Advertisements
Advertisements
Question
If a bulb of 60W is connected across a source of 220V, find the current drawn by it.
Advertisements
Solution
Power P = 60W, Voltage V = 220. To find eye ?
We have current `I = P/V = 60/220= 0.272 A`
APPEARS IN
RELATED QUESTIONS
Which of the following terms does not represent electrical power in a circuit?
Define watt-hour. How many joules are equal to 1 watt-hour?
Which uses more energy: a 250 W TV set in 1 hour or a 1200 W toaster in 10 minutes?
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?
Electrical power P is given by the expression P = (Q × V) ÷ time. What do the symbols Q and V represent?
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?
Write the SI units for:
(a) Electric current
(b) Potential difference
(c) Charge.
State the S.I. units of electrical power and electrical energy.
(i) Define the household unit of electricity.
(ii) What is the voltage of the electricity that is generally supplied to a house?
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?
Why is heating element wound on a long porcelain rod in a room heater.
‘The current rating of a fuse is 5A’. Comment on this statement.
Give two precautious that you would take while putting off an electric switch.
How does the heat produced by die passage of current in a metallic wire depend on the resistance of the wire.
State the reason why, in a three-pin plug, the earth pin is longer and thicker than the other two.
1 kWh = ____________
The electrical power and current in the circuit relates by ______
An overhead tank of capacity 10 k litre is kept at the top of building 15 m high. Water falls in tank with speed 5`sqrt2` m/s. Water level is at a depth 5 m below ground. The tank is to be filled in `1/2` hr. If efficiency of pump is 67.5% electric power used is ______ W.
