Deck 4: Resistance

Question 1

Resistance acts to

A) slow down the current drifting in a conductor
B) decrease the current drifting in a conductor
C) increase the current drifting ina conductor
D) limit the current drifting in a conductor

Answer 1

limit the current drifting in a conductor

Question 2

The resistance of a conductor will increase if the

A) length of the conductor is reduced
B) cross-sectional area of the conductor is reduced
C) resistivity of the conductor is reduced
D) the current through the conductor is reduced

Answer 2

cross-sectional area of the conductor is reduced

Question 3

Doubling the diameter of a circular conductor will act to

A) double its resistance
B) half its resistance
C) reduce its resistance by a quarter
D) quadruple its resistance

Answer 3

reduce its resistance by a quarter

Question 4

A material's resistivity varies with

A) its length
B) its cross-sectional area
C) its temperature
D) the shape of its cross-section

Question 5

The SI unit for resistivity is the

A) ohm
B) ohm per metre
C) ohm metre
D) ohm per cubic metre

Question 6

Halving the current through a conductor will

A) halve its resistance
B) double its resistance
C) quadruple its resistance
D) have no effect on its resistance

Question 7

Increasing the temperature of a pure metal conductor will generally

A) reduce its resistance
B) increase its resistance
C) have no effect on its resistance
D) either a or b

Question 8

Increasing the temperature of most insulating materials will

A) reduce their resistance
B) increase their resistance
C) have no effect on their resistance
D) either a or b

Question 9

The 'ohm' is defined in terms of the

A) ratio of voltage to current
B) resisitivity of a material
C) length, cross-sectional area, and resistivity of a conductor
D) the type of conductor

Question 10

The insulation resistance for a length of cable is 100 megohms. What would be its value if the cable were five times as long?

A) 20 megohms
B) 50 megohms
C) 100 megohms
D) 500 megohms

Question 11

The 'a.c. resistance' is of a conductor is __________ than its d.c. resistance, due to a property called __________

A) slightly lower, reactance
B) slightly lower, 'skin effect'
C) slightly higher, reactance
D) slightly higher, 'skin effect'

Question 12

A.C. resisitance' is caused by a conductor's

A) increase in resistivity due to frequency
B) loss of effective c.s.a. due to frequency
C) increase in collisions between electrons due to frequency
D) increase in temperature due to frequency