19.1) (@) What is meant by 'electric power? Write the formula for electric power in
terms of potential difference and current.
(b) Calculate the cost of operating a heater of 500 W for 2 hours at the rate of Rs.
5 per unit.
II) The circuit diagram given below shows the combination of three resistors R1,
R2 and R3:
8Ω
7 Ω
R
R2
1222
R3
HHH
OV
1
(a) Find the total resistance of the circuit.
(b) Find the potential difference across Ry.
Answers
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0
Answer:
Pls explain
ima want to know
Answered by
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Answer:
(a) The rate at which electrical work is done or the rate at which electrical energy is consumed, is known as electric power.
It is given by
P=VI=watt
(b) Given : V=3V,I=0.5amp
(i) R=?
We know that V=IR
3=0.5R
R=6ohms
(ii) Power of lamp=VI
3×0.5
=1.5watt
(c) One kilowatt hour is the amount of electrical energy consumed when an electrical appliance having a power rating of 1 kilowatt is used for 1 hour.
1kWh=3.6×10
6
J
(d) Given P=500W=0.5kW,t=20hr
We know that
Energy consumed =P×t=0.5×20
=10kWh
Total cost =10× cost per unit
Therefore, total cost =10×3.9=Rs.39
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