# Physics Definitions

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• Created by: Alibunn
• Created on: 04-03-14 10:16
Electric Charge
An electric charge occurs when there are fewer or more electrons than protons.
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Current
Is caused by the movement of electrons
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A.C
Alternating Current - electrons constantly change direction of motion
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D.C
Direct Current - Electrons move in one direction
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Potential Difference
Number of Joules of energy given to each coulomb of charge passing through the cell
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Series Circuit
Has only one path round it
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Parallel Circuit
Has more than one path round the circuit
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Thermistor
Resistor whose resistance changes with changes in temperature
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LDR
Resistor whose resistance changes with changes in light level
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Power
Number of Joules of energy used per second
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Specific Heat Capacity
The numebr of Joules of energy required to raise the temperature of 1kg of a material by 1 degree Celsius
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Temperature
A measure of the mean kinetic energy of the particles
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Heat
Energy of a substance
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Conservation of Energy
Energy cannot be created or destroyed only transormed from one type to another.
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Pressure
Force per unit area
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Absolute zero
Temperature of 0K or -273 degrees Celsius - particles have no kinetic energy
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Average speed
distance divided by time
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Average velocity
displacement divided by time
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Vector
A quantity that needs magnitude and direction to be described correctly
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Scalar
A quantity that only needs magnitude to be described correctly
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Distance
The total length of the path taken
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Displacement
The length between start and finish points
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Acceleration
Change in velocity per second
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Balanced Force
Equal Forces in opposite directions
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Friction
Two surfaces rubbing together
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Streamlining
Changing the shape of an object to reduce frictional forces
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Work
Energy used to move an object over a distance
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Weight
Force downwards caused by the gravitational field strength
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Mass
A measure of all the particles that make an object up
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Gravitational Field Strength
Force per unit mass
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Newtons 3rd Law
For every action force there is an equal and opposite reaction force
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Terminal Velocity
Weight down = Air resistance upwards resulting in a constant velocity
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Latent Heat of Fusions
Number of Joules of heat energy required to change 1kg of a solid into 1kg of a liquid with no temperature change
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Latent Heat of Vapourisation
Number of Joules of heat energy required to change 1kg of a liquid into 1kg of a gas with no change in temperature
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Light Year
The distance that light can travel in a year
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Observable Universe
Furthest point that we can see or detect
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Longitudinal Wave
A wave that vibrates along the direction of travel
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Transverse Wave
A wave that vibrates at 90 degrees to the direction of travel
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Wavelength
Distance from a point on one wave to the same point on the next
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Frequency
Number of waves per second
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Amplitude
Distance from the centre of a wave to the crest or trough
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Period of a wave
The time it takes one wave to pass a point
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Diffraction
Bending of waves round an obstacle
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Refraction
Chane in speed of light as it changes material
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Normal
Imaginary line at 90 degrees to a surface
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Ionisation
When an atom gains or loses an electron to become charged
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Absorbed Dose
Energy absorbed per unit mass
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Equivalent Dose
Is a way to take into account the type of radiation and the absorbed dose
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Activity
Number of decays per second
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Half Life
Length of time it takes th activity of a source to reduce to a half of its original value.
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Fission
A large mass nucleus splits into two or more nuclei of smaller mass and neutrons are released
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Fusion
Two nuclei of smaller mass combine to form a nucleus of larger mass
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## Other cards in this set

### Card 2

#### Front

Is caused by the movement of electrons

Current

### Card 3

#### Front

Alternating Current - electrons constantly change direction of motion

### Card 4

#### Front

Direct Current - Electrons move in one direction

### Card 5

#### Front

Number of Joules of energy given to each coulomb of charge passing through the cell