Module 4 - EPR (Resistivity)

Question 1

What is meant by the term Resistivity

Answer 1

Inherent physical property of a material that describes how strongly it resists the flow of electric current. It depends on the material itself and is independent of its shape or size.

Question 2

Describe and Explain the relationship between resistance and length of wire

Answer 2

As the length of wire increases the resistance of the circuit increases proportionally because double the length means the charge carriers has to pause double the resistance
R α L

Question 3

Describe and explain the relationship between the resistance and the cross-sectional area of the wire

Answer 3

As the cross-sectional area of The Wire increases the resistance decreases because the charge carriers have more paths to take between the positive metal ions
R α 1/I

Question 4

What is the resistivity equation

Answer 4

R = pL/A

Question 5

How do you determine the resistivity of a wire

Answer 5

• Connect voltmeter in parallel to the wire and the ammeter in series to determine a value for V and I. Use R= V/I
• Get values of resistance for different lengths of wire
• Draw graph of R/L
• Gradient will be equal to p/A
  -Use a vernier caliper to determine the A p will be the gradient x the cross-sectional area determined.

Question 6

What is the resistivity order for conductors

Answer 6

x10^-8 ohmM

Question 7

What is the resistivity order for insulators

Answer 7

x10^16