Define the following:
Focal length (f)

Define the following: Focal length of a mirror (f)

Define the following: Focus of a concave mirror (F)

Define the following: Focus of a convex mirror (F

Define the following: Principal Focus(F)

Answer the following questions: Define the following terms related to spherical mirrors: focal length

Answer the following questions : With reference to spherical lenses , state the meaning of the following terms or define the following terms and draw the diagrams to illustrate the same: focal length (f)

Answer the following questions : If two lenses of focal length f_1 and f_2 are kept in contact with each other , state the formula for the focal length of the combination . If p_1 and P_2 are the power of these lenses, state the formula for the power of the combination .

Fill in the blank: The focal length of a…….mirror is positive.

Fill in the blank: The focal length of a………mirror is negative..

Fill in the blanks : The focal length of a ………… lens is positive.