# Physics [Light] Questions for Railway ALP Stage-II Exam : 8th December 2018

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Q1.The final image in a simple microscope is
एक साधारण माइक्रोस्कोप में अंतिम छवि है
(a) real, diminished and in verted/ वास्तविक, छोटा और उल्टा
(b) real, magnified an erect/ वास्तविक, बड़ा और ऊर्ध्वशीर्ष
(c) virtual, magnified and erect/आभासी, बड़ा और ऊर्ध्वशीर्ष
(d) virtual, diminished and erect/ आभासी, छोटा और उल्टा
Ans.(c)
Sol. . The simple microscope is used for observing the magnified images of objects.
It consists of a converging lens of small focal length.
The final image formed by the simple microscope is virtual, magnified and erect as shown below.

Q2.The sharpness of a television image is termed as its
एक टेलीविजन छवि की तीक्ष्णता को किस रूप में जाना जाता है-
(a) clarity/ स्पष्टता
(b) colour/रंग
(c) resolution/रेसोलुशन
(d) graphics/ ग्राफिक्स

Ans.(c)
Sol. The sharpness of a television image is termed as its resolution. Resolution refers to the number of pixels in an image. Resolution is sometimes identified by the width and height of the image as well as the total number of pixels in the image.

Q3.Parabolic mirrors are used in
पैराबॉलिक दर्पण का उपयोग किसमें किया जाता है
(b) driving mirrors/ ड्राइविंग दर्पण
(c) dentists mirrors/ दंत चिकित्सक दर्पण
(d) shaving mirrors/ शेविंग दर्पण

Ans.(a)
Sol. Parabolic reflectors are used to collect energy from a distant source (for example sound waves or incoming star light). In optics, parabolic mirrors are used to gather light in reflecting telescopes and solar furnaces, and project a beam of light in flashlights, searchlights, stage spotlights, and car headlights.

Q4.It is dangerous to observe solar eclips with naked eyes, because
नग्न आंखों के साथ सौर ग्रहण देखना खतरनाक है, क्यूंकि
(a) infrared radiations from sum burn our retina/ सूर्य से इन्फ्रारेड विकिरण हमारे रेटिना को जला सकता है
(b) ultraviolet radiations from sun burn our retina/ सूर्य से पराबैंगनी विकिरण हमारे रेटिना को जला सकता है
(c) all radiations from sun initiate chemical reactions in eyes/ सूर्य से सभी विकिरण आंखों में रासायनिक प्रतिक्रियाएं करते हैं
(d) cosmic rays reach eyes more during the eclipse / ग्रहण के दौरान ब्रह्मांडीय किरणें आंखों तक पहुंचती हैं

Ans.(b)
Sol. But if you look at the partial eclipse, the portion of the sun that is visible can cause permanent damage to your eyes. Prolonged exposure to the sun’s light can cause “retinal burns.” Exposure can damage or even destroy cells in the retina.

Q5.The magnifying power of an astronomical telescope can be decreased by
एक खगोलीय दूरबीन की आवर्धक शक्ति को कैसे कम किया जा सकता है?
(a) decreasing the focal length of the eyepiece/ उपनेत्र की फोकल लंबाई घटा कर
(b) increasing the focal length of the eyepiece / उपनेत्र की फोकल लंबाई बड़ा कर
(c) increasing the focal length of the objective / वस्तु की फोकल लंबाई बड़ा कर
(d) None of the above/उपरोक्त में से कोई नहीं

Ans.(b)
Sol. The astronomical telescope is an optical instrument used to view the heavenly bodies such as moon, stars, planets and the distant objects. It consists of two convex lenses, an objective and an eye piece.
The magnifying power (M) of the astronomical telescope is given by
Angle subtended by the final
M=(image at eye)/(Angle subtended by the object at eye)
M=(Focal lenght of objective)/(Focal lenght of eyepiece)
This expression shows that in order to obtain high magnification, focal length of object must be large and that of eyepiece is small.

Q6.A microscope used in pathological laboratories forms
पैथोलॉजिकल प्रयोगशालाओं में उपयोग किये जाने वाला एक माइक्रोस्कोप कैसी छवि दिखता है?
(a) magnified, virtual, erect image/ बड़ा, आभासी, ऊर्ध्वशीर्ष
(b) diminished, real and erect image/छोटा,वास्तविक, सीधा
(c) magnified, virtual and inverted image/ बड़ा, आभासी, उल्टा
(d) diminished, virtual and erect image/ छोटा, आभासी, सीधा

Ans.(c)
Sol. A microscope used in pathological laboratories because magnified, virtual and inverted image

Q7.Optic fibers are used in
ऑप्टिक फाइबर का उपयोग किया जाता है
(a) CAT scans/ सीएटी स्कैन
(b) X-ray photos/ एक्स-रे फोटो
(c) ultrasound scans/ अल्ट्रासाउंड स्कैन
(d) high-speed communications / उच्च गति संचार
Ans.(d)
Sol. Optical fibres have become very important in high-speed communications, such as cable TV and high-speed broadband services. Information, in the form of pulses of light, is sent down bundles of optical fibres. Fibre optic cables are able to carry more signals than traditional copper cable telephone lines.

Q8.Myopia is the same as
मायोपिया किसके समान है-
(a) near sightedness/निकट दृष्टि दोष
(b) astigmatism / दृष्टिवैषम्य
(c) presbyopia/ प्रेस्बायोपिया
(d) long sightedness/दूर दृष्टि दोष
Ans.(a)
Sol. Nearsightedness ( myopia) is the most common form of visual defect. It is caused when the structures in the eye do not adequately focus the light that enters the eye onto the retina. It is also common for people to have both astigmatism and myopia at the same time.

Q9.Persistance of vision is the principle behind
दृष्टि की दृढ़ता किसके पीछे का सिद्धांत है-
(a) camera/ कैमरा
(b) spectroscope/ स्पेक्ट्रोस्कोप
(c) cinema/ सिनेमा
(d) periscope/ पेरिस्कोप
Ans.(c)
Sol. Persistence of vision refers to the optical illusion whereby multiple discrete images blend into a single image in the human mind and believed to be the explanation for motion perception in cinema and animated films.

Q10.Which of the following statements is true when we see ‘rainbow’?
जब हम ‘इंद्रधनुष’ देखते हैं तो निम्नलिखित में से कौन सा कथन सत्य है?
(a) We face sun and raindrops/ हमारा मुख सूरज और बारिश की बूंदों की ओर हैं
(b) The sun remains behind us and we face raindrops / सूर्य हमारे पीछे होता है और हमारा मुख बारिश की बूंदों की ओर होता हैं
(c) In light rainfall, we face sun/ हल्की बारिश में, हमारा मुख सूरज की ओर होता हैं
(d) The sky remains clear and the sun is at lower position in the sky/ आकाश स्पष्ट रहता है और सूर्य आकाश में निचली स्थिति में होता है
Ans.(b)
Sol. A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. The sun remains behind us and we face raindrops It takes the form of a multicoloured circular arc.

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