Physics [LIGHT AND HUMAN EYE] Questions for Railway ALP Stage-II Exam : 6th December 2018

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1. A periscope works on the principle of
एक पेरिस्कोप किस सिद्धांत पर काम करता है?
(a) refraction / अपवर्तन
(b) total internal reflection / कुल आंतरिक प्रतिबिंब
(c) diffraction / विवर्तन
(d) reflection / प्रतिबिंब

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S1. Ans.(d)
Sol. A periscope works on the Laws of Reflection which states that the light from the object falls on one mirror at a 45o angle from the object and is reflected.

2. Which one of the following lenses should be used to correct the defect of astigmatism
दृष्टिवैषम्य के दोष को ठीक करने के लिए निम्नलिखित में से कौन से लेंस का उपयोग किया जाना चाहिए?
(a) Cylindrical lens/ बेलनाकार लेंस
(b) Concave has/ अवतल लेंस
(c) convex lens/ उत्तल लेंस
(d) Bifocal lens/ बाइफोकल लेंस

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S2. Ans.(a)
Sol. Astigmatism requires an additional “cylinder” lens power to correct the difference between the powers of the two principal meridians of the eye.

3. In a laser (say neon laser) all the atoms emit the light waves of
एक लेजर में (नियॉन लेजर) सभी परमाणु प्रकाश तरंगों को उत्सर्जित करते हैं-
(a)Same frequency / समान आवृति
(b)Same amplitude / समान आयाम
(c)Same phase / समान चरण
(d)All the above / यह सभी

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S3. Ans.(d)
Sol. In a laser (say neon laser) all the atoms emit the light waves of same frequency ,same amplitude and same phase.

4. ‘Short-sight’ in human eye can be corrected by using proper
मानव आंखों में ‘निकट दृष्टि’ किस का उपयोग करके सही किया जा सकता है?
(a) convex lens/ उत्तल लेंस
(b)concave lens / अवतल लेंस
(c) cylindrical lens/ बेलनाकार लेंस
(d) bifocal lens/ बाइफोकल लेंस

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S4. Ans.(b)
Sol. Short-sight’ in human eye can be corrected by using proper concave lens.

5. Fiber optics work on the principle of
फाइबर ऑप्टिक्स किस सिद्धांत पर कार्य करता हैं?
(a) scattering of light/ प्रकाश प्रकीर्णन
(b) total internal absorption/ कुल आंतरिक अवशोषण
(c) total internal reflection/ कुल आंतरिक प्रतिबिंब

(d) optical rotation / ऑप्टिकल रोटेशन
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S5. Ans.(c)
Sol. The optical fibre is a device which works on the principle of total internal reflection by which light signals can be transmitted from one place to another with a negligible loss of energy.

6. Energy of ultraviolet rays is greater than
पराबैंगनी किरणों की ऊर्जा किस से अधिक है?
(a) infrared rays/ अवरक्त किरणों
(b) gamma rays/ गामा किरणें
(c) X-rays/ एक्स-रे
(d) cosmic rays/ ब्रह्मांडीय किरणों

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S6. Ans.(a)
Sol. Electromagnetic spectrum is classified into according to the frequency of the wave: these types include, in order of increasing frequency, radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

7. Stars appear twinkling because of …….of light.
सितारे प्रकाश के ________ कारण चमकते हुए दिखाई देते हैं?
(a) reflection / प्रतिबिंब
(b) scattering / प्रकाश प्रकीर्णन
(c) emission / उत्सर्जन
(d) asbsorption / अवशोषण

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S7. Ans.(b)
Sol. When light passing through our environment , the dust, air and other particles cause scattering of light. Due to which the position of star appears quite different and sometime light entering our eyes, due to scattering , become brighter and deemer .

8. In mirrors, the back surface is coated with a thin layer of
दर्पण में, पिछली सतह _______ की पतली परत के साथ लेपित होती है ?
(a) mercury / पारा
(b) silver / चांदी
(c) red oxide/ लाल ऑक्साइड
(d) silver nitrate / सिल्वर नाइट्रेट

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S8. Ans.(d)
Sol. In mirrors, the back surface is coated with a thin layer of silver nitrate .

9. An optically regular plane surface reflects a beam of light
एक आप्टिक्ली नियमित समतल सतह प्रकाश की बीम को प्रतिबिंबित करता है
(a) as a parallel beam in one direction / एक दिशा में समानांतर बीम के रूप में
(b) as diffused beams in all direction /सभी दिशाओं में विसरित बीम के रूप में
(c) as parallel beams in all direction / सभी दिशाओं में समानांतर बीम के रूप में
(d) as a different beam in one direction / एक दिशा में एक अलग बीम के रूप में

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S9. Ans.(a)
Sol. a parallel beam of incident light is reflected as a parallel beam in one direction. In this case , parallel incident rays remain parallel even after reflection and go only in one direction and it occurs from smooth surfaces like that of a plane mirror or highly polished metal surfaces.

10. Who measured the velocity of light first?
पहली बार प्रकाश का वेग किसने मापा था?
(a) Galileo/ गैलीलियो
(b) Newton/ न्यूटन
(c) Roemer / रोमर
(d) Einstein / आइंस्टीन

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S10. Ans.(c)
Sol. Measuring the Speed of Light with Jupiter’s Moons. The first real measurement of the speed of light came about half a century later, in 1676, by a Danish astronomer, Ole Römer, working at the Paris Observatory.

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