The size of the image of an object, which is at infinity, as formed by a convex lens of focal length 30 cm is 2 cm. If a concave lens of focal length 20 cm is placed between the convex lens and the image at a distance of 26 cm from the convex lens, calculate the new size of the image

Options

A. 1.25 cm
B. 2.5 cm
C. 1.05 cm
D. 2 cm

Answer

B

Explanation

For cancave lens, `u=+4cm,f=-20cm,v=?`
`(1)/(v)-(1)/(4)=(1)/(-20)`
`(1)/(v)=+(1)/(4)-(1)/(20)=(-4)/(20)impliesv=5cm`
`m=(v)/(u)implies(I)/(O)=(v)/(u)`
`(I)/(-2)=(5)/(4)`
`I=-2.5cm`