Question

A plane mirror is held at a height h above the bottom of an empty beaker. The beaker is now filled with water upto a depth d. The general expression for the distance from a scratch at the bottom of the beaker to its image in terms of h and the depth d of water in the beaker is –

• A. 2h – d $\left( \frac { \mu } { \mu - 1 } \right)$
• B. 2h – $\frac { \mathrm { d } } { 2 }$ $\left( \frac { \mu - 1 } { \mu } \right)$
• C. 2h – d $\left( \frac { \mu - 1 } { \mu } \right)$
• D. 2h – d $\left( \frac { 2 \mu - 1 } { \mu } \right)$

Answer 1

Answer: (C)

2h – d $\left( \frac { \mu - 1 } { \mu } \right)$

Answer 2

If the water is filled through depth 'd' & scratch is at the bottom then the apparent depth of scratch is given by d_app= $\frac { \mathrm { d } _ { \text {real } } } { \mu }$ and now the final image of this new image behaving like an object through the plane mirror is formed at equal distance behind the mirror.