Current Electricity

Question 1

Current

Answer 1

Q/t

Question 2

An ammeter

Answer 2

A device that measures current and must be connected in series

Question 3

Direct current

Answer 3

Always flows in one direction

Question 4

Alternating current

Answer 4

Constantly changing direction

Question 5

Voltmeter

Answer 5

Device that measures voltage and must be connect in parallel

Question 6

Ohm

Answer 6

The unit of resistance. A conductor has a resistance of 1 ohm if a current of 1 A passes through it when a p.d. Of 1V is applied

Question 7

Ohms law

Answer 7

The current flowing through a conductor is directly proportional to the p.d. across it, if the temp remains constant

Question 8

Electrolysis

Answer 8

The passing of an electric current through a liquid causing a chemical reaction

Question 9

A fuse

Answer 9

A safety device consisting of a piece of wire which melts when a current above a pre-set value passes through it

Question 10

A miniature circuit breaker (mcb)

Answer 10

A safety device which breaks the circuit if it detects a current above above a pre set value

Question 11

A residual current device (RCD)

Answer 11

A safety device that breaks the circuit if it detects a current difference between live and neutral above a pre set value

Question 12

A radial circuit

Answer 12

Where a separate live and neutral wire are connected from the distribution box to an appliance which uses large current

Question 13

A ring circuit

Answer 13

Where the live terminals of each socket are connected in a ring so that current can flow both ways

Question 14

Bonding

Answer 14

A safety precaution whereby all metal pipes, taps and tanks are earthed

Question 15

Kilowatt-hour

Answer 15

The amount of energy used by a 1000 W appliance in 1 hour

Question 16

A semiconductor

Answer 16

A substance whose resistivity is between that of a good conductor and a good insulator

Question 17

Holes

Answer 17

Positively charged gaps in a substance which are created when electrons break free from covalent bonds

Question 18

Doping

Answer 18

The addition of impurities to a semi conductor to increase its conductivity

Question 19

Intrinsic conduction

Answer 19

Occurs in a pure semiconductor when there is an equal number of electrons moving from - to + and holes moving in the opposite direction

Question 20

Extrinsic conduction

Answer 20

An increased rate of conduction due to the addition of impurities

Question 21

Thermistor

Answer 21

A semiconductor whose resistance decreases as temp increases

Question 22

Light dependent resistor (LDR)

Answer 22

A semiconductor whose resistance decreases as light intensity increases

Question 23

Ampere

Answer 23

The current flowing in two parallel conductors placed 1m apart in a vacuum that causes a force of 2x10^-7 Nm-1

Question 24

N type semiconductor

Answer 24

Semiconductor in which electrons are the majority charge carriers

Question 25

P type semiconductor

Answer 25

A semiconductor in which holes are the majority charge carriers