Heat And Power Developed In A Resistor - Practice Questions & MCQ

If the voltage across a bulb rated 220 volt - 100-watt drops by 2.5% of its rated value, the percentage of the rated value by which the power would decrease is:

A filament bulb (500 W, 100 V) is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R

The charge flowing through a resistance R varies with time t as Q = at - bt², where a and b are positive constants. The total heat produced in R is:

Two electric bulbs have tungsten filaments of the same length. If one of them gives and the other , then

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

A line having a total resistance of delivers at to a small factory.The efficiency of transmission is nearly -

A capacitor of capacitance has . Its connected to an identical capacitor through a resistance. Find heat produced in the resistance.
 

An electric bulb rated for is used in a circuit having supply. Find the resistance that must be put in series with the buck, so that the bulb draws .
 

A Storage battery with emf 15.6V loaded with external resistance produces a current 1A. In this case, the potential difference between the terminals of the storage battery equals 2.5 volts. Find the thermal power generated in the battery and the net power supplied by the battery for external circuit.
 

A current carrying wire heats a metal rod. The wire provides a constant power (P) to the rod. The metal rod is enclosed in an insulated container it is observed that the temp (T) in the metal rod changes with time (t) as

The heat capacity of the metal is