A diverging lens with a focal length magnitud | vedclass

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(B) For the diverging lens,the incident light is parallel,so the image is formed at its focus. Since it is a diverging lens,$f_1 = -25\ cm$.Using the

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real and at a distance of $40\ cm$ from the converging lens

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(B) For the diverging lens,the incident light is parallel,so the image is formed at its focus. Since it is a diverging lens,$f_1 = -25\ cm$.Using the lens formula $\frac{1}{v_1} - \frac{1}{u_1} = \frac{1}{f_1}$,with $u_1 = \infty$,we get $v_1 = f_1 = -25\ cm$.This image acts as a virtual object for the converging lens. The distance between the lenses is $d = 15\ cm$.The object distance for the converging lens is $u_2 = -(25 + 15) = -40\ cm$.For the converging lens,$f_2 = +20\ cm$. Using the lens formula $\frac{1}{v_2} - \frac{1}{u_2} = \frac{1}{f_2}$:$\frac{1}{v_2} - \frac{1}{-40} = \frac{1}{20}$$\frac{1}{v_2} = \frac{1}{20} - \frac{1}{40} = \frac{2-1}{40} = \frac{1}{40}$$v_2 = +40\ cm$.Since $v_2$ is positive,the final image is real and formed at a distance of $40\ cm$ from the converging lens.

$A$ diverging lens with a focal length magnitude of $25\ cm$ is placed at a distance of $15\ cm$ from a converging lens with a focal length magnitude of $20\ cm$. $A$ beam of parallel light falls on the diverging lens. The final image formed is:

Similar Questions

Two lenses are placed in contact with each other and the focal length of the combination is $80 \ cm$. If the focal length of one lens is $20 \ cm$,then the power of the other lens will be: (in $D$)

$A$ convex lens of focal length $30 \ cm$ forms an image of height $2 \ cm$ for an object situated at infinity. If a concave lens of focal length $20 \ cm$ is placed coaxially at a distance of $26 \ cm$ in front of the convex lens,what will be the size of the final image in $cm$?

The size of the image of an object at infinity, formed by a convex lens of focal length $30 \,cm$, is $2 \,cm$. If a concave lens of focal length $20 \,cm$ is placed between the convex lens and the image at a distance of $26 \,cm$ from the convex lens, what is the new size of the image (in $\,cm$)?

The focal length of a combination of lenses formed with lenses having powers of $+2.50 \ D$ and $-3.75 \ D$ will be .... $cm$.

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