Skip to content

Answer the following. (Class 12 Physics 2024, Q26)

questionbuddy.in/q/cbse-12-physics-2024-55-5-1-q26

PhysicsCBSE Class 12 · Board exam 2024, set 55/5/1 · 3 marks · Short answer

CBSE Class 12 Physics 2024: question 26

Set in the CBSE Class 12 board exam of 2024, paper 55/5/1, section C, question 26, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q26 · 3 marks · Short answerElectromagnetic Waves

Answer the following.

  1. (a)

    Name the parts of the electromagnetic spectrum which are (i) also known as 'heat waves' and (ii) absorbed by ozone layer in the atmosphere.

    0 marks
  2. (b)

    Write briefly one method each, of the production and detection of these radiations.

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 55/5/1.

Hints

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

Hint 1

Which radiation from a heater warms your skin?

Hint 2

Ozone protects us from radiation just beyond violet.

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)(i) Heat waves are infrared waves.

    ½ mark

  2. (a)(ii) Radiation absorbed by the ozone layer is ultraviolet rays.

    ½ mark

  3. (b) Production of infrared: emitted by hot bodies, through vibrations of atoms and molecules (e.g. a heated filament or a room heater).

    ½ mark

  4. Production of ultraviolet: emitted by very hot bodies such as the sun, and by special UV lamps (e.g. mercury vapour lamps).

    ½ mark

  5. Detection of infrared: thermopile, bolometer or infrared photographic film.

    ½ mark

  6. Detection of ultraviolet: photocells or photographic film.

    ½ mark

Answer: (i) Infrared; (ii) Ultraviolet. IR: produced by hot bodies, detected by thermopile/bolometer. UV: produced by the sun or UV lamps, detected by photocells/photographic film.

Where the marks are

  • Infrared as heat waves (½ mark)
  • Ultraviolet absorbed by ozone (½ mark)
  • Production of IR (½ mark)
  • Production of UV (½ mark)
  • Detection of IR (½ mark)
  • Detection of UV (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Electromagnetic Waves, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 55/5/1: 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.