Question

a convex mirror on focal length 20 cm forms image of magnification 35 for one position of the
object. The object is shifted by 16 3 cm towards the mirror. By what distance and we
the image will move.​

Answer 1

Explanation:

Focal length of mirror is-40 cm (‘-’ sign because it is a concave mirror)

Magnification= m = −vu=4−vu=4

−v=4u−v=4u

v=−4uv=−4u

now , by lens makers formula

1u+1v=1f1u+1v=1f

uvu+v=fuvu+v=f

puttingv=−4u,v=−4u,

It becomes,

−4u2−3u=−40−4u2−3u=−40

−4u−3=−40−4u−3=−40

u=−30u=−30

putting u=−30u=−30in v=−4uv=−4u

we get v=120cm

I think help you..