NEET Wave Optics — Set 5

Question 1

What happens to the refracted ray when the angle of incidence exceeds the critical angle?

Accepted Answer

When the angle of incidence exceeds the critical angle, no refraction occurs, and the ray undergoes total internal reflection.

Question 2

What is the maximum intensity of light transmitted through three polaroids when the first and third are crossed, and the middle one is rotated, if the initial intensity is $ I_0 $?

Accepted Answer

For crossed polaroids, intensity after the second polaroid is $ I_0 \cos^2 \theta $, and after the third (at $ 90^\circ - \theta $) is $ I = I_0 \cos^2 \theta \sin^2 \theta = \frac{I_0}{4} \sin^2 2\theta $. Maximum occurs at $ \theta = 45^\circ $, so $ I = \frac{I_0}{4} $.

Question 3

What is the condition for the second secondary maximum in a single-slit diffraction pattern?

Accepted Answer

Secondary maxima occur at $ \theta \approx \frac{(n + \frac{1}{2})\lambda}{a} $. For the second secondary maximum, $ n = 2 $, $ \theta \approx \frac{5\lambda}{2a} $.

NEET Physics: Wave Optics — Practice Set 5

Q1. What happens to the refracted ray when the angle of incidence exceeds the critical angle?

Q2. What is the maximum intensity of light transmitted through three polaroids when the first and third are crossed, and the middle one is rotated, if the initial intensity is \( I_0 \)?

Q3. What is the condition for the second secondary maximum in a single-slit diffraction pattern?

Q4. What is the intensity of unpolarised light after passing through a single polaroid, if the initial intensity is \( I_0 \)?

Q5. What is the nature of unpolarized light?

Q6. What is the angular position of the second minimum in a single-slit diffraction pattern if the slit width is \( 8.0 \, \mu\text{m} \) and the wavelength is \( 640 \, \text{nm} \)?

Q7. Why does the diffraction pattern of a single slit show a central maximum broader than its secondary maxima?

Q8. What is the wavelength of light in a medium with refractive index 1.65 if its wavelength in air is \( 660 \, \text{nm} \)?

Q9. What is the phase difference corresponding to a path difference of \( 3\lambda/4 \) in a double-slit experiment?

Q10. What is the condition for total internal reflection to occur?