Priyanka B Solutions for Chapter: Light : Reflection and Refraction, Exercise 5: Practice Problems-III

An object is $50 \mathrm{cm}$ 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 convex lens forms a real image $4$ times magnified at a distance of $60 \mathrm{cm}$ from the lens. Calculate the power of the lens.

A needle placed $45 \mathrm{cm}$ from a lens forms an image on a screen placed $90 \mathrm{cm}$ on the other side of the lens. Identify the type of lens. Determine its focal length and the power. What is the size of the image if the needle is $5 \mathrm{cm}$ in height?

A concave lens of focal length $20 \mathrm{cm}$ forms an image at a distance of $10 \mathrm{cm}$ from the lens. What is the distance of the object from the lens? Draw a ray diagram.

A divergent lens has focal length of $20 \mathrm{cm}$. At what distance should an object from the lens be placed so that an image is formed $10 \mathrm{cm}$ away from the lens? What is the magnification produced by the lens?

The image of an object formed by a convex lens is of the same size as that of the object. If the image is formed at a distance of $50 \mathrm{cm}$ from the lens, at what distance from the lens is the object placed? Find the focal length and power of the lens used.

What is the power of a convex lens of focal length $40 \mathrm{cm}$?

Two thin converging lenses of focal lengths $0.15 \mathrm{m}$ and $0.30 \mathrm{m}$ are held in contact with each other. Calculate the power and focal lengths of the combination.