definitions

• Scalar quantities

  Physical quantities that have only magnitude
• Vector quantities

  Physical quantities that have both magnitude and direction
• Speed

  The distance travelled per unit time
• Velocity

  The rate of change in displacement
• Uniform acceleration

  It is when the change in the velocity of an object for every unit of time is the same
• Mass

  It is the measure of the amount of matter in a body
• Gravitational field

  It is a region in which a mass experiences a force due to gravitational attraction
• Gravitational field strength

  It is gravitational force per unit mass placed at that point
• Pressure

  It is the force acting per unit area
• Heat capacity

  It is the change of its internal energy per unit change in its temperature
• Specific heat capacity

  It is the change of its internal energy per unit mass for each unit change in its temperature
• Latent heat

  It is the energy released or absorbed to change the state of substance, at constant temperature
• Specific latent heat of fusion

  It is the amount of energy transferred per unit mass of a substance to change between the solid and liquid states, at constant temperature
• Transverse wave

  It has a direction of vibration that is perpendicular to the direction of wave travel
• Longitudinal wave

  It has direction of vibration that is parallel to the direction of wave travel
• Frequency

  It is the number of oscillations each point completes per second
• Wavelength

  It is the shortest distance between 2 successive crests or troughs
• Period

  It is the time taken by each point on the wave to complete 1 oscillation
• Amplitude

  It is the wave's maximum magnitude of displacement from its rest position
• Refractive index

  The ratio of speed in a vacuum to the speed of light in the medium
• Critical angle

  It is the angle of incidence in an optically denser medium for which the angle of refraction in the less dense medium is 90 °
• Total internal reflection

  It is the complete reflection of a light ray in an optically denser medium at the boundary with an optically less dense medium
• Focal length

  The distance between the optical centre and the principal focus point
• Current

  It is the rate of flow of charge and is measured in amperes
• Electromotive force

  It is the work done per unit charge by the source in driving charges around a complete circuit and that it is measured in volts
• Potential difference

  It is the work done per unit charge in driving charges through the component and is measured in volts
• Resistance

  It is the ratio of the potential difference across it to the current flowing through it
• Earth wire

  It is yellow and green. It is a safety wire that is needed to earth appliances with a metal case
• Neutral wire

  It is blue and is kept at 0V. It completes the path for current to flow through appliances in the electrical circuit
• Live wire

  It is brown and carries both the high voltage and the current
• Nuclear fusion

  It is a process in which 2 light atomic nuclei combine to form 1 heavier atomic nucleus and releases a huge amount of energy
• Nuclear fission

  It is a process in which the nucleus of an atom splits (usually into 2 parts) and releases a huge amount of energy