Here we are providing extra questions for class 12 physics. In this article we have covered class 12 physics chapter 10 Wave Optics. Different kind of questions are included to give students an idea about every possible question related to the chapter.
Table of Contents
Extra Questions for Class 12 Physics Chapter 10 Wave Optics
Very Short Answer Questions
Q.1. What type of wavefront will emerge from a (i) point source and (ii) distant light source?
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Answer: (i) Spherical wavefront (ii) Plane wavefront.Q.2. Why are coherent sources required to create interference of light?
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Answer: Coherent sources are required for sustained interference. If sources are incoherent, the intensity at a point will go on changing with time.Q.3. When monochromatic light travels from one medium to another, its wavelength changes but frequency remains the same. Explain.
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Answer: Frequency is the fundamental characteristic of the source emitting waves and does not depend upon the medium. Light reflects and refracts due to the interaction of incident light with the atoms of the medium. These atoms always take up the frequency of the incident light which forces them to vibrate and emit light of same frequency. Hence, frequency remains same.Q.4. Differentiate between a ray and a wavefront.
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Answer: A wavefront is a surface of constant phase. A ray is a perpendicular line drawn at any point on wavefront and represents the direction of propagation of the wave.Q.5. Light of wavelength 5000 Å propagating in air gets partly reflected from the surface of water. How will the wavelengths and frequencies of the reflected and refracted light be affected?
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Answer:
Q.6. What will be the effect on interference fringes if red light is replaced by blue light?
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Answer: We have, β=Dλ/d, the wavelength of blue light is less than that of red light; hence if red light is replaced by blue light, the fringe width decreases, i.e., fringes come closer.Fill in the Blanks
(i) _____ of light occurs when size of the obstacle of aperture is comparable to the wavelength of light.
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Answer: Diffraction(ii) In Young’s double slit experiment, the fringe width is given by _____.
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Answer: β=Dλ/d(iii) A beam of light is incident normally upon a polariser and the intensity of emergent beam is IO. The intensity of the emergent beam is found to be unchanged when the polariser is rotated about an axis perpendicular to the pass axis. Incident beam is _____ in nature.
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Answer: unpolarised(iv) The value of Brewster angle depends on the nature of the transparent refracting medium and the _____ of light used.
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Answer: wavelength(v) The phase difference between two waves in _____ interference is given as an even multiple of p.
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Answer: constructive(vi) Fringe width is different as separation between two consecutive _____ or _____.
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Answer: maxima, minima(vii) Continuous locus of oscillation with constant phase is called as _____.
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Answer: wave-front(viii) The tangent of angle of polarization as light ray travels from air to glass is equal to the refractive index. This law is called as _____.
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Answer: Brewster’s law(ix) At polarising angle the refracted and reflected rays are _____ to each other.
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Answer: perpendicular(x) In interference and _____, the light energy is redistributed, increases in one region and decreases in other.
