A transparent material bounded by two surfaces of which at least one is curved is called a .

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 _____.

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 _____.

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.

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?

The word KVPY is written on $\mathrm{a}$ board and viewed through different lenses such that board is at a distance beyond the focal length of the lens.

Ignoring magnification effects, consider the following statements.
$\left(\mathrm{I}\right)$ First image has been viewed from the planar side of a plano-concave lens and second image from the planar side of a plano-convex lens.
$\left(\mathrm{II}\right)$ First image has been viewed from the concave side of a plano-concave lens and second image from the convex side of a plano-convex lens.
$\left(\mathrm{III}\right)$ First image has been viewed from the concave side of a plano-concave lens and second image from the planar side of a plano-convex lens.
$\left(\mathrm{IV}\right)$ First image has been viewed from the planar side of a plano-concave lens and second image from the convex side of a plano-convexlens.

Which of the above statements are correct?

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.