# Physics OCR AS unit 2

Define words

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• Created by: emma
• Created on: 31-05-11 14:08

Define the:

Coulomb

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## The Coulomb

The charge passing a point in a circuit where there is a current of 1 amp for 1 second

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## Potential Difference

Define:

Potential difference (p.d)

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## P.d

Measure of energy or work done by each coulomb of charge as it moves from one point to another

Unit: VOLT (v)

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Define:

The volt

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## The volt

One volt is the potential difference between 2 points when one joule of energy is transferred by one coulomb of charge passing from one point to another.

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## Electromotive force (e.m.f)

Define:

electromotive force (emf) of a source such as a cell or power supply

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## E.m.f

The electrical energy gained by each coloumb of charge that passes through the power supply.

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Define:

resistance

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## resistance

The resistance of a wire is defined as the ratio of the potential difference V across the wire the current I in it

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Define:

The ohm

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## ohm

measurement of resistance, expressing the resistance in a circuit transmitting a current of one ampere when subjected to a potential difference of one volt

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## resistivity

Define:

Resistivity of a material

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## resistivity

The resistivity of a material is numerically equal to the resistance between opposite faces of a cube of unit length, height and cross sectional area.

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## kilowhatt hour

Define:

The kilowatt-hour (kWh) as a unit of energy

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## kWh

A measure of electrical energy equivalent to a power consumption of 1,000 watts for 1 hour.

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Define:

Displacement

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## displacement

Displacement of a particle on a wave is its distance from its rest position

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Define:

Amplitude

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## amplitude

The amplitude is the maximum displacement of a particle in the wave

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Define:

Wavelength

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## wavelength

The distance between two neighbouring peaks or two neighbouring troughs or two different points on the wave which are vibrating together in phase. It is the distance moved by the wave during one oscillation of the source of the waves.

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Define:

Period

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## period

The period of the wave is the time taken for one particle to complete one vibration or one cycle

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Define:

Phase difference

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## phase difference

The phase angle by which one periodic disturbance or wavefront lags behind or precedes another in time or space.

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Define:

Frequency

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## frequency

The number of complete vibrations per unit time

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Define:

Speed of a wave

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## speed of a wave

speed at which energy is transferred along the wave (for a progressive wave)

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Define:

Node

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## node

When there is no vibration on a stationary wave - minimum amplitude

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Define:

Antinode

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## antinode

place of maximum amplitude

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## fundamental mode of vibration

Define:

Fundamental mode of vibration

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## fundamental mode of vibration

when the wave pattern of a stationary wave has a single loop

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Define:

Harmonics

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## harmonics

any of a series of musical tones whose frequencies are integral multiples of the frequency of a fundamental tone.

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## electronvolt

Define:

The electronvolt (eV) as a unit of energy

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## electronvolt

The energy gained by an electron when it moves through a potential difference of 1 volt. 1eV = 1.6x10(-19) J

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Define:

Work function

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## work function

minimum amount of energy necessary for an electron to escape from the surface

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## threshold frequency

Define:

Threshold frequency

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## threshold frequency

the lowest frequency of light required to eject a photoelectron

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