Advertisements
Advertisements
प्रश्न
Advertisements
उत्तर
APPEARS IN
संबंधित प्रश्न
If a bulb of 60W is connected across a source of 220V, find the current drawn by it.
Define watt-hour. How many joules are equal to 1 watt-hour?
In a house two 60 W electric bulbs are lighted for 4 hours, and three 100 W bulbs for 5 hours everyday. Calculate the electric consumed in 30 days.
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?
Explain why, filament type electric bulbs are not power efficient.
An electric bulb is rated 250 W, 230 V. Calculate:
- the energy consumed in one hour
- the time in which the bulb will consume 1.0 kWh energy when connected to 230 V mains.
An electric heater is rated 220 V, 550 W. What does this statement mean?
The equation I2R seems to suggest that the rate of heating in a resistor is reduced if resistance decreases, whereas equation P = V2/R suggests just the opposite. How do you reconcile this problem?
A 100-watt electric bulb is used for 5 hours daily and four 60 watt bulbs are used for 5 hours daily. Calculate the energy consumed (in kWh) in the month of January.
A student wants to use an electric heater, an electric bulb and an electric fan simultaneously.
How should these gadgets be connected with the mains? Justify your answer giving three reasons.
