Where will the image of the candle be formed?

[kihr]

Homework Statement

A water tank is 4 meters deep. A candle flame is kept 6 metres above the level of the water. Mu for water is 4/3. Where will the image of the candle be formed?

Homework Equations

The Attempt at a Solution

I need a few clues to proceed. If I consider refraction at the water surface the image will be formed above the candle flame. The answer given in the book is 6 metres below the water level.

 

[tiny-tim]

Hi kihr!

A water tank is 4 meters deep. A candle flame is kept 6 metres above the level of the water. Mu for water is 4/3. Where will the image of the candle be formed?
…
The answer given in the book is 6 metres below the water level.

I think they must mean reflection, not refraction.

 

[ehild]

It depends on the position of the observer. An observer above the water sees the mirror image of the candle. An observer looking up would see the candle flame above the real one.

ehild

 

[kihr]

If we consider the surface of water as a mirror the answer is simple. But then what is the significance of giving the depth of the tank and the refractive index of water in this problem? This is what has confused me. Could you throw some light on this please?

 

[ehild]

I can not read the mind of other people. Maybe, there are more questions in your book, concerning the same set-up. Sometimes more data are given in a problem than necessary so as the student should choose which are relevant.

ehild

 

[kihr]

Thanks. I think the whole idea might have been to confuse the student!