The effect of closing the key K in the circuit shown above would be to
-
A.
increase the current by 0.6A -
B.
reduce the current by 0.6A -
C.
increase the current by 0.4A -
D.
keep the current unchanged
Correct Answer: Option C
Explanation
When K is open, the total resistance
R = 8(Omega) + 2(Omega) = 10(Omega)
I = (frac{V}{R}) = (frac{6}{10})
= 0.6A
When K is closed, we have
(frac{1}{R}) = (frac{1}{8}) + (frac{1}{8})
⇒ (frac{1}{R}) = (frac{1}{4})
⇒ R = 4(Omega)
The total resistance R = 4(Omega) + 2(Omega)
= 6(Omega)
I = (frac{6}{6})
= 1A
Hence, I = 1A – 0.6A = 0.4A increase