Advertisements
Advertisements
Question
What is the meaning of the symbol kWh? Which quantity does it represent?
Advertisements
Solution
The symbol KWh stands for kilowatt-hour. It is the commercial unit of electrical energy.
APPEARS IN
RELATED QUESTIONS
1 calorie = _________ joule.
An electric bulb is connected to a 220 V power supply line. If the bulb draws a current of 0.5 A, calculate the power of the bulb.
How many joules are there in one kilowatt-hour?
Which of the following is the most likely temperature of the filament of an electric light bulb when it is working on the normal 220 V supply line?
(a) 500°C
(b) 1500°C
(c) 2500°C
(d) 4500°C
An electric bulb is rated ‘100 W, 250 V’. How much current will the bulb draw if connected to a 250 V supply?
A geyser is rated 1500 W, 250 V. This geyer is connected to 250 V mains. Calculate:
(i) the current drawn
(ii) the energy consumed in 50 hours, and
(iii) the cost of energy consumed at Rs. 4.20 per kWh
The coil of an electric bulb takes 40 watts to start glowing. If more than 40 W are supplied, 60% of the extra power is converted into light and the remaining into heat. The bulb consumes 100 W at 220 V. Find the percentage drop in the light intensity at a point if the supply voltage changes from 220 V to 200 V.
What is the current in the circuit shown (Fig. )
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?
Point out two main disadvantages of ‘Tree System’.
Name three main characteristics of an heating element.
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 do you understand by ‘earthing’? What are the advantages of earthing in a household electric circuit? Explain, how it is done?
How does earthing prevent electrical shock?
A torch bulb is rated at 3 V and 600 mA. Calculate it’s
- power
- resistance
- energy consumed if it is used for 4 hours.
What is the commercial unit of electrical energy?
What is the commercial unit of electrical energy? Represent it in terms of joules.
Using a long extension cord in which each conductor has a resistance of 8Ω, a bulb marked as '100 W, 200 V' is connected to a 220 V dc supply of negligible internal resistance as shown in the figure. The power delivered to the bulb is ______ W.
