NEET Wave Optics — Set 16

Question 1

Why does the wave theory of light predict that the speed of light decreases when it bends towards the normal during refraction?

Accepted Answer

The wave theory suggests that light slows down in a denser medium, causing the wavefront to bend towards the normal as it takes less time to travel a shorter path in the slower medium.

Question 2

Why does the wave theory struggle to explain the propagation of light through a vacuum?

Accepted Answer

Traditionally, waves require a medium to propagate, and the absence of a medium in a vacuum posed a challenge until the electromagnetic theory showed light as self-sustaining electric and magnetic fields.

Question 3

What is the phase difference corresponding to a path difference of $ 2\lambda $ in a double-slit experiment?

Accepted Answer

Phase difference $ \phi = \frac{2\pi}{\lambda} \Delta $. For $ \Delta = 2\lambda $, $ \phi = \frac{2\pi}{\lambda} \cdot 2\lambda = 4\pi $.

NEET Physics: Wave Optics — Practice Set 16

Q1. Why does the wave theory of light predict that the speed of light decreases when it bends towards the normal during refraction?

Q2. Why does the wave theory struggle to explain the propagation of light through a vacuum?

Q3. What is the phase difference corresponding to a path difference of \( 2\lambda \) in a double-slit experiment?

Q4. What is the resultant amplitude when two coherent waves of amplitude \( a \) interfere with a phase difference of \( \pi \)?

Q5. What is the speed of light in glass if its refractive index is 1.6 and the speed of light in vacuum is \( 3.0 \times 10^8 \, \text{m/s} \)?

Q6. What is the direction of energy propagation relative to the wavefront in a light wave?

Q7. In a double-slit experiment, if \( \lambda = 530 \, \text{nm} \), \( d = 0.15 \, \text{mm} \), and \( D = 1.8 \, \text{m} \), what is the fringe width?

Q8. What happens to the fringe width in a double-slit experiment if the slit separation is halved?

Q9. Why does the interference pattern from two slits require light to originate from a single source?

Q10. What is the shape of the wavefront from a distant star intercepted by Earth?