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P - 4/5 Definitions
OCR Physics A2 - Unit 4 & 5 Definitions
Question | Answer |
---|---|
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. |