Question

A concave Lens of focal length 15 cm forms an image of 10 cm from the Lens. how far is the object placed from the Lens ? draw the ray diagram.

Answer 1

we know that,

1/f= 1/v- 1/u
where v is image distance and u is object distance

so we know that ,
f=15cm
v=10cm

object distance is ,
1/u= 1/15+ 1/10
1/u=1/6

therefore the object must be placed at a distance of 6 cm.

Answer 2

Hey You ❤

Your Answer :--

Given :

Focal length of concave lens, f = - 15 cm

Image distance, v= - 10 cm

Lens Formula :

According to the lens formula,

1/v - 1/u = 1/f

1/u = 1/v - 1/f

1/u = -1/10 - ( -1/15)

1/u = -1/10 + 1/15 = -5/150

u = - 30 cm

The negative value of u indicates that the object is placed 30 cm in front of the lens.

Note : For Ray Diagram please see attached file :)

Glad To Help :D

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