Optical Instruments Physics - Optical Instruments

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.

In which of the following the final image is erect?

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

A person A can clearly see objects between 25cm and 200cm. Which of the following may represent the range of clear vision for a person B having muscles stronger than A, but all other parameters of eye identical to that of A?

1. 25cm to 200cm.
2. 18cm to 200cm.
3. 25cm to 300cm.
4. 18cm to 300cm.

When objects at different distances are seen by the eye, which of the following remain constant?

1. The focal length of the eye-lens.
2. The object-distance from the eye-lens.
3. The radii of curvature of the eye-lens.
4. The image-distance from the eye-lens.

To increase the angular magnification of a simple microscope, one should increase:

1. The focal length of the lens.
2. The power of the lens.
3. The aperture of the lens.
4. The object size.

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?

The angular magnification of a system is less than one. Does it mean that the image formed is inverted?

A Galilean telescope is 27cm long when focused to form an image at infinity. If the objective has a focal length of 30cm, what is the focal length of the eyepiece?

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.

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.

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

A person has near point at 100cm. What power of lens is needed to read at 20cm if he/ she uses.

1. Contact lens,
2. Spectacles having glasses 2.0cm separated from the eyes?

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 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.

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?

An object is to be seen through a simple microscope of focal length 12cm. Where should the object be placed so as to produce maximum angular magnification? The least distance for clear vision is 25cm.

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

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?

The separation between the objective and the eyepiece of a compound microscope can be adjusted between 9.8cm to 11.8cm. If the focal lengths of the objective and the eyepiece are 1.0cm and 6cm respectively, find the range of the magnifying power if the image is always needed at 24cm from the eye.

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 professor reads a greeting card received on his 50th birthday with +2.5D glasses keeping the card 25cm away. Ten years later, he reads his farewell letter with the same glasses but he has to keep the letter 50cm away. What power of lens should he now use?

An eye can distinguish between two points of an object if they are separated by more than 0.22mm when the object is placed at 25cm from the eye. The object is now seen by a compound microscope having a 20D objective and 10D eyepiece separated by a distance of 20cm. The final image is formed at 25cm from the eye. What is the minimum separation between two points of the object which can now be distinguished?