# Physics [Wave & Light] For ALP Stage-II Quiz Exam : 28th December 2018

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Q1. White light is made up of seven colors. What is the method of separating the colors?
वाइट लाइट सात रंगों से बनी होती है. रंगों को अलग करने की विधि क्या है?
(a) By passing it through a prism / इसे प्रिज्म से पास कर के
(b) By filtration / निस्पंदन द्वारा
(c) Can’t be separated / अलग नहीं किया जा सकता
(d) Both (a) and (b)/(a) और (b) दोनों

Ans.(a)
Sol. The speed of light and its components vary inversely with the refractive index of the medium. Refraction is the deviation in the path of light when it travels from one optical medium to the other. Different wavelengths experience different degree of deviation. As a result, white light splits into 7 colours (VIBGYOR) on passing through the prism.

Q2. Retina of the eye is comparable to which of the following parts of a traditional camera?
आंख की रेटिना पारंपरिक कैमरे के निम्नलिखित हिस्सों से तुलनीय है?
(a) Film / फिल्म
(b) Lens  / लेंस
(c) Shutter  / शटर
(d) Cover / कवर

Ans.(a)
Sol. Retina of the eye is comparable to the film of a traditional camera. Retina is a film of nerve fibres. Image of the object is formed at retina just like camera film is used to see the images.

Q3. The filament of an electric bulb is made of
विद्युत बल्ब का फिलामेंट किस से बना होता है?
(a) copper/ तांबा
(b) Aluminum / अल्युमीनियम
(d) tungsten / टंगस्टन

Ans.(d)
Sol. Filament of bulb is made of tungsten because of its high melting point (3422°C), lowest vapour pressure and great tensile strength. Hence, when current passes, it gets heated to emit light but does not melt or expand.

Q4. Which mirror is used as a rear view mirror in the vehicles?
वाहनों में पीछे का दृश्य के लिए कौन सा दर्पण उपयोग किया जाता है-
(a) Plane / समतल
(b) Convex / उत्तल
(c) Concave / अवतल
(d) Plano concave / प्लेनो अवतल

Ans.(b)
Sol. Convex mirror is a diverging mirror used as a rear view mirror in the vehicles as it covers wide range of vehicles coming behind.

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

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

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. Ultrasonics are sound waves of frequency
अल्ट्रासोनिक ध्वनि तरंगों की आवृत्ति _________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
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
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
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
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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