Q

# Give answer! A point source of light, S is placed at a distance L in front of the centre of plane mirror of width d which is hanging vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror., at a distance 2L as shown b

A point source of light, S is placed at a distance L in front of the centre of plane mirror of width d which is hanging vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror., at a distance 2L as shown below . The distance over which the man can see the image of the light source in the mirror is :

• Option 1)

3d

• Option 2)

d

• Option 3)

$\frac{d}{2}$

• Option 4)

2d

Views

Image formation from plane mirror -

1)    Distance of object from mirror = Distance of image from the mirror.

2)    Line joining a point object and its image is normal to the reflecting surface

3)    Size of image is same as that of the object.

4)    For real object the image is virtual and for a virtual object the image is real.

-

This question can be easily solved with help of Geometry

$tan\theta =\frac{\frac{d}{2}}{L}=\frac{x}{3L}$

So  $x=\frac{3d}{2}$

So  $y=2x=\frac{3d}{2}\times 2=3d$

$y=3d$

Option 1)

3d

Option 2)

d

Option 3)

$\frac{d}{2}$

Option 4)

2d

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