# A Camera Fitted with a Lens of Focal Length 50 Mm is Being Used to Photograph a Flower that is 5 Cm in Diameter. the Flower is Placed 20 Cm in Front of the Camera Lens. at What Distance - Science

A camera fitted with a lens of focal length 50 mm is being used to photograph a flower that is 5 cm in diameter. The flower is placed 20 cm in front of the camera lens.

At what distance from the film should the lens be adjusted to obtain a sharp image of the flower?

#### Solution

Given:
Focal length, f = 50 mm = 5 cm
Object distance, u =-20 cm
Image distance, v = ?
Putting these values in lens formula, we get:

⇒1/v-1/u=1/f

⇒1/v-1/-20=1/5

⇒1/v+1/20=1/5

⇒1/v=1/5-1/20

⇒1/v=(20-5)/100

⇒1/v=15/100

⇒v=20/3

⇒v=6.66 cm

Film should be adjusted at a distance of 6.66 cm behind the lens.

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#### APPEARS IN

Lakhmir Singh Class 10 Physics (Science)
Chapter 5 Refraction of Light
Q 18.1 | Page 257