ফোকাল দৈর্ঘ্য `f` (বাতাসে) একটি অবতল আয়না জলে নিমজ্জিত হয় `(mu=4/3)`। ফোকাল দৈর্ঘ্য

A convex mirror of focal length f (in air) is immersed in water (mu = 4/3) . The focal length of the mirror in water will be -

A concave mirror of focal length f (in air) is immersed in water (mu=4//3) . The focal length of the mirror in water will be

Assertion : A double convex lens (mu=1.5) has focal length 10 cm . When the lens is immersed in water (mu=4//3) its focal length becomes 40 cm . Reason : (1)/(f)=(mu_(1)-mu_(m))/(mu_(m))((1)/(R_(1))-(1)/(R_(2)))

If velocity of bird (B) in downward direction with respect to surface (water and air) is 3m/s. Then what is the velocity of bird (B) with respect to fish (F) ? (._(a)mu_(w) = (4)/(3))

Two identical glass (mu_(g)=3//2) equiconvex lenses of focal length f are kept ini contact. The space between the two lenses is filled with water (mu_(w)=4//3) . The focal length of the combination is

Two identical glass (mu_(g)=3//2) equiconvex lenses of focal length f are kept in contact. The space between the two lenses is filled with water (mu_(w)=4//3) . The focal length of the combination is