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For a metallic conductor, the… (Class 12 Physics 2023, Q2)

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PhysicsCBSE Class 12 · Board exam 2023, set 55/1/1 · 1 mark · MCQ

CBSE Class 12 Physics 2023: question 2

Set in the CBSE Class 12 board exam of 2023, paper 55/1/1, section A, question 2, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q2 · 1 mark · MCQCurrent Electricity

For a metallic conductor, the correct representation of variation of resistance R with temperature T is :

  1. (A)Graph: R vs Temp., straight line rising with positive intercept on R axis
  2. (B)Graph: R vs Temp., straight line rising from origin
  3. (C)Graph: R vs Temp., decreasing curve (convex) from high R
  4. (D)Graph: R vs Temp., curve rising from origin with increasing steepness

Figure in the paper: Four resistance (R) versus temperature (T) graphs (a)-(d) as described in the options. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 55/1/1.

Hints

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

Hint 1

Does the resistance of a metal increase or decrease with temperature?

Hint 2

Over a wide temperature range the variation is not exactly linear.

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. For a metal, holds only over a limited range. Over a wide range the resistance rises non-linearly, more and more steeply, as collisions of electrons with the vibrating ions increase.

    ½ mark

  2. A curve rising with increasing steepness matches this behaviour, so the answer is option (D).

    ½ mark

Answer: Option (D)

Where the marks are

  • Identifies the non-linearly increasing R–T curve (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Current Electricity, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 55/1/1: 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.