Current Electri...

If current in an electric bulb changes by 1%, then the power will change by

Two identical batteries, each of e.m.f. 2 volt and internal resistance 1.0 ohm are available to produce heat in an external resistance R = 0.5 ohm by passing a current through it. The maximum Joulean power that can be developed across R using these batteries is

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

The heating coils rated at 220 volt and producing 50 cal/sec heat are available with the resistances 55Ω, 110Ω, 220Ω and 440Ω. The heater of maximum power will be of

The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use

A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be

An electric heater kept in vacuum is heated continuously by passing electric current. Its temperature

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

A coil takes 15 min to boil a certain amount of water, another coil takes 20 min for the same process. Time taken to boil the same amount of water when both coils are connected in series

An electric bulb of 100 watt is connected to a supply of electricity of 220 V . Resistance of the filament is