Ray Optics (NEET Physics): Questions 81  85 of 105
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Question number: 81
» Ray Optics » Power of a Lens
Question
A slide projector lens has a focal length 10 cm. It throws an image of a 2cm × 2cm slide on a screen 5 m from the lens. Find the size of the picture on the screen
Choices
Choice (4)  Response  

a.  (78 × 78) cm ^{2} 

b.  (64 × 64) cm ^{2} 

c.  (88 × 88) cm ^{2} 

d.  (98 × 98) cm ^{2} 

Question number: 82
» Ray Optics » Lens Maker's Formula and Lens Formula
Question
An image is formed on the screen by a convex lens. When upper half part of lens is covered with black paper, then:
Choices
Choice (4)  Response  

a.  Half image is formed 

b.  Intensity of image will be enhanced 

c.  Full image is formed 

d.  None of the above 

Question number: 83
» Ray Optics » Power of a Lens
Question
If the focal length of a magnifier is 5 cm calculate the power of the lens.
Choices
Choice (4)  Response  

a.  15 D 

b.  20 D 

c.  10 D 

d.  5 D 

Question number: 84
» Ray Optics » Magnification
Question
A 0.5 cm high object is placed at 30 cm from a convex mirror whose focal length is 20 cm. Find the position and size of the image.
Choices
Choice (4)  Response  

a.  6 cm, 0.5 cm 

b.  12 cm, 0.2 cm 

c.  5 cm, 0.1 cm 

d.  18 cm, 0.2 cm 

Question number: 85
» Ray Optics » Resolving Power of Microscopes and Astronomical Telescopes
Question
An astronomical telescope has an angular magnification of magnitude 5 for distant objects. The separation between the objective and eyepiece is 36 cm and the final image is formed at infinity.
(1) The focal length of objective is 30 cm
(2) The focal length of objective is 25 cm
(3) The focal length of eye piece is 6 cm
(4) The focal length of eye piece is 12 cm
Select the correct answers and mark it according to the following codes:
Codes:
Choices
Choice (4)  Response  

a.  1, 2 and 3 are correct 

b.  1 and 3 are correct 

c.  1 and 2 are correct 

d.  2 and 4 are correct 
