Advertisements
Advertisements
Question
State whether an electric heater will consume more electrical energy or less electrical energy per second when the length of its heating element is reduced. Give reasons for your answer.
Solution
The electric heater will consume more electrical energy when the length of its heating element is reduced because resistance is directly proportional to length `(R=rhol/A)`. Hence, resistance will decrease. Power is inversely proportional to resistance`(P=V^2/R)`. Hence, power will increase.
Thus, a decrease in resistance means an increase in the power consumed.
APPEARS IN
RELATED QUESTIONS
An electric bulb is rated at 220 V, 100 W. What is its resistance?
An electric heater of resistance 8 Ω takes a current of 15 A from the mains supply line. Calculate the rate at which heat is developed in the heater.
A current passes through a resistor. Let K1 and K2 represent the average kinetic energy of the conduction electrons and the metal ions, respectively.
An electric bulb, when connected across a power supply of 220 V, consumes a power of 60 W. If the supply drops to 180 V, what will be the power consumed? If the supply is suddenly increased to 240 V, what will be the power consumed?
Name the physical quantity which is measured in kW.
Two electric lamps each rating 100 W, 110 V are connected in series to a 220 V power supply and two other electric lamps each of marking 100 W, 220 V are connected in parallel to the same power supply. Will anyone of the two combinations give more light than the other? Give a reason for your answer.
State the reason why, in a three pin plug, the earth pin is longer and thicker than the other two.
An Electric bulb is marked 100 W, 230 V. What find the energy consumed by the bulb in one hour.
If a heater coil rated lkW, 220 V is connected in series with an electric bulb of 100 W, 220 V and are supplied 200V, power consumed by the bulb in this circuit is ______.
