The electric field just above the surface of the charged drum of a photocopying machine has a magnitude E of 2.7 x 105 N/C.
(a) The drum has a length of 37 cm and a diameter of 17 cm. What is the total charge in coulombs on the drum?
(b) The manufacturer wishes to produce a desktop version of the machine. This requires reducing the drum length to 21 cm and the diameter to 14 cm. The electric field at the drum surface must not change. What must be the charge in coulombs on this new drum?