Optical Instruments Physics - Optical Instruments

Can virtual image be formed on the retina in a seeing process?

A simple microscope using a single lens often shows coloured image of a white source. Why?

A simple microscope using a single lens often shows coloured image of a white source. Why?

A simple microscope is rated 5 for a normal relaxed eye. What will be its magnifying power for a relaxed farsighted eye whose near point is 40cm?

A compound microscope forms an inverted image of an object. In which of the following cases it is kely to create difficulties?

1. Looking at small germs.
2. Looking at circular spots.
3. Looking at a vertical tube containing some water.

Why are the magnification properties of microscopes and telescopes defined in terms of the ratio of angles and not in terms of the ratio of sizes of objects and images?

A magnifying glass is a converging lens placed close to the eye. A farsighted person uses spectacles having converging lenses. Compare the functions of a converging lens used as a magnifying glass and as spectacles.

A nearsighted person cannot see beyond 25cm. Assuming that the separation of them glass from the eye is 1cm, find the power of lens needed to see distant objects.

A person is viewing an extended object. If a converging lens is placed in front of his eyes, will he feel that the size has increased?

Can the image formed by a simple microscope be projected on a screen without using any additional lens or mirror?

By mistake, an eye surgeon puts a concave lens in place of the lens in the eye after a cataract operation. Will the patient be able to see clearly any object placed at any distance?

A lady cannot see objects closer than 40cm from the left eye and closer than 100cm from the right eye. While on a mountaineering trip, she is lost from her team. She tries to make an astronomical telscope from her reading glasses to look for her teammates.

1. Which glass should she use as the eyepiece?
2. What magnification can she get with relaxed eye?

A child has near point at 10cm. What is the maximum angular magnification the child can have with a convex lens of focal length 10cm?

The maximum focal length of the eye-lens of a person is greater than its distance from the retina. The eye is:

1. Always strained in looking at an object.
2. Strained for objects at large distances only.
3. Strained for objects at short distances only.
4. Unstrained for all distances.

When we see an object, the image formed on the retina is:

1. Real.
2. Virtual.
3. Erect.
4. Inverted.

The size of an object as perceived by an eye depends primarily on:

1. Actual size of the object.
2. Distance of the object from the eye.
3. Aperture of the pupil.
4. Size of the image formed on the retina.

 A normal eye is not able to see objects closer than 25cm because:

1. The focal length of the eye is 25cm.
2. The distance of the retina from the eye-lens is 25cm.
3. The eye is not able to decrease the distance between the eye-lens and the retina beyond a limit.
4. The eye is not able to decrease the focal length beyond a limit.

In which of the following the final image is erect?

1. Simple microscope.
2. Compound microscope.
3. Astronomical telescope.
4. Galilean telescope.

Find the maximum magnifying power of a compound Microscope having a 25 diopter lens as the objective, a 5 diopter lens as the eyepiece and the separation 30cm between the two lenses. The least distance for clear vision is 25cm.

An object is placed at a distance of 30cm from a converging lens of focal length 15cm. A normal eye (near point 25cm, far point infinity) is placed close to the lens on the other side.

1.  Can the eye see the object clearly?
2.  What should be the minimum separation between the lens and the eye so that the eye can clearly see the object?
3.  Can a diverging lens, placed in contact with the converging lens, help in seeing the object clearly when the eye is close to the lens?

A compound microscope consists of an objective of focal length 1cm and an eyepiece of focal length 5cm. An object is placed at a distance of 0.5cm from the objective. What should be the separation between the lenses so that the microscope projects an inverted real image of the object on a screen 30cm behind the eyepiece?

A lady uses +1.5D glasses to have normal vision from 25cm onwards. She uses a 20D lens as a simple microscope to see an object. Find the maximum magnifying power if she uses then microscope

1. Together with her glass
2. Without the glass. Do the answers suggest that an object can be more clearly seen through a microscope without using the correcting glasses?

An optical instrument used for angular magnification has a 25D objective and a 20D eyepiece. The tube length is 25cm when the eye is least strained.

1. Whether it is a microscope or a telescope?
2. What is the angular magnification produced?