Compulsory Definitions List VI Term / Phrase Definition CLC : Physical Quantities, Units and Measurement Scalar quantities Scalar quantities are physical quantities that have magnitude only. Vector quantities Vector quantities are physical quantities that have both magnitude and direction. CA: Kinematics Speed Speed is the rate of change of distance traveled. Velocity Velocity is the rate of change of displacement. Uniform acceleration Uniform acceleration is a constant rate of change of velocity. CA: Mass, Weight and Density Mass

Mass is a measure of the amount of substance in a body. Gravitational field Gravitational field is a region in which a mass experiences a force due to gravitational attraction. Gravitational field strength Gravitational field strength is the gravitational force per unit mass. CA: Turning Effect of Forces Principle of moments The principle of moments states that 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. CA: Pressure Pressure Pressure is the force acting perpendicularly per unit area.

CA: Energy, Work and Power Principle of conservation of energy The principle of conservation of energy states that energy cannot be created or destroyed but can be converted from one form or another, and the total energy in an isolated system is constant. CLC 1: Thermal Properties of Matter Heat capacity The heat capacity of a substance is the amount of thermal energy required to raise its temperature by 1 K (or 1 co). Specific heat capacity The specific heat capacity of a substance is the amount of thermal energy required to raise the temperature off unit mass of the substance by 1 K (or 1 co).

Latent heat The latent heat of a substance is the energy it releases or absorbs during a change of Tate, without a change in its temperature. Latent heat of fusion [vaporization] The latent heat of fusion [vaporization] is the amount of thermal energy required to without a change in temperature. Specific latent heat The specific latent heat of a substance is the energy a unit mass of the substance releases or absorbs during a change of state, without a change in its temperature.

Specific latent heat of fusion [vaporization] The specific latent heat of fusion [vaporization] of a substance is the amount of thermal energy required to change a unit mass of the substance from solid state to quid state [liquid state to gaseous state], without a change in temperature. Term / Phrase CLC 2: General Wave Properties Speed (of a wave) The speed of a wave is the distance the wave travels per unit time. Frequency (of a wave) The frequency of a wave is the number of complete waves produced per second.

Wavelength The wavelength of a wave is the shortest distance between any two points of a wave in phase. Period (of a wave) The period of a wave is the time taken to produce one complete wave. Amplitude (of a wave) The amplitude of a wave is the maximum displacement of a point from its rest position. Waveforms A waveforms is an imaginary line on a wave that Joins all adjacent points that are in phase. CA: Light Normal (for reflection) The normal is a line drawn perpendicular to the reflective surface. Normal (for refraction) The normal is a line drawn perpendicular to the boundary between the two media.

Angle of incidence The angle of incidence is the angle between the incident ray and the normal. Angle of reflection The angle of reflection is the angle between the reflected ray and the normal. Angle of refraction The angle of refraction is the angle between the refracted ray and the normal. Refractive index The refractive index of a medium is the ratio of the speed of light in vacuum to the speed of light in the medium. Critical angle The critical angle is the angle of incidence in an optically denser medium for which the angle of refraction in the optically less dense medium is 900.

Total internal reflection Total internal reflection is the complete reflection of a light ray inside an optically denser medium at its boundary with an optically less dense medium. Focal length The focal length is the distance between the optical centre and the focal point. CLC 5: Sound Ultrasound audibility (above 20 kHz). CA: Static Electricity Electric field An electric field is a region in which an electric charge experiences a force. CLC 7: Current of Electricity Current Current is the rate of flow of charge. Electromotive force (e. M. F. Electromotive force is the work done by a source in driving a unit charge around a complete circuit. Potential difference (p. D. ) The potential difference across a component in a circuit as the work done to drive a unit charge through the component. Resistance The resistance of a component is the ratio of the potential difference across it to the current through it. Ohm’s Law Ohm’s Law states that the current passing through a metallic conductor is directly proportional to the potential difference across it, provided that physical conditions (such as temperature) remain constant.

CA: Practical Electricity Live The live wire is a high voltage wire that carries current to the appliance at a high voltage. It is usually at 230 V in Singapore. Neutral The neutral wire completes the circuit and carries current away from the appliance. It is usually at O V. Earth The earth wire is a low-resistance safety wire connecting the metal case of an appliance to the earth. CA: Electromagnetic Induction Faraday Lawn Faraday Law of electromagnetic induction states that the magnitude of the induced e. M. F. N a circuit is directly proportional to the rate of change of magnetic flux in the circuit. Lens’s Lens’s Law states that the direction of the induced e. M. F. , and hence the induced current in a closed circuit, is always such that its magnetic effect opposes the motion or change producing it. *Note that stating of Faraday Law and Lens’s Law are not explicitly mentioned in the syllabus (but included here since they are still useful to recall). In questions concerning electromagnetic induction, full marks may only be gained when linking