If the image formed by a lens for all positions of the object placed in front of it is always virtual, erect and diminished, state the type of the lens. Draw a ray diagram in support of your answer. If the numerical value of focal length of such a lens is 20cm, find its power in new cartesian sign conventions.

Between which two points of concave mirror should an object be placed to obtain a magnification of:

1. −3
2. +25
3. −0.4

Which type of lens is:

1. A converging lens, and which is.
2. A diverging lens? Explain your answer with diagrams.

The image formed by a spherical mirror is real, inverted and is of magnification - 2. If the image is at a distance of 30 cm from the mirror, where is the object placed ? Find the focal length of the mirror. List two characteristics of the image formed if the object is moved 10 cm towards the mirror.

A spherical mirror produces an image of magnification -1 on a screen placed at a distance of 50cm from the mirror.

1. Write the type of mirror.
2. find the distance of the image from the object.
3. What is the focal length of the mirror?
4. Draw the ray diagram to show the image formation in this case.

With the help of a diagram, explain why the image of an object viewed through a concave lens appears smaller and closer than the object.

A convex lens of focal length 25cm and a concave lens of focal length 10cm are placed in close contact with one another.

1. What is the power of this combination?
2. What is the focal length of this combination?
3. Is this combination converging or diverging?

The image of an object formed by a lens is of magnification - 1. If the distance between the object and its image is 60 cm, what is the focal length of the lens? If the object is moved 20 cm towards the lens, where would the image be formed? State reason and also draw a ray diagram in support of your answer.

A diverging mirror of radius of curvature 40cm forms an image which is half the height of the object. Find the object and image positions.

An image formed on a screen is three times the size of the object. The object and screen are 80cm apart when the image is sharply focussed.

1. State which type of lens is used.
2. Calculate focal length of the lens.