Question

2. The angle between an incident ray and the plane mirror is 30. The total angle between the incident ray and the reflected ray will be? a) 30 b) 60 c) 90 d) 120​

Answer 1

Answer:

30 (a) option

Explanation:

Hope it's help you

Answer 2

Answer:

Option D (120°)

Explanation:

As per the provided information in the given question, we have :

• Angle b/w an incident ray and plane mirror = 30°

We are asked to calculate the angle between incident ray and reflected ray. Take a look at the attachment! Clearly, the angle between reflected ray and the incident ray is,

$\longrightarrow \tt { \angle i + \angle r }$

Also, according to 2nd law of reflection,$\tt { \angle i = \angle r }$ since, angle of incidence and angle of reflection are always equal.

Now, as we know that, normal is the perpendicular line to the point of incidence. So,

$\longrightarrow \tt { \angle COE = 90^\circ }$

$\longrightarrow \tt { \angle COA + \angle AOE = 90^\circ }$

$\tt \angle COA$ is the angle between plane mirror and incident ray. Here, its value is 30°. Given in the question.

$\longrightarrow \tt { 30^\circ + \angle i = 90^\circ }$

$\longrightarrow \tt { \angle i = 90^\circ - 30^\circ }$

$\longrightarrow \tt { \angle i = 60^\circ \dots (1)}$

As we know that,

$\longrightarrow \tt { \angle r = \angle i }$

$\longrightarrow \tt { \angle r = 60^\circ \dots (2) }$

Now, according the figure,

The angle between reflected ray and the incident ray is,

$\longrightarrow \tt { \angle i + \angle r }$

$\longrightarrow \tt { 60^\circ + 60^\circ }$

$\longrightarrow \underline{\boxed{ \tt {120^\circ }}} \; \red{\bigstar}$

Therefore, the total angle between the incident ray and the reflected ray will be 120°.

Option D is correct.