Resistance and Resisitvity

Question 1

What can have an increased effect on Resistance?

Answer 1

Temperature
Length of wire

Directly Proportional

Question 2

What can have a decreased effect on Resistance?

Answer 2

Cross - Sectional Area of the wire
Inversely Proportional

Question 3

Define the term Resistivity.

Answer 3

This is used to describe the electrical property of a material.

Question 4

What materials have different values of Resistivity?

Answer 4

Conductors- 10 to the power of minus 8
Insulators- 10 to the power of 16
Semiconductors- Negligible

Question 5

What is the experiment to determine resistivity?

Answer 5

Investigate how the resistance of a wire varies with its length. We can determine Potential Difference across different lengths of wire. Also the current so then we use Ohms Law to work out Resistance for each length.
As R is directly proportional to L. We get a graph with a straight line through the origin. Using y=mx+c the gradient is resistivity over cross sectional area.
Multiply the gradient by the cross sectional area and we have the resistivity of the wire.