CBSE Class 10 Science 2019 · Paper 31/4/1 · Question 19(b)

Electricity 5 marks Medium

(a)How will you infer with the help of an experiment that the same current flows through every part of the circuit containing three resistors $R_{1}$ , $R_{2}$ and $R_{3}$ in series connected to a battery of $V$ volts ?
(b)Study the following circuit and find out : (i) Current in $12 Ω$ resistor. (ii) Difference in the readings of $A_{1}$ and $A_{2}$ , if any.

Answer

The ammeter reads the same everywhere in a series circuit; the $12 Ω$ resistor carries 0.25 A and $A_{1}$ , $A_{2}$ read alike.

(a) Connect the three resistors

R_{1}

R_{2}

and

R_{3}

in series with a battery of

V

volts, an ammeter and a plug key. Plug the key and note the ammeter reading. Then place the ammeter in turn between

R_{1}

and

R_{2}

, between

R_{2}

and

R_{3}

, and after

R_{3}

, noting the reading each time. The ammeter shows the same reading in every position, so the same current flows through every part of the series circuit. (b) The two

24 Ω

resistors are in parallel:

\frac{1}{R _{p}} = \frac{1}{24} + \frac{1}{24} = \frac{1}{12}

, so

R_{p} = 12 Ω

. Total resistance

R = 12 Ω + 12 Ω = 24 Ω

, and the circuit current

I = \frac{V}{R} = \frac{6}{24} = 0.25

A. (i) The current in the

12 Ω

resistor is

0.25

A, the whole circuit current. (ii) There is no difference:

A_{1}

and

A_{2}

are both in series in the main circuit, so both read

0.25

🔒 Step-by-step solution

CBSE Class 10 Science 2019 · Paper 31/4/1 · Question 19(b)

Answer

From the board papers

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