Resistance factors

Instructions:

There are 11 questions.

For the multi-choice questions:

  • choose the correct answer
  • write down your answer.

For the calculation questions:

  • calculate the unknown value
  • specify the appropriate unit
  • write down your answer.

Note:

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Question 1

Select the two (2) factors that affect the resistance of a conductor.

  1. Voltage.
  2. Length.
  3. Insulation.
  4. Temperature.

Question 2

Select the conductor with the least resistance.

  1. Nichrome.
  2. Iron.
  3. Nickel.
  4. Copper.

Question 3

What happens to the resistance value of a conductor if its length is increased?

  1. Resistance value increases.
  2. Resistance value decreases.
  3. Resistance value stays the same.

Question 4

In relation to the resistivity of a conductor, what does the abbreviation PTC mean?

  1. Proton temperature current.
  2. Positive temperature current.
  3. Power temperature coefficient.
  4. Positive temperature coefficient.

Question 5

What happens to the resistance value of a NTC material when its temperature increases?

  1. Its resistance decreases.
  2. Its resistance increases.
  3. Its resistance remains the same.

Question 6

How would the resistance value change if a conductor's cross sectional area was halved?

  1. Its resistance will halve.
  2. Its resistance will double.
  3. Its resistance will decrease by four (4) times.
  4. Its resistance will increase by four (4) times.

Question 7

Which copper conductor has more resistance?

  1. A 3mm diameter four meter length.
  2. A 6mm diameter one metre length.
  3. A 6mm diameter two metre length.

Question 8

What is the resistance value of a 200m length of copper conductor that has a cross sectional area of 2.5mm2 (2.5mm squared)?

  1. 0.001376 Ω
  2. 0.01376 Ω
  3. 0.1376 Ω
  4. 1.376 Ω
  5. 13.76 Ω

Question 9

Calculate the voltage drop in a circuit with a current flow of 20amps and a total conductor length of 100 metres.

Note: The conductor has a resistance of 0.002 Ω/m.

Question 10

Calculate the voltage drop in a circuit with a a current flow of 20amps and a total conductor length of 85 metres.

Note: The conductor has a resistance of 0.002 Ω/m.

Question 11

How is the total amount of voltage drop of a conductor affected if the conductor length is doubled?

  1. Voltage drop halves
  2. Voltage drop doubles
  3. Voltage drop multiples x 4
  4. Voltage drop remains the same

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