Question

A ray of light makes an angle of 50° with the surface S1 of the glass slab.Its angle of incidence will be____.
a)50°
b)40°
c)140°
d)0°​

Answer 1

Definition: The angle of incidence is defined as the angle made by the incident ray with the normal to the point of incidence.

This is an example of an ill-framed question which creates confusion in the mind of the students.

So in case if the question means that “the incident ray of light makes an angle of 50 degrees with the glass slab” then we get the following situation and the angle of incidence will be 90∘−50∘=40∘:

OR

In case if the question means that “the incident ray of light makes an angle of 50 degrees with the normal” then we get the following situation and the angle of incidence will be  50∘:

Answer 2

Hi friend here is your answer

_________________________________

The ray make an angle of 50 degree with the surface as shown in the attached pic

We know that the angle of incidence is equal to the angle of refraction

There is a linear pair as shown in diagram

Hence

50 + i + r + 50 = 180

100 + i + r = 180

But i = r

Hence

2i = 180-100

i = 40 degree

___________________________________

Hope it helps you............!!

#TheUsos

Down Since

Day One Ish