Question

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.

Answer 1

Answer:

Pls explain

ima want to know

Answer 2

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