’s momentum
is directly propotional to the foce and takes place in the direction of the force. [ F ≈ (mv-
mu)/t –> F = km(v-u)/t –> F = kma –> F = ma ]
3. Every action has an equal and opposite reaction.
• Pressure is force per unit area. P = F/A -> Due to liquid: P = pgh
• Archimedes’ Principle states that when an object is partially or completely immersed in
a fluid it experiences an upthrust equal in magnitude to the weight of the fluid
displaced.
• Law of Flotation states that the weight of a floating body is equal to the weight of the
fluid it displaces.
• Boyle’s law states that at constant temperature the volume of a fixed mass of gas is
inversely proportional to to its pressure.
• Newton’s Law of Universal Gravitation states that any two point masses in the universe
attract each other with a force that is directly proportional to the product of their
masses and inversely proportional to the square of the distance between them.
• Moment = Force x Perpendicular distance
• Couple – Two parallel forces with the same magnitude acting in opposite directions.
• Torque (Moment of a couple) T = Fd
Work, Energy, Power
• Work = Force x Displacement (Joule = Newton Meter)
• Energy is the ability to do work.
• Principle of Conservation of Energy states that energy cannot be created or destroyed
but can only be converted from one form to another.
• Ek = 1/2mv2
• Ep = mgh
• Power = Work done ÷Time taken || P = w ÷ t (Watt = Joule/Second)
• Percentage Efficiency = (Output/Input) x 100
, Circular Motion
• Angular Velocity is the rate of change of angle per unit time.
• Centripetal Force: If a body is moving in a circle, the force towards the centre needed to
keep it moving is centripetal force.
• Centripetal Acceleration is acceleration a body has towards the centre of the circular
path it is moving on.
• Period of an Orbit is the time taken for a satellite to go once around the central body.
Simple Harmonic Motion and Hooke’s Law
A body is said to be moving with simple harmonic motion if:
1. It’s acceleration is directly proportional to its distance from a fixed point on its path.
2. Its acceleration is always directed towards that point.
• Hooke’s law states that when an object is bent, stretched or compressed by a
displacement ‘s’, the restoring force ‘F’ is directly proportional to the displacement –
provided the elastic limit is not exceeded.
Heat & Temperature
• Temperature is the measure of the hotness or coldness of a body.
• Thermometric properties are any physical properties that change measurably with
temperature.
• Specific Heat Capacity of a substance is the heat energy needed to change the
temperature of 1kg of the substance by 1K. (J/kg/K)
• Specific Latent Heat of a substance is the amount of heat energy needed to change the
state of 1kg of that substance without changing its temperature. (J/kg)
• Conduction is the movement of heat energy through a substance by the passing on of
molecular vibration from molecule to molecule. There is no overall motion of the
substance.
• Convection is the transfer of heat through a fluid by means of circulating currents of
fluid caused by the heat.
• Radiation is the transfer of heat energy from one place to another in the form of
electromagnetic waves.
• U Value of a structure is the amount of heat energy lost per second through 1m2 of the
structure when a temperature difference of 1K is maintained between its ends.
• Solar Constant is the average amount of the sun’s energy falling per second
perpendicularly on 1 m2 of the earth’s atmosphere. 1.35 kW/m2
Waves
• Transverse wave is a wave where the direction of the wave is perpendicular to the
direction of vibration.
• Longitudinal wave is a wave where the direction of the wave is parallel to the direction
of vibration. (e.g. Sound)
• Reflection is the bouncing of waves off an obstacle in their path.
• Refraction is the changing of direction of a wave as it enters a region where its speed is
different.
• Diffraction is the sideways spreading of waves into the region beyond a gap or around
an obstacle.
