# Physics Questions for Railway & SSC CGL Exam 2018: 9th November 2018

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Q1. Study of atmospheric  phenomena is called –
वायुमंडलीय घटनाओं के अध्ययन को क्या कहा जाता है?
(a) Astrology / ज्योतिष विज्ञान
(b) Meteorology / मौसम विज्ञान
(c) Seismology / भूकंप विज्ञान
(d) Astronomy / खगोल विज्ञान
Ans.(b)
Sol. Study of atmospheric phenomena is called Meteorology

Q2. A dentist’s mirror is a:
एक दंत चिकित्सक का दर्पण होता है:
(a) cylindrical mirror / बेलनाकार दर्पण
(b) plane mirror / समतल दर्पण
(c) convex mirror / उत्तल दर्पण
(d) concave mirror / अवतल दर्पण

Ans.(d)
Sol. Dentist’s mirror is concave. It is also called converging mirror. This mirror is used in reflecting telescopes, gather light from a small source, to form optical cavities etc.

Q3. The primary colours used in a colour TV are:
रंगीन टीवी में उपयोग किए जाने वाले प्राथमिक रंग हैं:
(a) Green, Yellow, Violet  / हरा, पीला, बैंगनी
(b) Violet, Red, Orange / बैंगनी, लाल, नारंगी
(c) Blue, Green, Red / नीला, हरा, लाल
(d) Blue, Green, Violet / नीला, हरा, बैंगनी

Ans.(c)
Sol. In electronic visual displays, the Primary colours normally used are red, green and blue. Primary colours are sets of colours that can be combined to make a useful range of colours.

Q4. A person is hurt on kicking a stone due to –
किसके कारण एक पत्थर पैर से मारने पर व्यक्ति को चोट लगती है?
(a) Inertia / जड़ता
(b) Velocity/ वेग
(c) Reaction / प्रतिक्रिया
(d) Momentum /संवेग

Ans.(c)
Sol. A person is hurt on kicking a stone due to reaction. Here Newton third law of motion is applied which states that every action has equal and opposite reaction.

Q5. The highest temperature attained by a super conductor is-
एक सुपर कंडक्टर द्वारा प्राप्त उच्चतम तापमान है –
(a) 24 K
(b) 138 K
(c) 150 K
(d) 300 K
(d) Biotin/ बायोटिन

Ans.(b)
Sol. Where as ordinary or metallic super conductors usually have transition temperature (temperature below which they are super conductive) below 30k and must be cooled using liquid helium in order to achieve super conductivity. High temperature super conductors have been observed with transition temperature as high as 138 K.

Q6. Total internal reflection can take place when light travels from:
कुल आंतरिक प्रतिबिंब तब हो सकता है जब प्रकाश ________ से यात्रा कर रहा है:
(a) Diamond to glass/डायमंड से ग्लास
(b) Water to glass/पानी से ग्लास
(c) Air to water/हवा से पानी
(d) Air to glass/हवा से ग्लास

Ans.(a)
Sol. Total internal reflection takes place when a ray of light is travelling from denser to thinner medium and angle of incidence is greater than the critical angle, the ray is completely reflected from surface and meet each other as if the surface is a mirror. So according to options, the situation of option (a) is correct where total internal reflection takes place, it is because diamond is denser than glass.

Q7. Which one of the following phenomenon is used in optical fibres?
ऑप्टिकल फाइबर में निम्न में से कौन सी घटना का उपयोग किया जाता है?
(a) Interference / इंटरफेरेंस
(b) Refraction / अपवर्तन
(c) Total internal reflection / कुल आंतरिक प्रतिबिंब
(d) Polarisation / ध्रुवीकरण
Ans.(c)
Sol. The optical fibre is a very thin strand of glass or plastic cable for transmitting light from one point to another. They work on he principle of total internal reflection. There is no loss of signal through an optical fibre.
Q8. Waves used for telecommunication are-
दूरसंचार के लिए किस प्रकार की तरंगों का उपयोग किया जाता हैं –
(a) Visible light /दृश्य प्रकाश
(b) Infrared/इन्फ्रारेड
(c) Ultraviolet/पराबैंगनी
(d) Microwave/माइक्रो तंरग
Ans.(d)
Sol. The microwaves are high-frequency signals in the 300 MHz to 300 Ghz range. The signals can carry thousands of channels at the same time, making it a very versatile communication system. Microwave is often used for point-to-point telecommunications. Today microwave is employed by telecommunication industry in the form of both terrestrial relays and satellite communication.
Q9. A dynamo which is said to general electricity actually acts as a
एक डाइनेमो जिसे जनरल इलेक्ट्रिसिटी कहा जाता है वह किस प्रकार कार्य करता है:
(a) Source of ions / आयनों का स्रोत
(b) Source of electric charge / विद्युत प्रभार का स्रोत
(c) Converter of energy / ऊर्जा का कनवर्टर
(d) Source of electrons / इलेक्ट्रॉनों का स्रोत
Ans.(c)
Sol. A dynamo, which is also known as an electrical generator produces direct current through a commutator. It is basically a device which converts mechanical rotation into electric current according to Faraday’s law.

