Question 21
Current ElectricityThe effect of closing the key K in the circuit shown in Fig. 2 would be to
- A.increase the current by 0.6 A
- B.reduce the current by 0.6 A
- C.reduce the current by 0.4 A
- D.increase the current by 0.4 A
- E.keep the current unchanged.
Show the answer and explanation
Answer: D (increase the current by 0.4 A)
Explanation
With K open: R = 8 + 2 = 10 Ω, I = 6/10 = 0.6 A. With K closed the second 8 Ω goes in parallel (4 Ω), so R = 6 Ω and I = 1 A: an increase of 0.4 A.