Question

A heating coil is labelled $100W,220V$. 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)

Power of heating coil $=100W$ 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 onefourth of the previous value.
Therefore energy liberated per second becomes 4 times. i.e. $4\times 100=400W$.