Deck 5: Practical Conductors and Insulators

Question 1

In the electrical industry, 'wires' are generally referred to as

A) flex'
B) conductors'
C) cores'
D) cables'

Answer 1

conductors'

Question 2

Place the following conductors in order, from best to worst in terms of their conductivity: aluminium, silver, gold, and copper

A) gold, silver, copper, aluminium
B) silver, gold, copper, aluminium
C) silver, copper, gold, aluminium
D) silver, copper, aluminium, gold

Answer 2

silver, copper, gold, aluminium

Question 3

What property makes aluminium generally unsuitable for domestic wiring systems?

A) poor conductivity compared to copper
B) unreliable pressure connections due to 'cold flow'
C) poor conducting quality of its corrosive film
D) low melting point

Answer 3

unreliable pressure connections due to 'cold flow'

Question 4

A 'cable' consists of

A) one or more conductors
B) one or more insulated conductors
C) one or more insulated conductors enclosed in a protective sheath

Question 5

The term, 'live conductors', refers to a cable's

A) line conductor(s)
B) neutral conductor
C) line and neutral conductors
D) line, neutral, and earth conductors

Question 6

A cable, comprising a line, neutral, and protective (earth) conductor, is termed a

A) single-core conductor'
B) two-core conductor'
C) three-core conductor'

Question 7

Stranded conductors are manufactured to

A) ease their manufacture
B) increase their current ratings
C) increase the flexibility of a cable
D) improve their heat dissipation

Question 8

For a stranded '7/0.85' cable, the figure '0.85' refers to the

A) the diameter of individual strands
B) the cross-sectional area of individual strands
C) the diameter of the conductor
D) the cross-sectional area of the conductor

Question 9

Cables with 'wedge-shaped' cores are manufactured to

A) improve their current-carrying capacity
B) reduce the electrical stress within their insulation
C) improve their flexibility
D) reduce their overall diameter

Question 10

The purpose of a cable's outer sheath is to

A) provide limited mechanical protection
B) prevent the ingress of moisture
C) contain the individual cores
D) all of the above

Question 11

The purpose of armouring a cable is to

A) protect it against mechanical damage
B) relieve and electric stress
C) prevent the ingress of moisture
D) all of the above

Question 12

Insulation is specified, within the UK's Wiring Regulations, in terms of

A) the materials from which it is manufactured
B) its anticipated operating temperature
C) its method of manufacture
D) its insulation resistance

Question 13

The maximum electric field that can be sustained by a dielectric before breakdown occurs' describes an insulator's

A) insulation resistance
B) dielectric strength
C) resistivity
D) voltage gradient

Question 14

For cables manufactured for use in the EU, the insulation colour for a line conductor is

A) red
B) brown
C) black
D) blue

Question 15

For cables manufactured for use in the EU, the insulation colour for a neutral conductor is

A) red
B) brown
C) black
D) blue