Advertisements
Advertisements
Question
Which uses more energy: a 250 W TV set in 1 hour or a 1200 W toaster in 10 minutes?
Advertisements
Solution
Energy consumed by the TV set,
E = p × t
= 250 × 1
= 250 Wh
Energy consumed by the toaster,
E = p × t
`= 1200 Wxx10/60h (10 min = 10/60h)`
= 200 Wh
Thus, it is clear that the TV set consumes more electrical energy.
APPEARS IN
RELATED QUESTIONS
Define watt-hour. How many joules are equal to 1 watt-hour?
An electric kettle connected to the 230 V mains supply draws a current of 10 A. Calculate:
(a) the power of the kettle.
(b) the energy transferred in 1 minute.
When an electric lamp is connected to 12 V battery, it draws a current of 0.5 A. The power of the lamp is:
(a) 0.5 W
(b) 6 W
(c) 12 W
(d) 24 W
Define Kilo watt hour.
Name two common material used for heating elements.
In an electric radiator or room heater, state with reason, why the porcelain tube wound with a nichrome wire is placed between the pole and principal focus of the parabolic concave reflector.
State the position of heating element with respect to principal focus of concave reflector and give reason for choosing this position.
Two lamps are rated 220V, 50W and the other rated 220V, 100W are connected in series with the mains of 220 V. Explain, why the 50W lamp glows more?
State two advantages of filling an inert gas in an evacuated electric filament lamp.
An electric bulb is marked 100 W, 230 V. What does this mean?
What is the order of current drawn by appliances connected to the ‘light circuit’ of a household?
How is the amount of heat produced calculated due to the passage of current in a metallic conductor? Derive an expression for it.
An electric lamp A of 40 W and another electric lamp B of 100 W are connected to 220 V supply. Calculate the ratio of their filament resistances?
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 meaning of electric power of an electrical device? Write its SI unit.
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.
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.
