Question

A man standing at a position X in front of a plane mirror, a distance of y metre from the mirror as shown in figure. When the man moves 5 m away from the mirror, the new distance between the man and his image becomes 20 metre. What is the value of y?

(A) 5 m 

(B)10 m 

(C) 20 m 

(D) 40 m

Answer 1

Correct option (A) 5 m   

Explanation:

 New distance between the man and the mirror = y+5

 ∴ The distance between the man and his image

(y+5)x 2 =20 

2y +10=20

2y =10 

y= 5 m