Question

How much the object-image distance change, if a plane mirror is shifted 0.4m away from object?

• A. 0.4 m
• B. 0.8 m
• C. 0 m
• D. 0.5 m

Answer 1

The correct option is B 0.8 m

Let us assume, initially the object is at a distance of "x" metres from the mirror.
Thus, the object-image distance = (x+x) = 2x metres.
The mirror is shifted 0.4 metre away from the object.
We know that, in the case of a plane mirror, the distance between the object and the mirror is equal to the distance between the mirror and the image.
Therefore, the new distance between the object and its image
=(x + 0.4 + x + 0.4) m
=(2x + 0.8) m
Now, the change in the object-image distance = [(2x + 0.8) - (2x)] m
= 0.8 m