JEE Main · 2023 · 10 Apr 2023 · Shift 1 · Geometrical Optics

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An object is placed at a distance of 12 cm in front of a plane mirror. The virtual and erect image is formed by the mirror. Now the mirror is moved by 4 cm towards the stationary object. The distance by which the position of image would be shifted, will be:

(A)4 cm towards mirror
(B)8 cm towards mirror✓ Correct
(C)8 cm away from mirror
(D)2 cm towards mirror

Answer: (B)

Solution

For a plane mirror the image lies as far behind the mirror as the object is in front. With the object

12

cm away the image is

12

cm behind the mirror. Moving the mirror

4

cm towards the object makes the object distance

8

cm, so the image is now

8

cm behind the mirror. The image advances by twice the mirror's displacement,

2 \times 4 = 8

cm. The image shifts

8

cm towards the mirror.

JEE Main · 2023 · 10 Apr 2023 · Shift 1 · Single correct option

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