Q10. The technique used to transmit audio signals in television broadcast is-
टेलीविज़न प्रसारण में ऑडियो सिग्नल संचारित करने के लिए किस तकनीक का इस्तेमाल होता है –
(a) Amplitude modulation/आयाम मॉड्‍यूलन
(b) Pulse code modulation/पल्स कोड मॉडुलेशन
(c) Frequency modulation/आवृति मॉडुलेशन
(d) Time dimension multiplication/समय आयाम बहुलीकरण
Ans.(c)
Sol. Television broadcasts emit two types of signals, audio and visual. These two signals require modulation to transmit both signals at the same time. Analog television requires transmission that uses specific modulation methods employing AM and FM signals in its transmission. Frequency modulation or FM is used for the audio part of the transmission. Amplitude modulation or AM is used in the video transmission. .

Q11. Weight of a person at a height of 2R from the centre of the earth, where R is the radius of the earth _______.
यदि R पृथ्वी की त्रिज्या है तो पृथ्वी के केंद्र से 2R की ऊंचाई पर एक व्यक्ति का वजन  _______ होगा.
(a) remains same/समान
(b) becomes half/आधा
(c) becomes twice/दोगुना
(d) becomes one­fourth/एक चौथाई
Ans.(d)
Sol. Weight of a person at a height of 2R from the centre of the earth, where R is the radius of the earth became one-fourth.
Q12. How can we measure specific gravity of milk?
हम दूध के विशिष्ट गुरुत्व को कैसे माप सकते हैं?
(a) Using a viscometer/एक विस्कोमेटर का उपयोग कर
(b) Using an odometer/एक ओडोमीटर का उपयोग कर
(c) Using a hygrometer/एक आर्द्रमीटर का उपयोग कर
(d) Using a hydrometer/एक हाइड्रोमीटर का उपयोग कर
Ans.(d)
Sol. A hydrometer is an instrument used to measure the specific gravity (or relative density) of liquids. It is also used to measure specific gravity of milk.

Q13. Who invented the nuclear reactor?
परमाणु रिएक्टर का आविष्कार किसने किया?
(a) Enrico Fermi/एनरिको फर्मी
(b) Adolf Gaston Eugen Fick/एडॉल्फ गेस्टोन यूजीन फिक
(c) Sandford Fleming/सैंडफोर्ड फ्लेमिंग
(d) Benoit Fourneyron/बेनोइट फोरनेरोन
Ans.(a)
Sol. Enrico Fermi was an Italian-American physicist and the creator of the world’s first nuclear reactor, the Chicago Pile-1. He has been called the “architect of the nuclear age” and the “architect of the atomic bomb”.
Q14. What is the angle between centripetal acceleration and tangential acceleration?
केन्द्रीकृत त्वरण और स्पर्शरेखा त्वरण के बीच कोण क्या है?
(a) 90°
(b) 45°
(c) 0°
(d) 180°
Ans.(a)
Sol. The angle between centripetal acceleration and tangential acceleration is 90°.
Q15. Rectifiers convert _____.
रेक्टीफाइर्स _____ को रूपांतिरत करते हैं.
(a) high voltage to low voltage/उच्च वोल्टेज को कम वोल्टेज में
(b) low voltage to high voltage/कम वोल्टेज को उच्च वोल्टेज में
(c) AC to DC/AC को DC में
(d) DC to AC/DC को AC में
Ans.(c)
Sol. A rectifier is an electrical device composed of one or more diodes that converts alternating current (AC) to direct current (DC).

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