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A projector lens has a focal length of 1...

A projector lens has a focal length of 10 cm. It produces a real image of a `2cm xx 2 cm` slide on a screen 5 metre from the lens. What is the size of the picture on the screen ?

A

`49 cm xx 49 cm `

B

`24 cm xx 24 cm `

C

`98 cm xx 98 cm `

D

`75 cm xx 75 cm `

Text Solution

Verified by Experts

The correct Answer is:
C
Projector lens is a convex lens.
`f=10 cm, v=500 cm`
`because (1)/(v)-(1)/(u)=(1)/(f)`
`therefore (1)/(u)=(1)/(v)-(1)/(f)=(1)/(500)-(1)/(10)= - (49)/(500)`
`therefore u= -(500)/(49) cm`
`therefore M=(I)/(o)-(v)/(u)=(500)/((500)/(49))=49`
`therefore ` The image is magnified 49 times.
`therefore ` Size of the picture is `(49xx2)cm xx (49xx2)cm`
`=98 cm xx 98 cm `
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