Fill in the blank spaces with appropriate answers:
A double convex lens of focal length 'f' is cut at `90^@` to its principal axis into two identical component lenses. Then each component lens is a _________ lens.

Fill in the blank spaces with appropriate answers: A double convex lens of focal length 'f' is cut at 90^@ to its principal axis into two identical component lenses. The focal length of each component lens is _________.

Fill in the blank spaces with appropriate answers: A double convex lens of focal length 'f' is cut at 90^@ to its principal axis into two identical component lenses. If D_1 and D_2 are the respective powers then D_2 is _____ than D_1

Fill in the blank spaces with appropriate answers: A double convex air bubble in water behaves as a ______ lens.

If the lens is double concave then its focal length is

Fill in the blank spaces with appropriate answers: The focal length of a divergent lens is 40 cm. The power of the lens is ___ Diopter.

Fill in the blank spaces with appropriate answers: A convex mirror of focal length 'f' produces an image (1/n) of the size of the object. The object distance is ________.

Fill in the blank spaces with appropriate answers: A concave mirror of focal length 'f' produces a real image of size n-times that of the object. The object distance is _________.

Fill in the blank spaces with appropriate answers: A concave mirror of focal length 'f' produces a virtual image of size n-times that of the object. The object distance is ________.

Fill in the blank spaces with appropriate answers: The focal length of a convex lens is 'f'. The object is at a distance x from the focus. If the image formed is real, then the magnification is _____.

Fill in the blank spaces with appropriate answers: Two lenses of powers +4D and -4D are joined together. The focal length of the combination is ____.