Question

an object 20 cm high is placed at a distance of 30 cm from a convex lens of focal length 20cm find the position nature and size of image​

Answer 1

u(object distance) = -20cm ( negative sign due to presence of object opposite to the direction of rays)

f(focal length) =+25cm (convex mirror has always positive focal length)

By mirror formula

1/f=1/v+1/u

1/25=-1/20+1/v

1/25+1/20=1/v

(4+5)/100=1/v

9/100=1/v

V=100/9

V=11.111cm ( image position)

Position of the image is behind the mirror since v comes out to be positive and the image is small in nature.