The focal length of a convex lens is
The focal length of a convex lens:
Therefore, the focal length of a convex lens is positive.
Complete the following sentences :
(a) If half of a convex lens is covered, the focal length ..................... change, but the intersity of image ......................
(b) A convex lens is placed in water. Its focal length will ..................
(c) The focal length of a thin convex lens is ............... than that of a thick convex lens.
The lens of power + 1.0 D is :
(a) convex of focal length 1.0 cm
(b) convex of focal length 1.0 m
(c) concave of focal length 1.0 cm
(d) concave of focal length 1.0 m
Which of the following lenses would you prefer to use while reading small letters found in a dictionary?
(a) A convex lens of focal length 50 cm
(b) A concave lens of focal length 50 cm
(c) A convex lens of focal length 5 cm
(d) A concave lens of focal length 5 cm