Find the average speed of the electrons in a 1.0 cm diameter, copper power line, when it carries a current of 20 a.

Average speed

Explanation:

We have given current through power i = 20 A

Diameter d = 1 cm = 0.01 m

So radius r = 0.005 m

So area

Charge on electron e =

We know that current is given by , here n is nuber density of free electron, e is charge on electron, A is area and is average speed

We know that for copper n =

So average speed

b.

explanation:

area of focus