Advertisements
Advertisements
प्रश्न
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.
Advertisements
उत्तर
I = 15 A, R = 8 Ω
Rate of heat produced = Power = I2R = (15)2(8) = 1800 J/s
APPEARS IN
संबंधित प्रश्न
At what frequency is AC supplied to residential houses?
Which one has a higher electrical resistance : a 100 watt bulb or a 60 watt bulb?
Name the commercial unit of electric energy.
What is the meaning of the symbol kWh? Which quantity does it represent?
What is meant by "electric power"?
Calculate the cost of operating a heater of 500 W for 20 hours at the rate of Rs 3.90 per unit.
The table below shows the current in three different electrical appliances when connected to the 240 V mains supply:
| Appliance | Current |
| Kettle | 8.5 A |
| Lamp | 0.4 A |
| toaster | 4.8 A |
- Which appliance has the greatest electrical resistance? How does the data show this?
- The lamp is connected to the main supply by using a thin, twin-cored cable consisting of live and natural wires. State two reasons why this cable should not be used for connecting the kettle to the mains supply.
- Calculate the power rating of the kettle when it is operated from the 240 V mains supply.
- A main takes the kettle abroad where the mains supply is 120 V. What is the current is the kettle when it is operated from the 120 V supply?
An electric bulb is rated ‘100 W, 250 V’. What information does this convey?
An electric bulb is rated ‘100 W, 250 V’. How much current will the bulb draw if connected to a 250 V supply?
An electric toaster draws 8 A current in a 220 V circuit. It is used for 2 h. Find the cost of
operating the toaster if the cost of electrical energy is Rs. 4.50 per kWh.
Define 1 kilowatt hour.
What changes in energy occur in an electric heater?
What is ‘Rating’ of an electric appliance?
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.
How does earthing prevent electrical shock?
Three 250 W heaters are connected in parallel to a 100 V supply, Calculate the energy supply in kWh to the three heaters in 5 hour.
An electric bulb is rated as 100W – 250V. What information does it convey? Calculate the resistance of its filament while glowing.
1 kWh is equal to:
The electrical power and current in the circuit relates by ______
