# Which of the following sources gives the best monochromatic light? 1. a candle 2. a bulb 3. a mercury tube 4. a laser

Subtopic:  Young's Double Slit Experiment |
78%
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The wavefronts of a light wave travelling in vacuum are given by $$x+y+z=c$$. The angle made by the direction of propagation of light with the X-axis is:
1. $$0^{\circ}$$
2. $$45^{\circ}$$
3. $$90^{\circ}$$
4. $${\cos^{-1}\left({1}/{\sqrt{3}}\right )}$$

Subtopic:  Huygens' Principle |
From NCERT
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The wavefronts of light coming from a distant source of unknown shape are nearly:
1. plane
2. elliptical
3. cylindrical
4. spherical

Subtopic:  Huygens' Principle |
67%
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The inverse square law of intensity (i.e., the intensity $$\propto \frac{1}{r^2})$$ is valid for:
1. a point source
2. a line source
3. a plane source
4. a cylindrical source

Subtopic:  Huygens' Principle |
86%
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Two sources are called coherent if they produce waves:

 1 of equal wavelength 2 of equal velocity 3 having same shape of wavefront 4 having a constant phase difference

Subtopic:  Young's Double Slit Experiment |
85%
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When a drop of oil is spread on a water surface, it displays beautiful colours in daylight because of:

 1 dispersion of light 2 reflection of light 3 polarization of light 4 interference of light
Subtopic:  Superposition Principle |
57%
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Two coherent sources of different intensities send waves which interfere. The ratio of maximum intensity to the minimum intensity is $$25.$$ The intensities of the sources are in the ratio:
1. $$25:1$$
2. $$5:1$$
3. $$9:4$$
4. $$625:1$$

Subtopic:  Young's Double Slit Experiment |
80%
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The slits in a Young's double-slit experiment have equal width and the source is placed symmetrically with respect to the slits. The intensity at the central fringe is $$I_0.$$ If one of the slits is closed, the intensity at this point will be:
1. $$I_0$$
2. $$I_0/4$$
3. $$I_0/2$$
4. $$4I_0$$

Subtopic:  Young's Double Slit Experiment |
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A thin transparent sheet is placed in front of a Young's double-slit. The fringe-width will:
1. increase
2. decrease
3. remain same
4. become nonuniform

Subtopic:  Young's Double Slit Experiment |
60%
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If Young's double-slit experiment is performed in water,

1. the fringe width will decrease

2. the fringe width will increase

3. the fringe width will remain unchanged

4. there will be no fringe

Subtopic:  Young's Double Slit Experiment |
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