Advertisements
Advertisements
Question
The resistance of filament of an electric heater is 500 Ω It is operated at 200V for 1 hour daily. Calculate the current drawn by the heater and the energy consumed in kWh, by the heater in a month of 30 days.
Advertisements
Solution
Given: R= 500 Ω, V = 200 volt.
Total time = t = 1 × 30h = 30h = 30 × 60 = 60 s = 108000s.
Current drawn by the heater I = `"V"/"R" = 200/500 = 0.4` A
The energy consumed (in kWh) =`("voltage" xx "Current")/100 xx "Time"`
`= (200 xx 0.4)/1000 xx 30` = 2.4 kWh.
RELATED QUESTIONS
The unit for expressing electric power is:
(a) volt
(b) joule
(c) coulomb
(d) watt
An electric kettle for use on a 230 V supply is rated 3000 W. For safe working, the cable connected to it should be able to carry at least:
(a) 2 A
(b) 5 A
(c) 10 A
(d) 15 A
1Kwh =`( 1 "volt "xx 1 am pere xx.............)/1000`
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 kettle is rated 2.5 kW, 250 V. Find the cost of running the kettle for two hours at Rs. 5.40 per unit.
A bulb with rating 250 V, 100 W is connected to a power supply of 220 V situated 10 m away using a copper wire of area of cross-section 5 mm2. How much power will be consumed by the connecting wires? Resistivity of copper = 1.7 × 10−8 Ωm
You are required to connect a bulb, a fan and a socket outlet to the mains in one set A and an air-conditioner and a refrigerator to the mains in other set B. Will you recommend the wire of same thickness and same insulation in both? explain your answer.
If a heater coil rated lkW, 220 V is connected in series with an electric bulb of 100 W, 220 V and are supplied 200V, power consumed by the bulb in this circuit is ______.
