- 1(current)
Q. No.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 |
Two light waves having the same wavelength \(\lambda\) in vacuum are in phase initially. Then the first wave travels a path of length \(L_1\) through a medium of refractive index \(n_1\) while the second wave travels a path of length \(L_2\) through a medium of refractive index \(n_2\). The two waves are then combined to observe interference. The phase difference between the two waves, now, is:
1. \( \frac{2 \pi}{\lambda}\left(n_2 L_1-n_1 L_2\right)\)
2. \( \frac{2 \pi}{\lambda}\left(\frac{L_1}{n_1}-\frac{L_2}{n_2}\right) \)
3. \(\frac{2 \pi}{\lambda}\left(n_1 L_1-n_2 L_2\right) \)
4. \(\frac{2 \pi}{\lambda}\left(\frac{L_2}{n_1}-\frac{L_1}{n_2}\right) \)
1. 3 × 108 ms–1
2. 3 × 1010 ms–1
3. 3.13 × 105 ms–1
4. 4.48 × 105 ms–1
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.
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Q. No.
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