Question

Does focal length of a spherical mirror changes when it is completely immersed in the water ? Predict and write the reason

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Answer 1

$\huge{\mathcal{\purple{A}\green{N}\pink{S}\blue{W}\purple{E}\green{R}\pink{!}}}$

Mirrors, spherical or otherwise, operate on the principle that the angle of reflection of a ray of light equals the angle at which it strikes the mirror's surface. That behavior is not affected by the medium in which the light travels, so the mirror's focal length would be no different in air or water. 

If you had asked about the focal length of a LENS, however, the answer would be different. Lenses work by REFRACTION, not reflection, and the angle of refraction is based on the difference between the speed of light in the lens compared to the surrounding medium. When immersed in water, the difference between light's speed in the lens and the surrounding medium is less than the difference when it's in air, and the focal length of a lens would be greater under water. 

Answer 2

Answer:

Remain unchanged

Explanation :

Focal length is the property of the spherical mirror. So, it does not changes when immersed in water .

There will be no change in mirrors focal length which is going to be immersed in water. In the spherical mirrors, the focal length will depend on the external medium to be held.

In this process, the refraction will take place when the lens is placed in water. Therefore the value of the refractive index will be decreased. So the focal length increases. It is also independent of water immersion.