Ray OpticsLens Maker's Formula and Lens Formula (NEET Physics): Questions 12  17 of 19
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Question number: 12
» Ray Optics » Lens Maker's Formula and Lens Formula
Question
A convex lens of focal length 20 cm is placed in contact with a diverging lens of unknown focal length. The lens combination acts as a converging lens and has a focal length of 30 cm. What is the focal length of the diverging lens
Choices
Choice (4)  Response  

a.   30 cm  
b.   60 cm  
c.   10 cm  
d.   90 cm 
Question number: 13
» Ray Optics » Lens Maker's Formula and Lens Formula
Question
In case of thin lens of focal length an object is placed at a distance from first focus and its image is formed at a distance from the second focus, find
Choices
Choice (4)  Response  

a. 
 
b. 
 
c. 
 
d. 

Question number: 14
» Ray Optics » Lens Maker's Formula and Lens Formula
Question
For a Planoconvex lens of radius of curvature 10 cm, the focal length is 30 cm, if the refractive index of the material of the lens is,
Choices
Choice (4)  Response  

a.  1.5  
b.  1.33  
c.  1.66  
d.  2.0 
Question number: 15
» Ray Optics » Lens Maker's Formula and Lens Formula
Question
Two thin lenses of focal length 60 & 20 cm in contact have a resultant focal length of,
Choices
Choice (4)  Response  

a.  15 cm  
b.  +30 cm  
c.  +15 cm  
d.  30 cm 
Question number: 16
» 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: 17
» Ray Optics » Lens Maker's Formula and Lens Formula
Question
A pin is placed 10 cm in front of a convex lens of focal length 20 cm, made of material having refractive index 1.5. The surface of the lens farther away from the pin is silvered and has a radius of curvature 22 cm. determine the position of the final image.
Choices
Choice (4)  Response  

a.  31 cm in front  
b.  11 cm in front  
c.  15 cm in front  
d.  21 cm in front 