Skip to content

The electrical resistivity of… (Class 10 Science 2025, Q32)

questionbuddy.in/q/cbse-10-science-2025-31-4-1-q32-electrical-resistivity-materials-material-resistivity

ScienceCBSE Class 10 · Board exam 2025, set 31/4/1 · 3 marks · Short answer

CBSE Class 10 Science 2025: question 32

Set in the CBSE Class 10 board exam of 2025, paper 31/4/1, section C, question 32, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q32 · 3 marks · Short answerCompetency-basedElectricity

The electrical resistivity of three materials A, B and C at 20°C is given below :

MaterialResistivity (Ω m)
A
B
C
  1. (i)

    Classify these materials as conductor, alloy and insulator.

    0 marks
  2. (ii)

    Give one example of each of these materials and state one use of each material in the design of an electrical appliance say an electric stove or an electric iron.

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/4/1.

Hints

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

Hint 1

Lower resistivity means the material conducts better.

Hint 2

Think of an electric iron: which part must get hot, which carries current easily, and which part you hold?

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) A ( Ω m, extremely high resistivity) is an insulator.

    ½ mark

  2. (i) B ( Ω m, moderately high) is an alloy.

    ½ mark

  3. (i) C ( Ω m, very low) is a conductor.

    ½ mark

  4. (ii) A, insulator: plastic or rubber, used for the handle of an electric iron or the feet of an electric stove.

    ½ mark

  5. (ii) B, alloy: nichrome, used as the heating element of an electric iron or stove.

    ½ mark

  6. (ii) C, conductor: copper, used for the connecting wires and cord of the appliance.

    ½ mark

Answer: (i) A insulator, B alloy, C conductor; (ii) plastic for the iron handle, nichrome for the heating element, copper for the connecting wires.

Where the marks are

  • Correct classification of A, B and C (½ mark each)
  • Correct example with its use for each material (½ mark each)

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 paper2025 board paper, set 31/4/1: 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.