Question
Physics Question on Electronic devices
The figure below shows a part of an electric circuit. The current marked IA is:
A
1 A
B
1.3 A
C
1.7 A
D
3 A
Answer
1 A
Explanation
Solution
Using Kirchhoff’s Current Law at point A, the sum of the currents entering the junction must equal the sum of the currents leaving the junction.
1. The incoming currents at point A are IA and 0.2A from the top. 2. The outgoing currents are 1.2A and 0.2A downwards.
Applying Kirchhoff’s Law:
IA +0.2 = 1.2+0.2
Simplifying:
IA +0.2 = 1.4 ⇒ IA=1.2A
Thus, the current IA is 1.2A.