Question

A heating coil is labelled 100 W, 220 V. The coil is cut in half and the two pieces are joined in parallel to the same source. The energy now liberated per second is

• A. 200 W
• B. 400 W
• C. 25 W
• D. 50 W

Answer 1

Answer: (B)

400 W

Answer 2

The correct option is(C): 400 W.
Power of heating coil = 100 W and voltage (V) = 220 volts.
When the heating coil is cut into two equal parts and these parts are joined in parallel, the resistance of the coil is reduced to one fourth of the previous value.
Therefore energy liberated per second becomes 4 times, i.e. $4 \times 100$
$=400\, W.$