If a plane mirror is rotated by an angle Q, by how much will the angle between the incident and reflected ray change?

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

answer is B.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

If a plane mirror is rotated by an angle Q, 2Q will be the angle change between the incident and reflected ray.
On rotating the mirror by angle Q, the angle of incidence changes from

i

i + Q

. Initially, the angle between the incident ray and reflected ray =

i_{1} + r_{1} = i_{1} + i_{1} = 2 i_{1}

After rotation of mirror:- Angle between the same incident ray and rotated reflected ray

= i_{2} + {r ​}_{2} = i_{2} + i_{2} = 2 i_{2} ​

(since

i = r

) therefore,

2 i_{2} = 2 (i_{1} + Q) = 2 i_{1} + 2 Q

Hence, reflected ray is rotated by angle

= (2 i_{1} + 2 Q - 2 i_{1}) = 2 Q

Watch 3-min video & get full concept clarity

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Books for IIT JEE

Best Books for NEET

How to Join IIT after 10th

🔥 Start Your JEE/NEET Prep at Just ₹1999 / month - Limited Offer! Check Now!

Get Expert Academic Guidance – Connect with a Counselor Today!

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Books for IIT JEE

Best Books for NEET

How to Join IIT after 10th