An engineer intends to deviate a light ray from its path by 120^o through reflection from a plane mirror. Calculate the angle of incidence

Award0001

2 years ago

This is a question from deviation in plane mirror (single inclination)

During deviation
incident angle , reflected angle and angle of deviation are arranged In such a way that
I° + r° + D = 180( sum of angles on a straight line)

But from 2nd law of reflection, i° = r° (with respect from the normal)

Therefore
i° + r° + D = 180 becomes
i° + i° + D = 180
2i° + D = 180
D = 180 - 2i°

From the question
D = 120
I° = ?
12o = 180- 2i°
2i° = 180 -120
2i° = 60
i° = 60/30 = 20°🌟🤝

ibrahimdzakwandirmbita

4 years ago

Using
d=2g
Where d is angle of deviation and g is glancing angle
> d= 2g
120=2g
g=120/2
g=60
There fore
i+g=90
i+60=90
I=90-60
I=30⁰