Question

1. (a) How many electrons will pass a fixed point in a 2000 Watt heater in 1 minute if the applied
voltages are 240 V? [5]
(b) The AWG (American Wire Gauge) is used as a standard method denoting wire diameter,
measuring the diameter of the conductor (the bare wire) with the insulation removed. An
AWG # 12 copper wire (a size in common use in residential wiring) contains approximately
2.77 x 1023 free electrons per meter length, assuming one free conduction electron per atom.
What percentage of these electrons will pass a fixed cross section in one second if the conductor
carries a constant current of 1.5 A? [5]
(c) Electric current always takes a path with minimum resistance. Prove this mathematically by
using 2 resistors of any values of your choice. Assume any value of the source voltage. [5]
(d) Find out the maximum voltage that can be applied across a 0.25W, 6.8 kΩ resistor without
burning it up.

Answer 1

Number of electrons passing through the fixed point = 3.125 × 10²¹ electrons.

Answer 2

number of electrons passing through the fixed point =3.125×10^21 electrons.