Question

David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be

(i) 3 m

(ii) 5 m

(iii) 6 m

(iv) 8 m

Answer 1

(iii) 6 m

In the case of a plane mirror, the distance between the object and the mirror (d₁) is same as the distance between the image and the mirror (d₂).

Given,

Distance between the mirror and David’s image, d₂ = 4 m

Therefore, d₁ = d₂ = 4 m

If David moves 1 m towards the mirror, then d₁ = 4 − 1 = 3 m

Again, d₁ = d₂ = 3 m

Therefore, the distance between David and his image is d₁ + d₂ = 3 + 3 = 6 m.