Question

1. Find the value of current ‘I’ in Figure 2 given below.
   

2. State the conservation principle on which your calculation is based.

Answer 1

(a) To find the value of I , we use Kirchhoff’s Current Law (KCL), which states that the total current entering a junction must equal the total current leaving it.

Looking at the diagram, we can group the currents:

Currents Entering: 8 A and 7 A

Currents Leaving: I, 5 A and 3 A

Sum of Entering Currents = Sum of Leaving Currents

8 A + 7 A = I + 5 A + 3 A

15 A = I + 8 A

I = 15 A − 8 A

= 7 A

(b) The calculation is based on the Law of Conservation of Charge.

Since electric charge cannot be created or destroyed at a junction in a steady-state circuit, the amount of charge (current) flowing into a point must exactly match the amount flowing out.