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Optical Instruments Physics - Optical Instruments

Jharkhand Board (JAC) - STD 12 Science - Physics (Jharkhand - English Medium). 58 questions in this chapter.

Question types

Optical Instruments question types

58 questions across 6 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.

58
Questions
6
Question groups
5
Question types
Sample Questions

Optical Instruments questions

One sample from each question group in this chapter. Select any group above to see the full set with answer keys.

Q 1M.C.Q (1 Marks)1 Mark
The maximum focal length of the eye-lens of a person is greater than its distance from the retina. The eye is:
  • ✓
    Always strained in looking at an object.
  • B
    Strained for objects at large distances only.
  • C
    Strained for objects at short distances only.
  • D
    Unstrained for all distances.

Answer: A.

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Q 2M.C.Q (1 Marks)1 Mark
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?
  • A
    25cm to 200cm.
  • ✓
    18cm to 200cm.
  • C
    25cm to 300cm.
  • D
    18cm to 300cm.

Answer: B.

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Q 3M.C.Q (1 Marks)1 Mark
A man is looking at a small object placed at his near point. Without altering the position of his eye or the object, he puts a simple microscope of magnifying power 5X before his eyes. The angular magnification achieved is:
  • A
    5
  • B
    2.5
  • ✓
    1
  • D
    0.2

Answer: C.

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Q 4M.C.Q (1 Marks)1 Mark
The size of an object as perceived by an eye depends primarily on:
  • A
    Actual size of the object.
  • B
    Distance of the object from the eye.
  • C
    Aperture of the pupil.
  • ✓
    Size of the image formed on the retina.

Answer: D.

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Q 5M.C.Q (1 Marks)1 Mark
To increase the angular magnification of a simple microscope, one should increase:
  • A
    The focal length of the lens.
  • ✓
    The power of the lens.
  • C
    The aperture of the lens.
  • D
    The object size.

Answer: B.

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Q 102 Marks Questions2 Marks
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?
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Q 122 Marks Questions2 Marks
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.
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Q 133 Marks Question3 Marks
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?
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Q 143 Marks Question3 Marks
The magnifying power of a simple microscope is given by $1+\frac{\text{D}}{\text{f}},$ where D is the least distance for clear vision. For farsighted persons, D is greater than the usual. Does it mean that the magnifying power of a simple microscope is greater for a farsighted person as compared to a normal person? Does it mean that a farsighted person can see an insect more clearly under a microscope than a normal person?
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Q 153 Marks Question3 Marks
A person looks at different trees in an open space with the following details. Arrange the trees in decreasing order of their apparent sizes.
Tree Height(m) Distance form the eye(m)
A 2.8 50
B 2.5 80
C 1.8 70
D 2.8 100
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Q 163 Marks Question3 Marks
The magnifying power of a converging lens used as a simple microscope is $\Big(1+\frac{\text{D}}{\text{f}}\Big).$ A compound microscope is a combination of two such converging lenses. Why don't we have magnifying power $\Big(1+\frac{\text{D}}{\text{f}_\text{o}}\Big) \Big(1+\frac{\text{D}}{\text{f}_\text{o}}\Big)?$ In other words, why can the objective not be treated as a simple microscope but the eyepiece can?
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Q 173 Marks Question3 Marks
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.
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Q 185 Marks Questions5 Marks
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?
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Q 205 Marks Questions5 Marks
A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of 0.5cm and the tube length is 6.5cm. Find the focal length of the eyepiece.
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Q 215 Marks Questions5 Marks
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?
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Q 225 Marks Questions5 Marks
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?
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Q 24Case study (4 Marks)4 Marks
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?
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Q 25Case study (4 Marks)4 Marks
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?
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