Question

An object when placed in front of a convex lens forms a real image of 0.5 magnification. If the distance of the image from the lens is 24 cm, calculate focal length of the lens.​

Answer 1

Explanation:

It is given that image distance [v] = 24 cm.

The magnification [m] = 0.5

As per the rule of sign convention for lens, the measurement taken opposite to the direction of light is taken as negative.

As the image is real, so the image must be formed on the other side of the lens .

Hence, v = +24 cm

As the image is real, so the magnification is taken as negative.

Hence, m = -0.5

We are asked to calculate the focal length [f] of the lens.

The magnification in terms of v and f is given as -

m=f-v/f

mf=f-v

f=v/1-m

(24)/1-0.5

=16 cm

Hence, the focal length of the convex lens is 16 cm.

Answer 2

Concave mirror nature Convergent
Convex mirror nature Divergent
Type ‘s of Beam
Beam - group of rays
Convergent Beam
Parallel Beam
Divergent Beam
Source -
The objects which have their own heat and light are called Luminous
The objects which do not have their own heat and light are called Non Luminous
Formula - r divided by centre of curvature
So the answer will be 48 cm .