Physics [3 Mark Question Answer]

How will you decide whether a given piece of glass is a concave lens, convex lens, or a plane glass plate?

Do we expect any change in the position, nature, and size of the image
(i) formed by a concave lens,
(ii) with a change in the position of the object?

Point out the difference between a convex lens and a concave lens.

Define the term magnifying power of a simple microscope. How does it depend on the focal length of the lens used?

In sunglasses, both of its surfaces are curved, yet their behaviour is neither like a convex lens nor like a concave lens. State the reason.

Ranbir claims to have obtained an image twice the size of the object with a concave lens. Is he correct? Give a reason for your answer.

What is the difference between a double convex and a bi-convex lens?

Do we expect any change in the position, nature, and size of the image
(i) formed by a concave lens,
(ii) with a change in the position of the object?

A concave mirror and convex lens are held in water. What changes, if any, do you expect in their focal length?

Write the three characteristics of the image formed by a convex lens of focal length 20 cm for the object at distance (i) 10 cm, (ii) 30 cm, (iii) 40 cm, (iv) 60 cm from the lens.

A lens forms an upright and diminished image of an object, irrespective of its position. What kind of lens is this? Draw an outline ray diagram to show the formation of the image. State the position and one more characteristic of the image.

Draw a ray diagram to show the formation of an inverted and diminished image of an object by a lens. Name the lens used. State the position of the object with respect to the lens used. State one more characteristic of the image.

Show by a diagram, the refraction of two light rays incident parallel to the principal axis on a concave lens by treating it as a combination of a glass block and two triangular glass prisms.

What is optical centre of a thin lens? Draw diagram/diagrams to illustrate it.

What is a simple microscope or a magnifying glass? Draw a ray diagram to show its function.

Write down the characteristic of the image formed when the object is between F and the lens?

Write down the characteristic of the image formed when the object is between F and 2F?

Draw the ray diagrams of a converging lens, when the object is placed at 2F on the principal axis. Write down the nature, position, and size of the image in both cases. Use only two rays in the diagrams.

Draw the ray diagrams of a converging lens, when the object is placed at a distance greater than twice the focal length of the lens.

The following diagram shows the object O and the image I formed by a lens. Copy the diagram and on it mark the positions of the lens LL’ and focus (F). Name the lens.

The given ray diagram illustrates the experimental set up for the determination of the focal length of a converging lens using a plane mirror.

(i) State the magnification of the image formed.
(ii) Write two characteristics of the image formed.
(iii) What is the name given to the distance between the object and optical centre of the lens in the above diagram?

The diagram showed a lens as a combination of one glass block and two prisms. Complete the ray diagram and show the part of the incident ray AB after passing through the lens.
(i) Name of the lens formed by the combination.
(ii) What is the line XX’ called?
(iii) Mark the focus F.

Define the principal focus of a concave lens.

Define the principal focus of a convex lens.

(i) Draw a ray diagram to show how the lens can be used as a ‘magnifying glass’? State the nature of the lens.
(ii) In what respect does the image in (i) above different from the image formed by a concave lens?

What is a magnifying glass (or a simple microscope)? Draw a ray diagram to show how a convex lens may be used as a magnifying glass. Where should the object be placed? State three characteristics of the image formed.

Draw images in case of a concave lens when the object is at infinity.

Define the optical centre of a lens.

Define the principal axis.

The diagram on right shows a ray of white light AB incident on a rectangular glass block, which is silvered at the lower surface. This ray is partly reflected and partly refracted.

(i) Copy the diagram and trace the path of the refracted and reflected ray. Show at least two rays emerging from the surface ‘PQ’
(ii) How many images are formed in the above case? Which image is the brightest?

Draw a ray diagram to illustrate the formation of an enlarged and upright image of an object by a lens. Name the lens used. Where should the object be placed relative to the lens? Will the image be real or virtual? Name a device where this action of lens is used.

Name the types of lenses.