# G482 Electricity Definitions

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• Created by: Louise
• Created on: 23-02-14 12:45
Define the Coulomb
One Coulomb is the amount of charge which flows past a point in a circuit in a time of 1s when the current is 1A.
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State Kirchhoff's 1st law
The sum of the currents entering any point in a circuit is equal to the sum of the currents leaving that same point.
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Describe what is meant by the term mean drift velocity
The average displacement of the elctrons along the wire per second. They move slowly in one direction thorugh the metal lattice because they collide with metal ions.
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Define the Ohm
The Ohm is the resistance of a component when a potential difference of 1V is produced per ampere of current.
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State Ohm's Law
for a metallic conductor at constant temperature, the current in the conductor is directly proportional to the potential difference across its ends.
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Define the resistivity of a metal + unit?
resistivity= (Resistance x Cross-sectional area)/length + ohm metre
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Define electromotive force
The energy transferred from source/changed from some form to electrical energy per unit charge.
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Define potential difference
The energy transfer per unit charge from electrical to other forms
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Define V
Energy transferred by unit charge (Joules per Coulomb)
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Define Power
The rate of energy transfer
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What are fuse values measured in?
Amperes
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Define the kilowatt-hour
A unit of energy equal to 3.6MJ OR One kilowatt-hour is the energy transferred by a 1kW devise operating for a time of 1 hour.
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In series how are current/voltage/resistance "shared"?
Current= same at all points. P.d's= add up to give total. Resistances= add up to give total
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In parallel how are current/voltage/resistance "shared"?
Current= shared between branches. Voltage= each branc has same p.d. across its ends. Resistances= give a lower total resistance, need to use the reciprocal formula
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Kirchhoff's 2nd Law
The sum of the emf's around any loop in a circuit is equal to the sum of the p.d.s around the loop.
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## Other cards in this set

### Card 2

#### Front

The sum of the currents entering any point in a circuit is equal to the sum of the currents leaving that same point.

#### Back

State Kirchhoff's 1st law

### Card 3

#### Front

The average displacement of the elctrons along the wire per second. They move slowly in one direction thorugh the metal lattice because they collide with metal ions.

### Card 4

#### Front

The Ohm is the resistance of a component when a potential difference of 1V is produced per ampere of current.

### Card 5

#### Front

for a metallic conductor at constant temperature, the current in the conductor is directly proportional to the potential difference across its ends.