Chapter 11

NCERT
Class 10
Science
Solutions
14. Compare the power used in the 2 Ω resistor in each of the following circuits: (i) A 6 V battery in series with 1 Ω and 2 Ω resistors. (ii) A 4 V battery in parallel with 12 Ω and 2 Ω resistors.

Question:

Compare the power used in the 2 Ω resistor in each of the following circuits:

(i) A 6 V battery in series with 1 Ω and 2 Ω resistors

(ii) A 4 V battery in parallel with 12 Ω and 2 Ω resistors

Answer:

Ans.(i) When resistors are arranged in series

R = R1 + R2

R = 1 + 2

R = 3Ω

From Ohm’s law

I = V/R

I = 6/3

I = 2A

Power P1 = VI

P1 = 6 X 2

P1 = 12W

(ii) When resistors are arranged in parallel

R = R1R2/(R1+R2)

R = 12 X 2/(12 + 2)

R = 24/14

R = 7/3 A

P = VI

P2 = 4 X (7/3)

P2 = 28/3

P2 = 9.33W

P1/P2 = 12/9.33

⇒ P1 = P2 X 12/9.33

P1 = P2 X (12 X 100)/933

P1 = P2 X 1.3

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