Two electric bulbs, B_1 and B_2, are connected in series to an A.C. supply of 200 V. The power ratings printed on the bulbs are: - B_1: 200 V, 60 W - B_2: 200 V, 100 W Using their rated voltage–power information, the ratio of their resistances R_1/R_2 is- (A) 5:3 (B) 3:5 (C) 3:4 (D) 4:3

PhysicsCBSE Class 12 · Sample paper, session 2026-27 · 1 mark · MCQ

CBSE Class 12 Physics sample paper 2026-27: question 10

From the official CBSE sample question paper for 2026-27, section A, question 10, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q10 · 1 mark · MCQCurrent Electricity

Two electric bulbs, $B_{1}$ and $B_{2}$ , are connected in series to an A.C. supply of 200 V. The power ratings printed on the bulbs are:

$B_{1}$ : 200 V, 60 W
$B_{2}$ : 200 V, 100 W

Using their rated voltage–power information, the ratio of their resistances $R_{1} / R_{2}$ is-

(A)5:3
(B)3:5
(C)3:4
(D)4:3

Figure in the paper: Series circuit of two bulbs B1 and B2 connected to a 200 V A.C. source; voltage drops V1 across B1 and V2 across B2 marked. See it in the official paper.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

Open one hint at a time and try again before the next.

Hint 1

Express resistance in terms of the rated voltage and power.

Hint 2

With equal $V$ , $R$ is inversely proportional to $P$ .

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

From the ratings, $R = \frac{V ^{2}}{P}$ , and both bulbs have the same rated voltage.
½ mark
So $\frac{R _{1}}{R _{2}} = \frac{P _{2}}{P _{1}} = \frac{100}{60} = \frac{5}{3}$ , i.e. 5:3. Option (A).
½ mark

Answer: 5:3, option (A)

Where the marks are

Uses $R = V^{2} / P$ to get the ratio 5:3 (1 mark)

Revise the chapter

Chapter: Current Electricity (notes, formulas, where marks are lost and every past question)

Practise this chapterBoard-style questions from Current Electricity, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2026-27: every question, by section.

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CBSE Class 12 Physics sample paper 2026-27: question 10

Hints

Step-by-step solution

Revise the chapter

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