Magnified and diminished image

Q.

An electric fan runs from the 230 V mains. The current flowing through it is 0.4 A. At what rate is electrical energy transferred by the fan ?

Q.

A moving car encounters air resistance which is proportional to the square of the speed of the car. The ratio of the power required at $40km{h}^{-1}$ to that required at $80km{h}^{-1}$, with the same braking power, is

1. $1:6$

2. $1:8$

3. $1:16$

4. $16:1$

Q. A bulb is rated at 200V, 40W. What is the resistance? 5 such bulbs are lighted for 5 hours. Calculate the electrical energy consumed. Find the cost if the rate is Rs 5.10 per kWh

Q. What is power of bulb rated at 2.5V , 500milliampere .

Q.

If the length of the filament of a heater is reduced by 10% by cutting it, the power of the heater will?

Q. A torch bulb is rated 2.5V and 750mA. Calculate:
a) it's power
b) it's resistance
c) then energy consumed if this bulb is lighted for 4 hours

Q. A torch bulb is rated 5v and 500mA calculate it's 1.power 2.Resistance 3.Energy consumed when it is lighted for 6 hours everyday.

Q.

What is the power factor formula?

Q. An electric heater has a resistance of 12 ohm and is operated from a 220 v line . If no heat escapes from it, how much time is required to raise the temperature of 40 kg of water from 15 c to 80 celcius?

Q.

A torch bulb is rated 2.5 volts and 750 mA. Calculate:(i)it's resistance (ii) it's power (iii) energy consumed if this bulb is lighted for four hours.

Q.

.Calculate the power loss in an electrical transmission cable, 15 km long, carrying a current of 100A at a potential of 200 kV. The resistance per km of the cable is 0.2 Ω.

Q.

Power in an AC circuit is equal to

Q.

Q.

An electric heater is rated 1000 W-200 V. The resistance of the heating element will be:

1. 200 Ω

2. 1000 Ω

3. 5 Ω

4. 40 Ω

Q.

A geyser has a label$2kW,240V$. What is the cost of using it for$30minute$, if the cost of electricity is$Rs3$ per commercial unit?

Q.

How is energy conserved when power is stepped up from 11kv to 132kv?

Q.

Formula of generated energy with example

Q.

An electrical appliance is rated 1500 W- 250 V. This appliance is connected to 250 V mains. Calculate:

The electrical energy is consumed in 60 hours.

Q. An electric fan runs from the 230 V mains. The current flowing through it is 0.4 A. At what rate is electrical energy transferred by the fan?

Q.

calculate the current through a 60 watt lamp rated for 250V.if the line voltage falls to 200V how is the power consumed by the bulb affected.

Q. A house has 3 tube lights, two fans and a Television. Each tube light draws 40W. The fan draws 80W and the Television draws 60W. On the average, all the tube lights are kept on for five hours, two fans for 12 hours and the television for five hours every day. Find the cost of electric energy used in 30 days at the rate
of Rs. 3.00 per Kwh. (AS, )

Q.

what is the commercial unit of electric power?is it same as the commercial unit of electrical energy?

Q.

Calculate the current through a 60W lamp rated for 250V. If the line voltage falls to 200V, how is the power consumed by the lamp affected.