Question

A magician during a show makes a glass lens with n= 1.47 disappear in a trough of liquid . what is the refractive index of the liquid ? could the liquid be water ? ​

Answer 1

Question:

A magician during a show makes a glass lens with n=1.47 disappear in a trough of liquid. What is the refractive index of the liquid? Could the liquid be water?

Answer:

The refractive index of the liquid should be 1.47; only then we have not any refraction and light direction change.

It can not be water because:

If $\mu_1=\mu_2$

Then $f=\infty$

Hence the lens in the liquid will act like a plane sheet , when refractive index of the lens and the surrounding medium is the same.

Therefore $\mu_1=\mu2=1.5$

Hence the liquid medium is not water, Refractive index for water = 1.33

It can be glycerine or turpentine as both are "clear" liquid with refractive index equal to 1.47.

Answer 2

Given,

A magician during a show makes a glass lens with n= 1.47 disappear in a trough of liquid

To find,

Refractive index for the liquid

Could the liquid be watered

Solution,

A magician during a show makes a glass lens with n= 1.47 disappear in a trough of liquid

To make the lens disappear, the liquid's refractive index must be equal to 1.47. This means that n1=n2. 1/f=0or f -infinity is the result of this. The liquid lens will behave like a flat sheet of glass.

No, the liquid is not water, to be sure. Glycerine could be the answer.