Question

a concave lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will​

Answer 1

You can use this formula , Lens maker's formula.

1/f = ( n - 1)( (1/R1) - (1/R2) )

f:- focal length of the lens.

n:- (refractive index of material)/(refractive index of surrounding)

R1:- radii of curvature of left lens surface

R2:- radii of curvature of right lens surface

As it is a double convex lens having R1 and R2 , radii of curvature.

#So we know ( (1/R1) - (1/R2) )

Can't be negative.

I will tell u, why I m finding negative or positive focal length.

So, next , it's all depends upon ‘n'

So if ‘n' > 1 then

‘n - 1′ will be positive, and if n < 1 then n - 1 will be negative.

So if focal length is negative then it will be diverging lens(Concave)

If focal length is positive then it will be converging lens(Convex).

Remember

’n' = refractive index of material / refractive index of surrounding.

For doing these type of problem.

Hope u understand.** mark it as brainly