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(i) Define electric power… (Class 10 Science 2024, Q36A)

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ScienceCBSE Class 10 · Board exam 2024, set 31/1/1 · 5 marks · Long answer

CBSE Class 10 Science 2024: question 36(A)

Set in the CBSE Class 10 board exam of 2024, paper 31/1/1, section D, question 36(A), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q36(A) · 5 marks · Long answerElectricity

(i) Define electric power. Express it in terms of potential difference (V) and resistance (R).
(ii) An electric oven is designed to work on the mains voltage of 220 V. This oven consumes 11 units of electrical energy in 5 hours. Calculate :
(a) power rating of the oven
(b) current drawn by the oven
(c) resistance of the oven when it is red hot

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/1/1.

Hints

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

Hint 1

Power is energy per unit time; combine with Ohm's law.

Hint 2

1 unit of electrical energy = 1 kWh, so divide the units by the hours to get kW.

Hint 3

Once you have P, use and .

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. (i) Electric power is the rate at which electrical energy is consumed or dissipated in a circuit, i.e. .

    1 mark

  2. Since and, by Ohm's law, , we get .

    1 mark

  3. (ii)(a) Energy consumed units kWh and time h.
    .

    1 mark

  4. (b) .

    1 mark

  5. (c) . (Check: .)

    1 mark

Answer: (i) Rate of consumption of electrical energy; . (ii)(a) 2200 W (2.2 kW); (b) 10 A; (c) 22 Ω

Where the marks are

  • Correct definition of electric power (1 mark)
  • Expression (1 mark)
  • Power = 11 kWh / 5 h = 2.2 kW = 2200 W (1 mark)
  • Current A (1 mark)
  • Resistance (1 mark)

Revise the chapter

  • Chapter: Electricity (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Electricity, one at a time, marked against the answer key and marking points.Back to the full paper2024 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.