Advertisements
Advertisements
प्रश्न
When a current of 4.0 A passes through a certain resistor for 10 minutes, 2.88 × 104 J of heat are produced. Calculate
the power of the resistor.
the voltage across the resistor.
Advertisements
उत्तर
I = 4.0 A
H = 2.88 x 104 J
t = 10 minutes = 10 x 60 = 600 s
Power `=H/t=(2.88x10^4)/60=48W`
V`=p/I=48/4=12V`
APPEARS IN
संबंधित प्रश्न
What determines the rate at which energy is delivered by a current?
Which of the following terms does not represent electrical power in a circuit?
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?
Name two gases which are filled in filament type electric light bulbs.
A potential difference of 6 V is applied across a 3 Ω resistor. What is the current flowinq throuqh the circuit?
Two resistors A and B of 4 Ω and 6 Ω, respectively are connected in parallel. The combination is connected across a 6 volt battery of negligible resistance. Calculate the power dissipated in each resistor.
What does the unit kilowatt hour measure? Define it.
An electric current is passed through a metallic wire. The wire gets heated up. Give the reason. Is it possible to melt the wire by passing a heavy current?
Household wiring for lamp connections can either be done in parallel or in series.Which one would you prefer? Give a reason for your answer.
An electric filament lamp is connected to a supply of voltage higher than the recommended value. Give reasons, why compared with a normal performance, the lamp emits a brighter light and its life is shortened.
What is the order of current drawn by appliances connected to the ‘light circuit’ of a household?
You are required to connect a bulb, a fan and a socket outlet to the mains in one set A and an air-conditioner and a refrigerator to the mains in other set B. Will you recommend the wire of same thickness and same insulation in both? explain your answer.
A bulb is marked 100W, 220V and an electric heater is marked 2000 W, 220 V.
(i) What is the ratio between the resistances of these two devices?
(ii) How does the power-voltage rating of a device help us to decide about the type of leads (connecting wires) to be used for it?
(iii) In which of the above two devices, a thicker connecting wire of lead is required?
An electrical appliance is rated 1500 W, 250 V. This appliance is connected to 250 V mains. Calculate:
(i) the current drawn,
(ii) the electrical energy consumed in 60 hours,
(iii) the cost of electrical energy consumed at Rs. 2.50 per kWh.
A consumer uses 4 lamps of 60 watt, 2 lamps of 40 watt, and 2 lamps of 100 watt. All these are used for 6 hour daily. Find the total bill for 30 days when the rate of energy is 75 paise per unit and the meter rent is Rs. 1.
The following table gives the electrical appliances used, their power and the average time for which they are used each day in a home. Estimate the monthly electricity bill if the rate is 60 paise per unit.
| Sr.no. | Name | Nos. | Power rating | Time/day |
| 1 | Bulb | 4 | 100 W | 7.5 hr |
| 2 | Fans | 2 | 50 W | 10 hr |
| 3 | T.V. | 1 | 100 W | 2 hr |
| 4 | Iron | 1 | 500 W | 1 hr |
| 5 | Electric stove | 1 | 750 W | 2 hr |
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 ______.
1 kWh = ______ J.
