Chapter 1: Unit's associated with basic electrical circuits.

Question 1

Define an electric current.

Answer 1

Electric current is the rate of movement of change.

Question 2

State the symbol for electric current and the unit.

Answer 2

Symbol: I
Unit: Ampere

Question 3

State the 3 main effects of electric current.

Answer 3

-Magnetic effect
-Heating effect
-Chemical effect

Question 4

List examples of the magnetic effect.

Answer 4

-Bells
-Relays
-Motors
-Generators
-Transformers
-Telephones

Question 5

List examples of the heating effect

Answer 5

-Cookers
-Water heaters
-Electric fires
-Irons
-Furnaces
-Kettles
-Soldering irons

Question 6

List examples of the chemical effect

Answer 6

-Primary and secondary cells
-Electroplating

Question 7

Describe direct current

Answer 7

Direct current is one that flows in one direction only around a circuit

Question 8

Describe alternating current

Answer 8

Alternating current is one that constantly changes direction in a circuit, rising to a maximum in one direction before falling to zero and then rising to a maximum in the opposite direction.

Question 9

Define a conductor

Answer 9

A material having a low resistance that allows electric current to flow through it.

Question 10

List examples of conductors.

Answer 10

-Copper
-Aluminium
-Brass
-Platinum
-Silver
-Gold
-Carbon

Question 11

Define an insulator.

Answer 11

A material having a high resistance that does not allow electric current to flow through it.

Question 12

List examples of insulators.

Answer 12

-Plastic
-Rubber
-Glass
-Porcelain
-Air
-Paper
-Cork
-Mica
-Ceramics
-Certain oils

Question 13

Define a semiconductor

Answer 13

A material with an electrical conductivity between that of a conductor and an insulator, it is neither a good insulator nor a good conductor under ordinary conditions, but can be made to exhibit some of the properties of each.

Question 14

List examples of semiconductors

Answer 14

-Silicon
-Germanium