CBSE Class 10 Science 2022 Outside Delhi Term II Set 1

Question : 13 of 15

Marks: +1, -0

An electric motor rated

1100\,\text{W}

is connected to

220\,\text{V}

mains. Find:

(i) The current drawn from the mains,

(ii) Electric energy consumed if the motor is used for

5

hours daily for

6

days.

(iii) Total cost of energy consumed if the rate of one unit is

\text{₹}\,5

Study the following circuit and find :

(i) Effective resistance of the circuit

(ii) Current drawn from the battery

(iii) Potential difference across the

5\,\Omega

resistor

Solution:

(i) Effective resistance of the circuit

R_3

and

R_4

are in series and both are parallel to

R_2

R_3+R_4=10\,\text{Ohm}

Effective Resistance across

R_2 (R')

\frac{1}{R'} = \frac{1}{R_2} + \frac{1}{R_3+R_4}

R' = 5\,\text{Ohm}

Now,

R_1, R'

and

R_5

are in series

Effective resistance of the circuit

= R_1+R'

+ R_5

= 5+5+10

= 20\,\text{Ohm}

(ii) Current drawn from battery

V = I R

I = \frac{V}{R}

I = \frac{20}{20}

I = 1\,\text{A}

(iii) Potential difference across 5-ohm resistor

V = I R

V = 1 \times 5

V = 5\,\text{V}

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