Question

Rishi went to a palmist to show his palm. The palmist used a special len
for this purpose.
(i) State the nature of the lens and reason for its use.
(ii) Where should the palmist place/hold the lens so as to have a real and
magnified image of an object ?
(iii) If the focal length of this lens is 10 cm and the lens is held at a
distance of 5 cm from the palm, use lens formula to find the position
and size of the image.​

Answer 1

Answer:

i)convex lense. to magnify his palm.

ii)between f and 2f.

iii)f=+10

u=-5

{now use mirror formulae to calculate v}

Answer 2

i) The nature of lens is converging as it converge the beam of light passing through it at  a point.

ii) Palmist should hold the lens in such a way that the object is placed between f and 2f of lens so to have a magnified and real image.

iii) If f = -10 cm

u = -5 cm

then according to lens formula=   1/v-1/u=1/f

v= 10 cm

The image is magnified and is formed at  infinity.

Explanation:

Convex lens

It has narrow ends and broader center.