Question

if two plane mirrors are inclined at an angle theta with horizontal as shown in figure. if a ray incident from 10 degree above horizontal becomes vertical after reflection from this mirror. find theta
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Answer 1

To Find:-

• value of θ.

Solution:-

If the inclination of the plane mirror is θ, then the reflected ray must be r the n.

we know that,

→ r + θ = 90.

Angle of incidence will be i then as given in the question the ray is incident from 10 degree above horizon hence, 10 + i + i = 90.

Now,

i will be 40 on solving, then as the reflected ray will be perpendicular.

Hence,

→ r + 40 = 90 then r = 50.

→ θ = 40°

Answer 2

To Find:-

value of θ.

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Solution:-

If the inclination of the plane mirror is θ, then the reflected ray must be r the n.

we know that,

→ r + θ = 90.

Angle of incidence will be i then as given in the question the ray is incident from 10 degree above horizon hence, 10 + i + i = 90.

Now,

i will be 40 on solving, then as the reflected ray will be perpendicular.

Hence,

→ r + 40 = 90 then r = 50.

→ θ = 40°