Heat produced in a wire of resistance $R$ due to current flowing at constant potential difference is proportional to

Assertion: Long distance power transmission is done at high voltage.
Reason: At high voltage supply,power losses are less.

$A$ constant voltage is applied between two ends of a metallic wire. If the length is halved and the radius of the wire is doubled,the rate of heat developed in the wire will be

It takes $12$ minutes to boil $1$ litre of water in an electric kettle. Due to some defect, it becomes necessary to remove $20\%$ of the turns of the heating coil of the kettle. After repair, how much time will it take to boil $1$ litre of water?

If the length of the filament of a heater is reduced by $10\%$,the power of the heater will

$A\, 5\, ^oC$ rise in the temperature is observed in a conductor by passing some current. When the current is doubled,then the rise in temperature will be equal to ............. $^oC$.