Back to Optical Instruments

Set 2 of 2 · Questions 31-40 of 40

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher

Mere Teacher · Previous Year Questions

JEE Main Physics · Optical Instruments · Set 2 (Q31-40)

QR code to mereteacher.com

Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.

  1. 31.
    A person with normal near point 25 cm using a compound microscope with objective of focal length 8.0 mm and an eye piece of focal length 2.5 cm can bring an object placed at 9.0 mm from the objective in sharp focus. The separation between two lenses and magnification respectively are:
    1. (1)9.47 cm, 88
    2. (2)3.36 cm, 44
    3. (3)6.00 cm, 22
    4. (4)7.49 cm, 11
  2. 32.
    If the focal length of objective lens is increased then magnifying power
    1. (1)microscope will increase but that of telescope decrease.
    2. (2)microscope and telescope both will Increase.
    3. (3)microscope and telescope both will decrease.
    4. (4)microscope will decrease but that of telescope will increase.
  3. 33.
    In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens. The eye-piece forms a real image of this line. The length of this image is I. The magnification of the telescope is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  4. 34.
    An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20. To the observer the tree appears:
    1. (1)10 times nearer
    2. (2)20 times taller
    3. (3)20 times nearer
    4. (4)10 times taller
  5. 35.
    Given below are two statements: One is labeled as Assertion and the other is labeled as Reason . Assertion For a simple microscope, the angular size of the object equals the angular size of the image. Reason :Magnification is achieved as the small object can be kept much closer to the eye than and hence itsubtends a large angle. In the light of the above statements, choose the most appropriate answer from theoptions given below:
    1. (1)Both and are true but is NOT the correct explanationof
    2. (2)Both and are true and is the correct explanation of
    3. (3) is true but is false
    4. (4) is false but is true
  6. 36.
    How should people wearing spectacles work with a microscope
    1. (1)They cannot use the microscope at all
    2. (2)They should keep on wearing their spectacles
    3. (3)They should take off spectacles
    4. (4)(b) and (c) is both way
  7. 37.
    A microscope was initially placed in air (refractive index 1). It is then immersed in oil (refractive index 2). For a light whose wavelength in air is , calculate the change of microscope's resolving power due to oil and choose the correct option
    1. (1)Resolving power will be in the oil than it was in the air
    2. (2)Resolving power will be twice in the oil than it was in the air.
    3. (3)Resolving power will be four times in the oil than it was in the air.
    4. (4)Resolving power will be in the oil than it was in the air.
  8. 38.
    A microscope is focused on an object at the bottom of a bucket. If liquid with refractive index is poured inside the bucket, then microscope have to be raised by 30 cm to focus the object again. The height of the liquid in the bucket is :
    1. (1)75 cm
    2. (2)50 cm
    3. (3)18 cm
    4. (4)12 cm
  9. 39.
    In an astronomical telescope in normal adjustment a straight black line of length is drawn on inside part of objective lens. The eye‐piece forms a real image of this line. The length of this image is . The magnification of the telescope is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  10. 40.
    A scientist is observing a bacteria through a compound microscope. For better analysis and to improve its resolving power he should. (Select the best option)
    1. (1)Increase the wave length of the light
    2. (2)Increase the refractive index of the medium between the object and objective lens
    3. (3)Decrease the focal length of the eye piece
    4. (4)Decrease the diameter of the objective lens