A concave miror is placed in water will there be any change in focal length? Give reason?

A concave mirror is held inside water.What would be the cahgne in the focal length of the mirror?

A concave lens is placed in contact with a convex lens of focal length 25 cm.The combination produces a real image at adistance of 80 cm, when an object is at a distance of 40 cm. What is the focallength of concave lens ?

A concave lens is placed in contact with a convvex lens of focal lenght 25 cm.the combinatin produces a real image at a distance of 80 cm,when the object is at a distance of 40 cm.What is the focal length of the concave lens?

A container is filled with water (mu= 1.33) upto a height of 33.25 cm .a concave miror is placed 15 cm above the water level and the image of an object placed at the bottom is formed 25 cm below the water leverl[Fig.2.90].Find the focal length of the concave mirror.

A glass (mu=1.5) convex lens of focl length 40 cm is placed in water (mu=1.3) .What will be its new focal length?