On a hot summer night, the refractive index of air is smallest near the ground and increases with height from the ground. When a light beam is directed horizontally, the Huygens' principle leads us to conclude that as it travels, the light beam:

1. becomes narrower
2. goes horizontally without any deflection
3. bends downwards
4. bends upwards

Subtopic:  Huygens' Principle |
Level 3: 35%-60%
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For a specific wavelength of 670 nm of light coming from a galaxy moving with velocity v, the observed wavelength is 670.7 nm. The value of v is:
1. 3 × 108 ms–1
2. 3 × 1010 ms–1
3. 3.13 × 105 ms–1
4. 4.48 × 105 ms–1
Subtopic:  Huygens' Principle |
Level 3: 35%-60%
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If a wave gets refracted into a denser medium, then which of the following is true?
1. wavelength, speed and frequency decrease.
2. wavelength increases, speed decreases and frequency remains constant.
3. wavelength and speed decrease but the frequency remains constant.
4. wavelength, speed and frequency increases.
Subtopic:  Huygens' Principle |
 81%
Level 1: 80%+
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