A10

A charge of 6x10^-6 C exerts a force of 940 N on a charge of 6x10^-6 C.

a) How far apart are the charges?

b) Is this an attractive or repulsive force?

B10

A power of 100 kW is delivered a long distance by a pair of power lines, between which the voltage is 12,000 V.

a) What is the current in the line?

b) If each of the two lines has a resistance of 10 ?, what is the change of voltage along each line?