Flashcards in Modules 4 Definitions Deck (71)

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1

## Conductors

###
A material that allows the flow of electrical charge. Good conductors

have a larger amount of free charge carriers to carry a current.

2

## Conservation of charge

### The total charge in a system cannot change

3

## Conventional current

###
The flow from positive to negative, used to describe the

direction of current in a circuit.

4

## Coulomb

### The unit of charge.

5

## Electric current

### The rate of flow of charge in a circuit.

6

## Electrolytes

###
Substances that contain ions that when dissolved in a solution, act

as charge carriers and allow current to flow.

7

## Electron Flow

###
The opposite direction to conventional current flow. Electrons flow

from negative to positive.

8

## Elementary charge

###
The smallest possible charge, equal to the charge of an

electron.

9

## Insulators

###
A material that has no free charge carriers and so doesn’t allow the

flow of electrical charge.

10

## Kirchhoff's First Law

###
A consequence of the conservation of charge. The total

current entering a junction must equal the total current leaving it.

11

## Mean Drift Velocity

###
The average velocity of an electron passing through an

object. It is proportional to the current, and inversely proportional to the number of

charge carriers and the cross-sectional area of the object.

12

## Quantisation of Charge

###
The idea that charge can only exist in discrete packets

of multiples of the elementary charge.

13

## Semiconductors

###
A material that has the ability to change its number of charge

carriers, and so its ability to conduct electricity. Light dependent resistors and

thermistors are both examples.

14

## Diode

###
A component that allows current through in one direction only. In the

correct direction, diodes have a threshold voltage (typically 0.6 V) above which

current can flow.

15

## Electromotive Force

###
The energy supplied by a source per unit charge passing

through the source, measured in volts.

16

## Filament Lamp

###
A bulb consisting of a metal filament, that heats up and glows to

produce light. As the filament increases in temperature, its resistance increases

since the metal ions vibrate more and make it harder for the charge carriers to

pass through.

17

## I-V Characteristics

###
Plots of current against voltage, that show how different

components behave.

18

## Kilowatt-Hour

###
A unit of electrical energy. It is usually used to measure domestic

power consumption.

19

## Light-Dependent Resistor

###
A light sensitive semiconductor whose resistance

increases when light intensity decreases.

20

## Ohm

### The unit of resistance.

21

## Ohmic Conductor

###
A conductor for which the current flow is directly proportional

to the potential difference across it, when under constant physical conditions.

22

## Ohm's Law

###
The current and potential difference through an ohmic conductor

held under constant physical conditions are directly proportional, with the constant

of proportionality being resistance.

23

## Potential Difference

###
The difference in electrical potential between two points in a

circuit. It is also the work done per coulomb to move a charge from the lower

potential point to the higher potential point. It is measured in Volts.

24

## Power

###
The rate of energy transfer in a circuit. It can be calculated as the product

of the current and the potential difference between two points. It is measured in

Watts.

25

## Resistance

### A measure of how difficult it is for current to flow through a material.

26

## Resistivity

###
A measure of how difficult it is for charge to travel through a material.

It is proportional to the object’s resistance and cross-sectional area, and inversely

proportional to the object’s length. It is measured in Ohm metres.

27

## Resistor

### A device that has a fixed resistance and follows Ohm’s law.

28

## Volt

### The unit of potential difference.

29

## Conservation of Energy

### Energy cannot be created or destroyed - it can only be transferred into different forms.

30