NEET Physics Optical Instruments Set A

a) real and enlarged

b) virtual and diminished

c) real and diminished

d) virtual and enlarged

Answer: real and enlarged

Question: An astronomical telescope has a large aperture to

a) have high resolution

b) increases span of observation

c) have low dispersion

d) reduce spherical aberration

Answer: have high resolution

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

a) the power of the lens

b) the aperture of the lens

c) the object size

d) the focal length of the lens

Answer: the power of the lens

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

a) the eye is not able to decrease the focal length beyond a limit

b) the eye is not able to decrease the distance between the eye-lens and the retina beyond a limit

c) the distance of the retina from the eye-lens is 25 cm

d) the focal length of the eye is 25 cm

Answer: the eye is not able to decrease the focal length beyond a limit

Question: Resolving power of a telescope increases with

a) increase in apeture of objective

b) increase in aperture of eye piece

c) increase in focal length of objective

d) increase in focal length of eye-piece

Answer:  increase in apeture of objective

Question:  A normal eye has retina 2cm behind the eye lens. What is the power of the eye-lens when the eye is fully relaxed ?

a) 50 D

b) 54 D

c) 40 D

d) 45 D

Answer: 50 D

Question:  The focal length of the objective of a telescope is 60 cm. To obtain a magnification of 20, the focal length of the eye piece should be

a) 3 cm

b) 4 cm

c) 5 cm

d) 2 cm

Answer: 3 cm

Question: If the focal length of objective lens is increased then magnifying power of

a) microscope will decrease but that of telescope increase.

b) microscope and telescope both will decrease

c) microscope and telescope both will increase

d) microscope will increase but that of telescope decrease

Answer:  microscope will decrease but that of telescope increase.

Question:

a) 1.5 rad

b) 0.2 rad

c) 3.2 rad

d) 6.1 rad

Answer: 1.5 rad

Question:  The magnifying power of a telescope is 9. When it is adjusted for parallel rays, the distance between the objective and the eye piece is found to be 20 cm. The focal length of lenses are

a) 18 cm, 2 cm

b) 11 cm, 9 cm

c) 10 cm, 10 cm

d) 15 cm, 5 cm

Answer:  18 cm, 2 cm