Wavefronts of Light

Q.

1. What is diffraction and its types?

Q. What is the shape of the wavefront in each of the following cases: (a) Light diverging from a point source. (b) Light emerging out of a convex lens when a point source is placed at its focus. (c) The portion of the wavefront of light from a distant star intercepted by the Earth.

Q.

Define coherent sources of light.

Q.

Which of the following is correct for light diverging from a point source?

1. The intensity decreases in proportion for the distance squared

2. The wave front is parabolic

3. The intensity at the wavelength does not depend on the distance

4. None of these

Q. Two coherent sources of equal intensities produces, intensity maximum of $100$ units. If the amplitude of one of the sources is reduced by $20\%.$ The new maximum intensity produced will be-

1. $100$
2. $81$
3. $89$
4. $60$

Q.

Why there is no backward wavefront?

Q.

Diffraction of light gives the information of

1. Transverse nature

2. Longitudinal nature

3. Both transverse and longitudinal

4. Neither transverse nor longitudinal

Q. Wavefronts can be a collection of points at

1. maximum displacement.
2. zero displacement.
3. either maximum or zero displacement.
4. any displacement, provided all of them are equal

Q.

Two plane wavefronts of light, one incident on a thin convex lens and another on the refracting face of a thin prism. After refraction at them, the emerging wavefronts respectively become

1. Plane wavefront and plane wavefront

2. Plane wavefront and spherical wavefront

3. Spherical wavefront and plane wavefront

4. Elliptical wavefront and spherical wavefront

Q. If a particle is projected with u = 30i cap + 40j cap.Find the displacement at 6 seconds

Q.

Which of the following undergoes largest diffraction?

1. Y^-rays

2. Radio waves

3. Ultraviolet light

4. Infra red light

Q. If the ratio of the intensity of two coherent sources is $4$. The ratio $\left[\frac{I_{max}-I_{min}}{I_{max}+I_{min}}\right]$ is equal to,

1. $4$
2. $\frac{4}{5}$
3. $\frac{3}{5}$
4. $9$

Q. A beam of light incident at angle 30° from surface. Diameter of beam is 2cm. Find diameter of refracted beam.

Q. A wavefront is an imaginary surface where :

1. phase changes at constant rate at all points along the surface
2. phase is same for all points
3. constant phase difference continuously changes between the points
4. phase changes all over the surface

Q. A particle moves a distance x in time t acc. to eq. X= 1/(t+5) The accelration of particle is proportional to

Q. What is wavefront? Describe Huygen's theory of secondary wavelets.

Q.

Which lens is used in Fresnel diffraction?

Q. What is wavefront of light waves?

Q. consider a point at the focal point of a converging lens .another convergent lens of short focal length is placed on the other side. .what is the nature of wavefront emerging from the final image?

Q. Plane wavefront is incident on a lens of focal length 20 cm. After refraction from the lens, nature of wavefront will be

1. Parabolic
2. Cylindrical
3. Spherical
4. Planar

Q. Resonance condition occurs when the frequency of external sources matches the natural frequency of the system.

1. False
2. True

Q. The phenomena which is not explained by Huygen's construction of the wavefront

1. diffraction
2. reflection
3. refraction
4. origin of spectra

Q. Match the following:
$\begin{array}{cc}\text{I. Planar Wavefronts}& \text{1. Water surface waves}\\ \text{II. Spherical Wavefronts}& \text{2. Waves in 3D produced by a point source}\\ \text{III. Circular Wavefronts}& \text{3. Waves in 3D produced by a point source infinitely far away}\end{array}$

1. I-3, II-1, III-2
2. I-1, II-2, III-3
3. I-3, II-2, III-1
4. I-2, II-1, III-3

Q. Wave front means:

1. all particles in it have same phase
2. few particles are in same phase, rest are in opposite phase
3. all particles have opposite phase of vibrations
4. all particles have random vibrations

Q. Light waves travel in a vacuum, along the $X-$axis. Which of the following may represent the wave fronts?

1. $x=c$
2. $y=c$
3. $z=c$
4. $x+y+z=c$

Q. What is a wavefront? How is it related to the rays of light ? What is the shape of a wavefront at a point faraway from the source of light ?

Q. Explain the construction of plane wavefront using Huygen's principle.

Q. The shape of wave front at a very large distance from source is ______

1. Circular
2. Cylindrical
3. Spherical
4. Plane

Q. Corpuscular theory of light was advanced by

1. Huygen
2. Newton
3. Maxwell
4. Hertz

Q. The radius of a wavefront as the waves propagate

1. decreases
2. increases
3. becomes zero
4. sometimes decreases and sometimes increases.