If the focal length of a magnifier is 5cm calculate (a) the power of the lens (b) the magnifying power of the lens for relaxed and strained eye.

If the focal length of a magnifier is 5cm calculate (a) the power of t

1.	If the focal length of a magnifier is 5cm calculate (a) the power of the lens (b) the magnifying power of the lens for relaxed and strained eye.
Answer» Solution :(a) As POWER of a LENS is RECIPROCAL of FOCAL length in m. `P=1/(( 5 TIMES 10^-2 m))=1/0.0` diopter =20D (b) For relaxed eye, MP is minimum and will be `MP=D/f=25/5=5` While for strained eye, MP is maximum and will be `MP=1+D/f=1+5=6`