Refraction Through Lens

Which of the following can form diminished, virtual and erect image of your face

Two plano convex lenses each of focal length $10 \mathrm{cm}$ and refractive index $\frac{3}{2}$ are placed as shown. In the space left, water (R.I$=\frac{4}{3}$) is filled. The whole arrangement is in the air. The optical power of the system is (in diopters)

The height of the image formed by a converging lens on a screen is 8 cm. For the same position of the object and screen again of size 12.5 cm is formed on the screen by shifting the lens. The height of the object

If an object is placed at the focus of a convex lens, its image is

How do you say that the focal length of a concave lens is always negative?

An object is placed at a distance $20 \mathrm{cm}$ from a convex lens of focal length $10 \mathrm{cm}$. Select the correct image distance and nature of the image.

The convex lens always gives small virtual image.

An object is put at a distance $25 \mathrm{cm}$ from the optical centre of a convex lens. If its real image is formed at a distance $30 \mathrm{cm}$ from the lens then its focal length is about -

A ray of light is incident on a lens parallel to its principal axis. After refraction, the ray passes through or appear to come from:

a converging lens

Which one of the following materials cannot be used to make a lens?

The distance between an object and the screen is 100 cm. A lens produces an image on the screen when placed at either of the position 40 cm apart. The power of the lens is

A diverging lens of focal length 20 cm and converging mirror of focal length 10 cm are placed coaxially at a separation of S cm. Where an object should be placed so that a real image is formed at the object itself?

A double concave lens made of a material of refractive index 1.5 having a focal length of 10 cm is immersed in liquid of refractive index 3.0. The lens will behave as

A convex lens produces a real image m times the size of the object. What will be the distance of the object from the lens?

Given below are a few steps (not in proper sequence) followed in the determination of focal length of a given convex lens by obtaining a sharp image of a distant object—

$\left(A\right)$ Measure the distance between the lens and screen.

$\left(B\right)$ Adjust the position of the lens to form a sharp image.

$\left(C\right)$ Select a suitable distant object.

$\left(D\right)$ Hold the lens between the object and the screen with its faces parallel to the screen.

The correct sequence of steps for determination of focal length is—

If a ray of light passes along the principal axis of a convex lens, it

What is the shape of a 1/v versus 1 /u graph?

What do you mean by focal plane of a lens ?
 

Concave lens is also known as