A green light is an incident from the water to the air-water interface at the critical angle \((\theta)\). Select the correct statement:
1. | The spectrum of visible light whose frequency is less than that of green light will come out to the air medium. |
2. | The spectrum of visible light whose frequency is more than that of green light will come out to the air medium. |
3. | The entire spectrum of visible light will come out of the water at various angles to the normal. |
4. | The entire spectrum of visible light will come out of the water at an angle of \(90^\circ\) to the normal. |
In figure, the optical fiber is \(l=2~\text{m}\) long and has a diameter of \(d=20~\mu\text{m}\). If a ray of light is incident on one end of the fiber at angle \(\theta_1=40^\circ\), the number of reflections it makes before emerging from the other end is close to: (refractive index of fiber is \(1.31\) and \(\sin 40^{\circ}=0.64\))
1. \(66000\)
2. \(55000\)
3. \(45000\)
4. \(57000\)