Electric circuits definitions

Question 1

Conductors

Answer 1

A material that allows the flow of electrical charge. Good conductors
have a larger amount of free charge carriers to carry a current.

Question 2

Conventional Current

Answer 2

The flow from positive to negative, used to describe the direction of current in a circuit.

Question 3

Electric Current

Answer 3

​The rate of flow of charge in a circuit.

Question 4

Electrolytes

Answer 4

Substances that contain ions that when dissolved in a solution, act as charge carriers and allow current to flow.

Question 5

Electron Flow

Answer 5

​The opposite direction to conventional current flow. Electrons flow from negative to positive.

Question 6

Elementary Charge

Answer 6

The smallest possible charge, equal to the charge of an electron.

Question 7

Insulators

Answer 7

A material that has no free charge carriers and so doesn’t allow the flow of electrical charge.

Question 8

Kirchhoff’s First Law

Answer 8

​A consequence of the conservation of charge. The total current entering a junction must equal the total current leaving it.

Question 9

Mean Drift Velocity

Answer 9

​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.

Question 10

Quantisation of Charge

Answer 10

The idea that charge can only exist in discrete packets of multiples of the elementary charge.

Question 11

Semiconductors

Answer 11

​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.

Question 12

Diode

Answer 12

​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.

Question 13

Electromotive Force

Answer 13

The energy supplied by a source per unit charge passing through the source, measured in volts.

Question 14

Kilowatt-Hour

Answer 14

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

Question 15

Ohmic Conductor

Answer 15

A conductor for which the current flow is directly proportional to the potential difference across it, when under constant physical conditions.

Question 16

Ohm’s Law

Answer 16

The current and potential difference through an ohmic conductor held under constant physical conditions are directly proportional, with the constant of proportionality being resistance.

Question 17

Potential Difference

Answer 17

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.

Question 18

Power

Answer 18

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.

Question 19

Internal Resistance

Answer 19

The resistance to the flow of charge within a source. Internal resistance results in energy being dissipated within the source.

Question 20

Kirchhoff’s Second Law

Answer 20

​A consequence of the conservation of energy. The sum of the voltages in any closed loop must equal zero.

Question 21

Lost Volts

Answer 21

The difference between a source’s emf and the terminal voltage. It is equal to the potential difference across the source’s internal resistance.

Question 22

Potential Divider

Answer 22

A method of splitting a potential difference, by connecting two resistors in series. The total potential difference is split in the ratio of their resistances.

Question 23

Sensor Circuits

Answer 23

A circuit that reacts to external conditions. They commonly involve a semiconductor connected in a potential divider arrangement.

Question 24

Terminal PD

Answer 24

The potential difference across the terminals of a power source. It is equal to the source’s emf minus any voltage drop over the source’s internal resistance.