CBSE 12th Term-2 2022 : Physics Important 2 Marks Questions With Answers

In this post CBSE 12th Term Physics Important 2 Marks Questions with Solutions are given. CBSE will conduct Term 2 Physics Board Exam for class 12th on 20th May 2022. Check here for 2 marks questions given below to solve before going for your CBSE Class 12th Term 2 exam.

CBSE Class 12 Term 2 Study Material
CBSE Class 12 Reduced Syllabus for Term 2 Exam 2022	CBSE Class 12 Sample Paper for Term 2 Exam 2022
CBSE Class 12 Previous Year Question Paper with Solutions	CBSE Class 12 Term 2 Full Study Material 2022
CBSE Revision Notes For Class 12	CBSE Class 12 Topper Answer Sheet

1. Write any four properties of EM waves.

Answer : (1) They are transverse in nature.

(2) They are produced by accelerated charges.

(3) In an electromagnetic wave, Electric vector E and B magnetic fields oscillate sinusoidally in space and time The oscillating vector E and B are perpendicular to each other, and to the direction of propagation.

(4) The oscillations of vector E and B are in same phase.

2. Give one use of each of the following

Infrared rays.
Gamma rays.
Microwaves.
UV radiations.

Answer : (i) Infrared rays: It is used for fog or haze photography.

(ii) Gamma rays: If is used in medical treatment.

(iii) Micro-waves: If is used in radio and tele communication.

(iv) Ultraviolet radiations: If is used in sterilization of water.

3. Draw a diagram showing the propagation of EM waves along the x-direction, indicating clearly the directions of electric and magnetic fields associated with it.

Answer :

4. Find the wavelength of em waves of frequency 4 x 10⁹ Hz in free space. Give its two applications.

Answer :

This wavelength corresponds to microwave region (or short radio waves).

These are used in (i) RADAR (ii) Microwave ovens.

5. Identify the following electromagnetic radiations as per the frequencies given below :

(a) 10²⁰ Hz

(b) 10⁹ Hz

Give one application of each.

Answer :

6. Let the wavelengths of the electromagnetic waves be used quite often for
(i) killing germs in household water purifiers
(ii) remote sensing
(iii) treatment of cancer, be labeled as λ₁, λ_2, and λ₃ in increasing order.

Answer : (i) UV radiation (λ₁)

(ii) Microwaves (λ₂)

(iii) γ-rays (λ₃) The increasing order of wavelength is λ₃ < λ₁ < λ₂.

7. Give two reasons to explain why a reflecting telescope is preferred over a refracting telescope.

Answer : The reflecting telescopes are preferred over refracting type because of the following reasons:

(i) There is no chromatic aberration in case of reflecting telescopes as the objective is a mirror.

(ii) Spherical aberration is reduced in case of reflecting telescopes by using mirror objective in the form of a paraboloid.

8. Calculate the speed of light in a medium whose critical angle is 45°. Does the critical angle for a given pair of media depend on the wavelength of incident light? Give a reason for your answer.

Answer : Using the snell's law we have

μ = 1/sin C.....(1)

where, C is the critical angle of the medium and μ is the refractive index of the medium.

Also, μ = c/v.........(2)

Now, from equations (1) and (2), we have

This is the speed of the light in the medium.

Refractive index of a medium is inversely proportional to the wavelength of light. So, critical angle also depends upon the wavelength of incident light.

9. How does the fringe width, in young’s double-slit experiment, change when the distance of separation between the slits and screen is doubled?

Answer : The fringe width is

β = λD/d

If D (distance between slits and screen) is doubled, then fringe width will be doubled.