रेलवे बोर्ड अपने उम्मीदवारों के लिए भव्य और प्रतिष्ठित कार्य पदों की पेशकश करता है. और हर साल ऐसा नहीं होता है कि हमें रेलवे की ओर से अधिसूचना मिलती है. लेकिन वर्तमान वर्ष 2019 आपके लिए बहुत सुखद वर्ष है क्योंकि इसमें लगभग 1,27,278 सीटों को वैध उम्मीदवारों द्वारा भरा जाएगा. आपके पास बहुत अच्छा अवसर है और आपको इसे एक बेहतर रणनीति से प्राप्त करना होगा.


Q1. A cut diamond sparkles because of its
एक तराशा हुआ हीरा किस की वजह से चमकता है-
(a) hardness / कठोरता
(b) high refractive index / उच्च अपवर्तक सूचकांक
(c) emission of light by the diamond / हीरे द्वारा प्रकाश का उत्सर्जन
(d) absorption of light by the diamond / हीरे द्वारा प्रकाश का अवशोषण
Show Answer

Ans.(b)
Sol. Diamonds have a very high refractive index (about 2.42 compared to about 1.5 for glass). The amount of light reflected at an air/other material interface is related to the refractive index charge at the interface and the bigger the refractive index change, the more light is reflected. Thus, diamond reflects large amount of light and therefore, sparkles more.
Q2. Butter paper is an example of …….. object.
बटर पेपर ________ ऑब्जेक्ट का एक उदाहरण है
(a) a transparent / पारदर्शक
(b) a translucent / पारदर्शी
(c) an opaque / अपारदर्शी
(d) a luminous / प्रकाशमान
Show Answer

Ans.(b)
Sol. Butter paper is a translucent object as it allows light to pass through it partially, thus not providing clear vision. While, a transparent substance allows light to pass through it completely providing a clear vision. Whereas, an opaque substance is impenetrable to light. On the other hand, luminous objects emit their own light.

Q3. A vibrating body
एक कांपता हुआ शरीर
(a) will always produce sound / हमेशा ध्वनि उत्पन्न करेगा
(b) may or may not produce sound if the amplitude of vibration is low / कंपन का आयाम कम होने पर ध्वनि उत्पन्न कर भी सकता है और नहीं भी
(c) will produce sound which depends upon frequency / ध्वनि उत्पन्न करेगा जो आवृत्ति पर निर्भर करता है
(d) None of these /इनमें से कोई नहीं
Show Answer

Ans.(c)
Sol. A vibrating body will produce sound which is dependent upon the frequency. Sounds of frequencies less than about 20 vibrations per second (20 Hz) cannot be detected by the human ear. Such sounds are called inaudible. On the higher side, sounds of frequencies higher than about 20,000 vibrations per second (20 kHz) are also not audible to the human ear.
Q4. The special technique used in ships to calculate the depth of ocean beds is
महासागरों की गहराई की गणना के लिए जहाजों में प्रयुक्त विशेष तकनीक है
(a) LASER
(b) SONAR
(c) sonic boom / ध्वनि बूम
(d) reverberation/ प्रतिध्वनि
Show Answer
Ans.(b)
Sol. SONAR or sound Navigation and Ranging is helpful for exploring and mapping the ocean because sound waves travel farther in the water than do radar and light waves. These also determine the time between the emission of sound pulse and its reception, the transducer can determine the range and orientation of the object.
While, LASER is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Whereas, sonic boom is the sound associated with the shock waves created by an object travelling through the air faster than the speed of sound. On the other hand, reverberation is the prolongation of a sound.
Q5. The reason of mirage is
मिराज का कारण है:
(a) Interference of light / प्रकाश का हस्तक्षेप
(b) Diffraction of light / प्रकाश का विवर्तन
(c) Polarization of light / प्रकाश का ध्रुवीकरण
(d) Total internal reflection of light / प्रकाश का कुल आंतरिक प्रतिबिंब
Show Answer

Ans.(d)
Sol. Mirage is an optical illusion. The reason of mirage is total internal reflection of light. In summer air near the ground is hotter and hence rarer than the air above which is responsible for TIR, hence, mirage is formed.
Q6. The color of light is determined by its
प्रकाश का रंग किसके द्वारा निर्धारित किया जाता है
(a) Amplitude/आयाम
(b) Wavelength/तरंग दैर्ध्य
(c) Intensity/तीव्रता
(d) Velocity/वेग
Show Answer

Ans.(b)
Sol. Wavelength is the distance between two points of the wave in the same phase. It is related to frequency and energy of the radiations. It helps in determining colour of light waves. The wavelength of light visible to eye falls between 400nm to 800nm.


Q7. Ultrasonic are sound waves of frequency
अल्ट्रासोनिक ध्वनि तरंगों की आवृत्ति ________ होती हैं.
(a) Greater than 20,000 Hz /20,000 हर्ट्ज से अधिक
(b) Less than 10,000 Hz / 10,000 हर्ट्ज से कम
(c) Equal to 1000 Hz /1000 हर्ट्ज के बराबर
(d) None of these / इनमे से कोई नहीं
Show Answer

Ans.(a)
Sol. Ultrasonics are sound waves of frequency greater than 20,000 Hz. The frequency range 20Hz to 20,000 Hz is human audible range of frequency.


Q8. Laser is a device for producing
लेजर _________ उत्पादन के लिए एक उपकरण है
(a) spontaneous radiation / सहज विकिरण
(b) dispersed radiation / फैलाव विकिरण
(c) scattered radiation / बिखरे हुए विकिरण
(d) stimulated radiation / उत्तेजित विकिरण
Show Answer

Ans.(d)
Sol. Laser (Light Amplification by Stimulated Emission of Radiation) is a device for producing stimulated radiation. In stimulated radiation, an incoming photon of a specific frequency can interact with an excited atomic electron causing creation of a new photon identical in all respect to the incident photon.
As a result, two similar waves (original incident wave and the newly formed one) constructively interfere, leading to a more intense wave.

Q9. What type of electromagnetic radiation is used in the remote control of a television?
टेलीविज़न के रिमोट कंट्रोल में किस प्रकार के विद्युत चुम्बकीय विकिरण का उपयोग किया जाता है?
(a) Infrared / इन्फ़रा रेड
(b) Ultraviolet / पराबैंगनी
(c) Visible / दर्शनीय
(d) None of these /इनमें से कोई नहीं
Show Answer

Ans.(a)
Sol. Infrared is used in the remote control of a television. It has wavelength greater than visible light (>800nm) which is invisible to human eye but can be felt as heat.

Q10. A 100 watt bulb is kept switched ON for four hours. The units of electrical energy consumed is
4 घंटे के लिए 100 वाट का एक इलेक्ट्रिक बल्ब का उपयोग किया जाता है. उपयोग की गई बिजिली की ऊर्जा की इकाई है:
(a) 400 unit / इकाई
(b) 25 unit / इकाई
(c) 4 unit / इकाई
(d) 0.4 unit / इकाई
Show Answer

Ans.(d)
Sol. One unit of electrical energy
= 1 kwh.
= 1 kilo watt hour
= 100/1000 kilo watt × 4 hour
= 0.4 unit


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