The given lens is broken into four parts and | vedclass

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

Question

(B) When a lens is cut into two equal parts along the principal axis (transverse direction),the focal length of each part becomes $2f$.In this problem

Vedclass · Accepted Answer

$f/2$

Vedclass · Answer

(B) When a lens is cut into two equal parts along the principal axis (transverse direction),the focal length of each part becomes $2f$.In this problem,the lens is cut into four parts. Each part acts as a lens with a focal length of $2f$.When these four parts are placed in contact,the equivalent focal length $f_{	ext{eff}}$ is given by the formula for lenses in contact:$\frac{1}{f_{	ext{eff}}} = \frac{1}{f_1} + \frac{1}{f_2} + \frac{1}{f_3} + \frac{1}{f_4}$Substituting the values $f_1 = f_2 = f_3 = f_4 = 2f$:$\frac{1}{f_{	ext{eff}}} = \frac{1}{2f} + \frac{1}{2f} + \frac{1}{2f} + \frac{1}{2f}$$\frac{1}{f_{	ext{eff}}} = \frac{4}{2f} = \frac{2}{f}$Therefore,$f_{	ext{eff}} = \frac{f}{2}$.

The given lens is broken into four parts and rearranged as shown. If the initial focal length is $f$,then after rearrangement,the equivalent focal length is

Similar Questions

An achromatic combination of lenses is formed by joining

The focal length of a lens of dispersive power $0.45$ which should be placed in contact with a convex lens of focal length $84 \,cm$ and dispersive power $0.21$ to make the achromatic combination from the two lenses,in $cm$ is

$A$ beam of parallel rays is brought to a focus by a plano-convex lens. $A$ thin concave lens of the same focal length is joined to the first lens. The effect of this is:

Assertion: Two convex lenses joined together cannot produce an achromatic combination.
Reason: The condition for achromatism is $\frac{\omega_1}{f_1} + \frac{\omega_2}{f_2} = 0$,where symbols have their usual meaning.

$A$ convex lens of focal length $40 \ cm$ is in contact with a concave lens of focal length $25 \ cm$. The power of the combination is:

Vedclass Test Series

Exam Paper Generator

Online Exam Module