Question

the refractive index of a lens is 1.5 and object is kept in front of the lens at a distance of 30 cm and image is fromed at a distance of 20 cm find the focal length of the lens what is nature of the lens​

Answer 1

Explanation:

Given ,

U = - 30 cm

V = + 20 cm

2 miu = 1.5

F = ?

1/F =1/V - 1/U

1/F =1/20 - ( - 1/30)

1/F =1/20 + 1/30

1/F = 3+2/60 =5/60 =12

So , F =12 cm

Nature of lens :-

• Lens must be convex. (+ve sign shows that lens is convex)