3.5.1.3 Resistivity

Question 1

What is resistivity?

Answer 1

The measure of how easily a material conducts electricity, how much a material opposes the flow of electric current through it
The product of resistance and cross-sectional area, divided by the length of the material
Gives the value of resistance through a material of length 1m and cross-sectional area 1m^2

Question 2

What is the relationship between temperature and resistance for a metal conductor?

Answer 2

An increase in temperature of a metal conductor increases its resistance

Question 3

Why does an increase in the temperature of a metal conductor increase its resistance?

Answer 3

The atoms in the metal gain kinetic energy and move more, causing more collisions between electrons carrying charge and the atoms, slowing the electrons down, decreasing the current and therefore the resistance

Question 4

What is the relationship between temperature and resistance for a thermistor?

Answer 4

As the temperature of a thermistor increases, its resistance decreases

Question 5

What is a superconductor?

Answer 5

A material that has zero resistivity below its critical temperature (different for each material)

Question 6

What are examples of applications of superconductors?

Answer 6

Power cables - reduces energy loss through heat to zero
Production of strong magnetic fields - could be used in maglev trains where there would be no friction between the train and rail, or in certain medical applications