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P - 4/5 Definitions

OCR Physics A2 - Unit 4 & 5 Definitions

QuestionAnswer
Capacitance The charge stored per unit potential difference. (Farads)
Farad One coulomb per unit volt.
Time Constant The time constant of a circuit containing capacitance C and a resistor of resistance R is given by t = CR.
Intensity The power per unit cross-sectional area.
Nucleon A nuclear particle, either a proton or a neutron.
Activity The rate of decay of nuclei.
Decay Constant The probability per unit time that a nucleus will decay.
Random Decay of a nucleus cannot be predicted.
Spontaneous Radioactive decay cannot be induced.
Half-Life The time taken for the activity of the source to decrease by half.
Binding Energy The minimum energy required to split a nucleus up into all of it's protons and neutrons.
Electric Field Strength Force per unit positive charge.
1 Tesla The magnetic flux density in a 1m wire carrying 1A experiences a force of 1N.
Faraday's Law The magnitude of the induced e.m.f. is equal to the rate of change of magnetic flux.
Lenz's Law The direction of the induced e.m.f. opposes the change that caused it.
Newton's First Law An object will remain at rest or continue to move with a constant velocity unless acted upon by an external force.
Newton's Second Law The rate of change of momentum of an object is directly proportional to the resultant force action on it and in the same direction.
Newton One newton is the force that gives a mass of 1kg an acceleration of 1ms⁻².
Newton's Third Law If body A exerts a force on body B, body B will exert an equal and opposite force on body A.
Principle of Conservation of Momentum In any direction, in the absence of external forces, the total momentum of a system remains constant.
Impulse Force x time for which the force acts.
Elastic Collision Momentum and Kinetic Energy are conserved.
Inelastic Collision Momentum is conserved, but Kinetic Energy is not.
Radian The angle subtended at the centre of a circle by an arc of length equal to the circle's radius.
Field The region in which a force operates.
Gravitational Field Strength Force per unit mass.
Newton's Law of Gravitation The gravitational force of attraction between two bodies is directly proportional to the product of their masses, and inversely proportional to the square of the distance between them.
Kepler's Third Law The period of a planet squared equals the mean radius of its orbit cubed.
Geostationary Satellite Travels over the equator with a period of 24 hours.
Displacement The distance an object has moved from it's equilibrium position.
Amplitude The maximum displacement.
Frequency The number of oscillations per unit time at any point.
Period The time for one complete patter of oscillation to take place at any point.
Simple Harmonic Motion An object that has an acceleration proportional to it's displacement, and is always accelerating towards the equilibrium position.
Damping Deliberately reducing the amplitude of an oscillation.
Light Damping The period of oscillation is almost unchanged, but the amplitude gradually decreases.
Resonance A large amplitude oscillation caused when an object is being driven at it's natural frequency.
Internal Energy The sum of the random microscopic kinetic and potential energies of a body.
Ideal Gas Only has internally energy in the form of random kinetic energy.
Specific Heat Capacity The energy required to raise the temperature of 1kg of mass by 1K.
Specific Latent Heat of Fusion The energy required per unit mass to change it from a solid to a liquid at constant temperature.
Specific Latent Heat of Vaporisation The energy required per unit mass to change it from a liquid to a gas at constant temperature.
Boyle's Law For a fixed mass of gas at a constant temperature, the pressure is inversely proportional to the volume.
Created by: Sparksy