Question

A large battery is charged to a potential of 12.5 Volts. The addition of more charge changes the voltage by a negligible amount, a characteristic of the “ideal battery”. A 5amp charger is connected for 48 minutes to increase the stored energy.. a) Determine the amount of charge that is moved. b) Determine the effective resistance of the charging circuit. c) Determine how much work is done during this time? d) Determine the drift speed of the charges in the charging wires, 2mm in diameter of copper with a molar density of 0.14 mol/cc

Answer 1

Solution:

Part(a). The amount of charce moved is given by

(1)

Given that:

Putting these values in equation (1) we find

(2)

Part(b). The effective resistance of the circuit is given by

(3)

Given that:

Substituting these values in equation (3) we get

(4)

Part(c). The work done in this time is given by

(5)

Part(d). Current in the wire is given by

(6)

Given that:

For copper 1 atom = 1 free electron.

Putting these values in equation (6), we find, the drift velocity in the wire as

(7)