NEET Wave Optics — Set 13

Question 1

What allows light to continue propagating as a transverse wave after passing through a polaroid?

Accepted Answer

The transverse nature of light, with electric fields oscillating perpendicular to propagation, is preserved, but restricted to the polaroid’s pass-axis direction.

Question 2

What is the intensity at a point in a double-slit experiment where the path difference is $ 3\lambda/4 $, if the maximum intensity is $ 4I_0 $?

Accepted Answer

Intensity $ I = 4I_0 \cos^2(\phi/2) $, where $ \phi = \frac{2\pi}{\lambda} \Delta $. For $ \Delta = \frac{3\lambda}{4} $, $ \phi = \frac{2\pi}{\lambda} \cdot \frac{3\lambda}{4} = \frac{3\pi}{2} $, $ I = 4I_0 \cos^2\left(\frac{3\pi}{4}\right) = 4I_0 \left(\frac{\sqrt{2}}{2}\right)^2 = 4I_0 \times \frac{1}{2} = 2I_0 $.

Question 3

In a double-slit experiment, if $ \lambda = 520 \, \text{nm} $, $ d = 0.4 \, \text{mm} $, and $ D = 2.5 \, \text{m} $, what is the fringe width?

Accepted Answer

Fringe width $ \beta = \frac{\lambda D}{d} $. $ \lambda = 5.2 \times 10^{-7} \, \text{m} $, $ d = 4.0 \times 10^{-4} \, \text{m} $, $ D = 2.5 \, \text{m} $. $ \beta = \frac{5.2 \times 10^{-7} \times 2.5}{4.0 \times 10^{-4}} = 3.25 \times 10^{-3} \, \text{m} = 3.25 \, \text{mm} $.

NEET Physics: Wave Optics — Practice Set 13

Q1. What allows light to continue propagating as a transverse wave after passing through a polaroid?

Q2. What is the intensity at a point in a double-slit experiment where the path difference is \( 3\lambda/4 \), if the maximum intensity is \( 4I_0 \)?

Q3. In a double-slit experiment, if \( \lambda = 520 \, \text{nm} \), \( d = 0.4 \, \text{mm} \), and \( D = 2.5 \, \text{m} \), what is the fringe width?

Q4. What explains the presence of a central bright fringe in a single-slit diffraction pattern?

Q5. What is the critical angle for light passing from a medium with refractive index 1.9 to air (refractive index 1.0)?

Q6. What is the intensity at a point in a double-slit experiment where the phase difference is \( 2\pi \), if the maximum intensity is \( 4I_0 \)?

Q7. What property of light waves explains why the frequency remains constant when light refracts into a denser medium?

Q8. What is the angular position of the first secondary maximum in a single-slit diffraction pattern if the slit width is \( 9.0 \, \mu\text{m} \) and the wavelength is \( 450 \, \text{nm} \)?

Q9. In a double-slit experiment, if \( \lambda = 580 \, \text{nm} \), \( d = 0.2 \, \text{mm} \), and \( D = 1.0 \, \text{m} \), what is the distance of the fourth bright fringe from the central maximum?

Q10. What explains the absence of a refracted ray when the angle of incidence exceeds the critical angle?