What will happen to the focal length of a concave mirror, convex mirror, concave lens and convex lens when immersed in water? will it change ? if yes explain .
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In case of spherical mirrors (both concave and convex), there will be no change in the focal length of the mirrors when immersed in water. This is because the focal length of mirrors does not depend on the external medium in which it is held.
In case of lenses, refraction takes place. When a lens is immersed in water, the value of refractive index decreases. Hence its focal length increases.