Target Exam

CUET

Subject

Physics

Chapter

Ray Optics

Question:

An object moving towards mirror as shown in the figure.

A. the speed of image will be 2 m/s irrespective the speed of mirror.
B. the speed of image will be 2 m/s only when speed of mirror is zero.
C. the speed of image will be 6 m/s when mirror is moving towards object with 2 m/s.
D. the speed of image will be 6 m/s, where mirror is moving away from object with 2 m/s.
E. the speed of image will be 2 m/s, where mirror is moving away from object with 2 m/s.

Choose the correct answer from the options given below:

Options:

A, B only

B, C only

B, C, D only

B, C, E only

Correct Answer:

B, C, E only

Explanation:

The correct answer is Option (4) → B, C, E only

Use the relation for velocity of image in a plane mirror:

$v_I = 2v_M - v_O$

Take right direction as positive.

Object is moving towards mirror $\rightarrow v_O = +2 \text{ m/s}$

A: Image speed always 2 m/s: Depends on mirror motion $\rightarrow$ . Incorrect

B: Mirror at rest $v_M = 0$

$v_I = 2(0) - 2 = -2$

Speed = $2 \text{ m/s}$ Correct

C: Mirror moving towards object $v_M = -2$

$v_I = 2(-2) - 2 = -6$

Speed = $6 \text{ m/s}$ Correct

D: Mirror moving away $v_M = +2$

$v_I = 2(2) - 2 = 2$

Speed = $2 \text{ m/s}$ (not 6)

E: Mirror moving away $v_M = +2$

$v_I = 2$

Speed = $2 \text{ m/s}$ Correct