Narendra Kumar Solutions for Chapter: Light - Reflection and Refraction, Exercise 4: PROBLEMS FOR PRACTICE

An object is placed at a distance of $50 \mathrm{cm}$ from a concave lens of focal length $25 \mathrm{cm}$. Find the position and nature of the image.

A convex lens has focal length of $18 \mathrm{cm}$. At what distance from the lens an object be placed so that it forms a real image three times the size of the object?

An object $50 \mathrm{cm}$ tall is placed on the principal axis of a convex lens. Its $20 \mathrm{cm}$ tall image is formed on the screen placed at a distance of $10 \mathrm{cm}$ from the lens. Calculate the focal length of the lens.

A concave lens has focal length of $10 \mathrm{cm}$. At what distance from the lens a $5 \mathrm{cm}$ tall object be placed so that it forms an image at $6 \mathrm{cm}$ from the lens? Also calculate the size of the image formed.

A convex lens has a focal length of $40 \mathrm{cm}$. Calculate its power.

A thin lens has a focal length of $-25 \mathrm{cm}$. What is the power of the lens? Is it convex or concave?

A convergent lens of power $8 \mathrm{D}$ is combined with a divergent lens of power $-10 \mathrm{D}$. Calculate focal length of the combination.

Convex lens of focal length $20 \mathrm{cm}$ and concave lens of focal length $10 \mathrm{cm}$ are placed in contact. Calculate (i) Total power of combination, (ii) What is the nature of the combination.