CBSE Class 10 Science 2022 · Paper 31/3/3 · Question 14

Electricity 4 marks Medium

Study the following electric circuit in which the resistors are arranged in three arms A, B and C :

(a)Find the equivalent resistance of arm C.[1]
(b)Calculate the equivalent resistance of the parallel combination of the arms B and C.[1]
(c)(i)Determine the current that flows through the ammeter.[2]
(c)(ii)OR : Determine the current that flows in the ammeter when the arm B is withdrawn from the circuit.[2]

Answer

(a)

R_{C} = 10 + 20 + 30 = 60 Ω

. (b)

R_{B} = 5 + 10 + 15 = 30 Ω

and

\frac{1}{R _{B C}} = \frac{1}{30} + \frac{1}{60} = \frac{1}{20}

, so

R_{B C} = 20 Ω

. (c)(i)

R_{A} = 5 + 15 + 20 = 40 Ω

, so the total resistance is

40 + 20 = 60 Ω

and the current through the ammeter is

I = \frac{6}{60} = 0.1

A. OR (c)(ii) With arm B withdrawn, the total resistance is

R_{A} + R_{C} = 40 + 60 = 100 Ω

, so the ammeter current is

I = \frac{6}{100} = 0.06

🔒 Step-by-step solution