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A metal rod of length 50 cm is… (Class 12 Physics 2025, Q6)

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PhysicsCBSE Class 12 · Board exam 2025, set 55/7/1 · 1 mark · MCQ

CBSE Class 12 Physics 2025: question 6

Set in the CBSE Class 12 board exam of 2025, paper 55/7/1, section A, question 6, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q6 · 1 mark · MCQElectromagnetic Induction

A metal rod of length 50 cm is held vertically and moved with a velocity of 10 m/s towards east. The horizontal component of the Earth's magnetic field at the place is 0·4 G. The emf induced across the ends of the rod is :

  1. (A)0·1 mV
  2. (B)0·2 mV
  3. (C)0·8 mV
  4. (D)1·6 mV

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 55/7/1.

Hints

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

Hint 1

Use the motional emf formula.

Hint 2

Convert gauss to tesla: T.

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. A vertical rod moving east cuts the horizontal (south–north) field, so .

    ½ mark

  2. ½ mark

Answer: 0.2 mV, option (B)

Where the marks are

  • Uses with T to get 0.2 mV (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Electromagnetic Induction, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 55/7/1: 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.