The expected answers were:

(a) (i) Energy is the ability to do work.

(ii) Joule or kilowatt-hour, watt-sec.

(b) Is= 8 mA

IR2= 6 mA

:.IR1= Is-IR2 =(8-6) mA = 2 mA

(i) R1=V/IR1

R1= 24/2 mA = 12 kn

(ii) Total resistance, RT =R1RJRl + R2

=4 X 103 x 12 X 103/(4 x103 + 12 X 103)

=48 x 103/16

=3kn

(iii)

Power = Is
2RT

= (8 X 10-3)2 X 3 X 103= 192 mW

OR

= (ld2R2 + (IR1)2R1

= (6 X 10-3)2 x 4 X 103 + {(2 X 10-3)2 X 12 X 103}

= 0.192 watts = 192 mW

The question was on Direct Current Circuit Theory. It was quite popular with
the candidates.

Many of the candidates who attempted the question got it right. However,
only a few could not parallel the resistors correctly.