A bi-convex lens made of glass (refractive in | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(B) The focal length of a lens in a medium is given by the Lens Maker's Formula: $\frac{1}{f} = (\mu - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right)

Vedclass · Accepted Answer

Increase and change sign

Vedclass · Answer

(B) The focal length of a lens in a medium is given by the Lens Maker's Formula: $\frac{1}{f} = (\mu - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} ight)$.For a bi-convex lens in air $(f_a)$,$\frac{1}{f_a} = (_a\mu_g - 1) \left( \frac{2}{R} ight)$,where $_a\mu_g = 1.5$.When placed in a liquid $(f_l)$,the refractive index becomes $_l\mu_g = \frac{\mu_g}{\mu_l} = \frac{1.5}{1.7} \approx 0.88$.Thus,$\frac{1}{f_l} = (_l\mu_g - 1) \left( \frac{2}{R} ight) = (0.88 - 1) \left( \frac{2}{R} ight) = -0.12 \left( \frac{2}{R} ight)$.Comparing the two: $\frac{f_l}{f_a} = \frac{_a\mu_g - 1}{_l\mu_g - 1} = \frac{1.5 - 1}{\frac{1.5}{1.7} - 1} = \frac{0.5}{\frac{1.5 - 1.7}{1.7}} = \frac{0.5 	imes 1.7}{-0.2} = -4.25$.Since the ratio is negative,the focal length changes sign (from convex to concave behavior) and its magnitude increases by a factor of $4.25$.

$A$ bi-convex lens made of glass (refractive index $1.5$) is put in a liquid of refractive index $1.7$. Its focal length will

Similar Questions

The diameter of the Sun is $1.4 \times 10^9 \, m$ and its distance from the Earth is $10^{11} \, m$. What is the diameter of the image (in $cm$) formed by a convex lens of focal length $2 \, m$?

$A$ lens which has a focal length of $4 \; cm$ and a refractive index of $1.4$ is immersed in a liquid of refractive index $1.6$. What will be the new focal length in $cm$?

The distance between an object and its image produced by a converging lens is $0.72 \ m$. The magnification is $2$. What will be the magnification when the object is moved by $0.04 \ m$ towards the lens?

$A$ light ray hits the pole of a thin biconvex lens as shown in the figure. The angle made by the emergent ray with the optic axis will be

The ratio of the focal lengths of a convex lens when kept in air and when it is immersed in a liquid is $1: 2$. If the refractive index of the material of the lens is $1.5$,then the refractive index of the liquid is

Vedclass Test Series

Exam Paper Generator

Online Exam Module