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An electric heater is rated… (Class 10 Science 2026, Q34b)

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ScienceCBSE Class 10 · Board exam 2026, set 31/1/1 · 2 marks · Very short answer

CBSE Class 10 Science 2026: question 34(b)

Set in the CBSE Class 10 board exam of 2026, paper 31/1/1, section C, question 34(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q34(b) · 2 marks · Very short answerElectricity

An electric heater is rated 220 V; 11 A. Calculate the power consumed if the heater is operated at 200 V.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/1/1.

Hints

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

Hint 1

The heater's resistance does not change with the supply voltage. Find it first from the rating.

Hint 2

Use with 220 V and 11 A. Then use a power formula that contains only V and R, with the new voltage.

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.

  1. The rating tells us the heater draws at . By Ohm's law, its resistance is .

    ½ mark

  2. . The resistance stays the same when the heater is run at a different voltage.

    ½ mark

  3. When it is operated at , the power consumed is .

    ½ mark

  4. .

    ½ mark

Answer: R = 20 Ω; power consumed at 200 V = 2000 W (2 kW)

Where the marks are

  • Writes (½ mark)
  • Gets (½ mark)
  • Uses (½ mark)
  • Gets W (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Electricity, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 31/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.