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Exam NameLight QUESTIONS
DescriptionLight QUESTIONS and Answers exams contains the questions from various competitive exams.These questions are the part of previous year paper.These kind of questions would be helpful in preparing for exams like IAS, PCS, UPSC, NDA, CDS SSC, RRB, PSC, IBPS
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Question: In the human eye, the focussing is done by:

Answer:change in the convexity of the eye lens

Question: Two plane mirrors A and B are placed at a distance 12 cm apart facing towards each other. An object is placed in between them at a distance 8 cm from the mirror A. What will be the distance between the first two images formed in the mirror B ?

Answer:16 cm

Question: The focal length of the lens in a photographic camera is 5 cm. What is the power of the lens ?

Answer:+ 20 D

Question: The image formed on the retina of a human eye is

Answer:real ad inverted

Question: A lens, immersed in a liquid becomes in visible when -

Answer:the refractive index of the lens is equal to the refractive index of the liquid

Question: An equiconvex lens is prepared from a glass of refractive index 1.5. The radius of curvature of the surface is 0.5 m. The focal length of the lens is-

Answer:0.5 m

Question: A light wave travelling in a transparent homogeneous medium enters another homogeneous transparent medium of higher refractive index. The speed of light in the second medium;

Answer:is less than that in the first medium

Question: In a healthy human eye, the focussing is done by the

Answer:change in the convexity of the lens through ciliary muscles

Question: The magnifying power of a telescope can be increased by=

Answer:reducing the focal length of the eye piece

Question: An object is kept 5 cm in front of a concave mirror of focal length 15 cm. What will be the nature of the image ?

Answer:virtual, magnified

Question: Different objects at different distances are seen by the eye. The parameter that remains. Constant is-

Answer:the image distance from the eye lens

Question: How for must a girl stand in front of a concave spherical mirror of radius 120 cm to see an erect image of her face four times its natural size ?

Answer:45 cm from the mirror

Question: A far-sighted person has a near point at 100 cm. What must be the power of the correcting lens ?

Answer:+3.0 D

Question: Which one of the following is used to remove astigmatism for a human eye ?

Answer:cylindrical lens

Question: What is the essential difference between a terrestrial telescope and an astronomical telescope ?

Answer:a terrestrial telescope forms an erect image while an astronomical telescope forms an inverted image

Question: Optical fibre works on the principle of-

Answer:total internal reflection

Question: An air bubble in water will act like a -

Answer:concave lens

Question: Total internal reflection can take place when light travels from:

Answer:diamond to glass

Question: When a CD (compact disc used in audio ad video systems ) is seen in sunlight. Rainbow like colours are seen. This can be explained on the basis of the phenomenon of :

Answer:refraction diffraction and transmission

Question: diffusion of light in the atmosphere takes place due to:

Answer:dust particles