MCQs on Optical Microscope For NEET

Optical instruments are the devices which process light waves to enhance an image for a more clear view. The optical microscope is of two types: a simple microscope and a compound microscope. An optical microscope uses a single lens or a group of lenses for magnification.

Optical microscope

Q1: What is the ratio of resolving power of an optical microscope for wavelengths λ1= 4000 Å and λ2= 6000 Å?

  1. 2:3
  2. 3:2
  3. 6:25
  4. 16:9

Answer: (b) 3:2

Q2: Two identical glass (μg=3/2) equi – convex lenses of focal length f each are kept in contact. The space between the two lenses is filled with water ((μw=4/3). The focal length of the combination is

  1. f/3
  2. f
  3. 4f/3
  4. 3f/4

Answer: (d) 3f/4

Q3: The objective and the eye-piece of the compound microscope having a focal length of 0.95 cm and 5 cm, respectively, are kept at a distance of 20 cm. At a distance of 25 cm the large image is formed. Calculate the total magnification.

  1. 84
  2. 80
  3. 94
  4. 75

Answer: (c) 94

Q4: A vertical microscope is focused on a point at the bottom of an empty tank. Then water (μ=4/3) is poured into the tank up to a height of 4 cm. After which a liquid that does not mix with water is poured over it up to a height of 2 cm above the water. The refractive index of the liquid is 3/2. What should be the vertical distance through which the microscope must be moved to bring the object in focus again?

  1. 2.61 cm
  2. 1.67 cm
  3. 5 cm
  4. 4.1 cm

Answer: (b) 1.67 cm

Q5: Using a microscope a glass plate of 5 mm is viewed from the above. The microscope is lowered by 3 mm to view the bottom surface of the glass. What is the refractive index of the glass?

  1. 2
  2. 1.66
  3. 2.25
  4. 1.4

Answer: (b) 1.66

Q6: A microscope is used to focus on an object at the bottom of a beaker. The microscope is raised by 1 cm. To what height should the water be poured to bring the object in focus again. Refractive index of water is 4/3.

  1. 1 cm
  2. 4/3 cm
  3. 4 cm
  4. 3 cm

Answer: (c) 4 cm

Q7: Resolving power of a microscope depends upon

  1. The focal length and aperture of the eye lens
  2. The focal length and objective of the eye lens
  3. The apertures of the objective and the eye lens
  4. The wavelength of light illuminating the object

Answer: (d) The wavelength of light illuminating the object

Q8: The magnification power of a compound microscope does not depend upon

  1. The focal length and aperture of the eye lens
  2. The apertures of the objective lens
  3. Tube length of the microscope
  4. None of the above

Answer: (b) The apertures of the objective lens

Q9: Differentiation capacity of a compound microscope is

  1. 27.5 μm
  2. 2.75 μm
  3. 0.275 μm
  4. None

Answer: (c) 0.275 μm

Q10: Resolving power of light microscope is

  1. 2 mm
  2. 0.2 mm
  3. 0.1 mm
  4. 1 mm

Answer: (b) 0.2 mm

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