Advertisements
Advertisements
Question
A 2 kWh heater, a 200 W TV and three 100 W lamps are all switched on from 6 p.m. to 10 p.m. What is the total cost at Rs 5.50 per kWh?
Advertisements
Solution
Energy consumed by the TV in 1 hour, E1 = P x t = 200 W x 1 hour = 200 Wh = 0.2 kWh
Energy consumed by the three bulbs in 1 hour, E2 = 3 x P x t = 3 x 100 W x 1 hour = 300 Wh = 0.3 kWh
Energy consumed by the heater in 1 hour, E3 = 2 kWh
Total energy consumed, E = E1+ E2 + E3
= 0.2 kWh + 0.3 kWh + 2 kWh
= 2.5 kWh
Total energy, consumed from 6 p.m. to 10 p.m., E = 4 x 2.5 kW = 10 kWh
Total cost at base price, Rs. 5.5 per kWh = E x 5.5 = 10 x 5.5 = Rs. 55 Energy consumed by the TV in 1 hour, E1 = P x t = 200 W x 1 hour = 200 Wh = 0.2 kWh
Energy consumed by the three bulbs in 1 hour, E2 = 3 x P x t = 3 x 100 W x 1 hour = 300 Wh = 0.3 kWh
Energy consumed by the heater in 1 hour, E3 = 2 kWh
Total energy consumed, E = E1+ E2 + E3
= 0.2 kWh + 0.3 kWh + 2 kWh
= 2.5 kWh
Total energy, consumed from 6 p.m. to 10 p.m., E = 4 x 2.5 kW = 10 kWh
Total cost at base price, Rs. 5.5 per kWh = E x 5.5 = 10 x 5.5 = Rs. 55
APPEARS IN
RELATED QUESTIONS
Define watt-hour. How many joules are equal to 1 watt-hour?
A bulb of 40 W is used for 12.5 h each day for 30 days. Calculate the electrical energy consumed.
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
What is wrong with the circuit diagram (Fig. 34)? Carefully check the symbols and assign proper positive and negative signs to them.
Two resistors A and B of 4 Ω and 6 Ω respectively are connected in parallel. The combination is connected across a 6 volt battery of negligible resistance. Calculate the power supplied by the battery.
An electric iron rated 750 W is operated for 2 hours/day. How much energy is consumed by the electric iron for 30 days?
Which cable, one rated 15A and the other rated 5A will be thicker? Give a reason.
Point out two main disadvantages of ‘Tree System’.
Name three main characteristics of an heating element.
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?
What is ‘Rating’ of an electric appliance?
How does the heat produced by die passage of current in a metallic wire depend on the current in the wire?
State the reason why, in a three pin plug, the earth pin is longer and thicker than the other two.
Three 250 W heaters are connected in parallel to a 100 V supply, Calculate the energy supply in kWh to the three heaters in 5 hour.
An Electric bulb is marked 100 W, 230 V. What how long would this lamp take to consume one unit of electricity?
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 ______.
