An image of a bright square is obtained on a screen with the aid of a convergent lens. The distance between the square and the lens is 40cm. The area of the image is nine times larger than that of the square. Select the correct statement(s):

Options

A. Image is formed at a distance of 120cm from the lens
B. Image is formed at a distance of 360cm from the lens
C. Focal length of the lens is 30cm
D. Focal length of the lens is 36cm

Answer

A, C

Explanation

`(v)/(u)=(3)/(1)rArrv=3u`
`(1)/(v)-(1)/(u)=(1)/(f),(1)/(3u)+(1)/(u)=(1)/(f)`
`f=30cm.`