Magnification of a lens can be defined as the ratio of object distance to image distance.

A student wants to obtain magnified image of an object AB as on a screen. Which one of the following arrangements shows the correct position of AB for him/her to be successful?

A converging lens forms a three times magnified image of an object, which can be taken on a screen. If the focal length of the lens is $30 \mathrm{cm}$, then the distance of the object from the lens is _____.

If a lens can converge the sun rays at a point $20 \mathrm{cm}$ away from its optical centre, the power of this lens is _____.

If the object is placed at a principal focus $\mathrm{F}_{1}$ of a convex lens, draw the ray diagram for the image formation.

An object is placed at a distance $24 \mathrm{cm}$ in front of a convex lens of focal length $8 \mathrm{cm}$.
(i) Calculate the distance of the image from the lens.
(ii) Calculate the magnification of the image.

Observe the following figure and complete the table.

Define Power of lens. Give its unit.

The following diagram shows the use of an optical device to perform an experiment of light.

As per the arrangement shown, the optical device is likely to be a _____.

The diagram shows an object '$O$', and its image '$I$' formed by a lens. In the diagram, draw the lens and the rays to show how the image is formed. Mark focus $F$, of the lens. Name the lens.

Draw a ray diagram to show the formation of an image when an object is placed between focus $\left({\mathrm{F}}_1\right)$ and optical centre $\left(\mathrm{O}\right)$ of a convex lens.

A point source $O$ is placed at a distance of $12.5 \mathrm{cm}$ from a converging lens of focal length $10 \mathrm{cm}$, on its principal axis as shown in the figure. Find the distance at which a diverging mirror of focal length $20 \mathrm{cm}$ should be placed, so that a real image is formed on the source itself.

A virtual, diminished image is formed when an object is placed between the optical centre and the principal focus of a lens.
(i) Name the type of lens which forms the above image.
(ii) Draw a ray diagram to show the formation of the image with the above stated characteristics.