A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle θ, the spot of the light is found to move through a distance y on the scale. The angle θ is given by :

Question

A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle θ, the spot of the light is found to move through a distance y on the scale. The angle θ is given by : (A) (y/x) (B) (x/2y) (C) (x/y) (D) (y/2x)

Tardigrade Admin · Accepted Answer

When mirror is rotated by θ angle reflected ray will be rotated by 2 A. <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/37ba21024880fe0a1c11222e6c7032ae-.png" /> (y/x)=2 θ θ=(y/2 x)

$\frac{y}{x}$

$\frac{x}{2 y}$

$\frac{x}{y}$

$\frac{y}{2 x}$

When mirror is rotated by $θ$ angle reflected ray will be rotated by $2 A$ .

$\frac{y}{x} = 2 θ$
$θ = \frac{y}{2 x}$

xy​

2yx​

yx​

2xy​

When mirror is rotated by θ angle reflected ray will be rotated by 2A. xy​=2θ θ=2xy​

$\frac{y}{x}$

$\frac{x}{2 y}$

$\frac{x}{y}$

$\frac{y}{2 x}$

When mirror is rotated by $θ$ angle reflected ray will be rotated by $2 A$ .

$\frac{y}{x} = 2 θ$
$θ = \frac{y}{2 x}$