Laws of Refraction Using Huygens' Principle

Q.

Two transparent media A and B are separated by a plane boundary. The speed of light in medium A is $2.0\times {10}^8{\mathrm{ms}}^{-1}$ and in medium B is $2.5\times {10}^8{\mathrm{ms}}^{-1}$. The critical angle for which ray of light going from A to B suffers total internal reflection is

1. ${\sin }^{-1}\left(\frac{1}{2}\right)$

2. ${\sin }^{-1}\left(\frac{2}{5}\right)$

3. ${\sin }^{-1}\left(\frac{4}{5}\right)$

4. ${\sin }^{-1}\left(\frac{3}{5}\right)$

Q.

The intensity of light depends on:

1. amplitude

2. frequency

3. wavelength

4. none of the above

Q. The graph of $\sin i$ versus $\sin r$ for certain materials is given below. Identify the curve which is not possible for a given material. Assume the first medium to be air.
($i$ and $r$ are angle of incidence and refraction)

1. I
2. II
3. III
4. All the above

Q. Find the half angular width (in degrees) of the central bright maximum in the Fraunhofer diffraction pattern of a slit of width $12\times {10}^{-5}\text{cm}$ when the slit is illuminated by monochromatic light of wavelength $6000\mathring{A}$(integer only)

Q.

What do you mean by coherence? How are coherent sources produced in a laboratory?

Q.

How does the Huygens principle explain reflection?

Q.

What is plane polarised light?

Q. For a light of wavelength $800\text{nm}$, the limit of resolution of a telescope is found to be equal to $\alpha$. The limit of resolution for light of wavelength $400\text{nm}$ will be

1. $\alpha$
2. $\frac{\alpha }{2}$
3. $2\alpha$
4. $3\alpha$

Q.

Identify the correct statement from the following

1. A monochromatic ray of light after passing through the prism should create a spectrum of seven colors

2. Wave nature of light was proposed by Huygens

3. Huygen’s wave theory could not explain the phenomenon of reflection

4. The direction of the light ray and its wavefront are opposite

Q. Two points of differences between interference and diffraction

Q. A parallel beam of white light is incident normally on a water film of thickness $1.0\times {10}^{-4}\text{cm}$. Find the wavelength in the visible range $(400\text{nm}-700\text{nm})$ which are strongly transmitted by the film.

Refractive index of water, $\mu =1.33$.

1. $400\text{nm},550\text{nm},700\text{nm}$
2. $443\text{nm},532\text{nm},665\text{nm}$
3. $500\text{nm},600\text{nm},700\text{nm}$
4. $490\text{nm},560\text{nm},630\text{nm}$

Q.

What kinds of waves can show interference?

Q. In $\text{YDSE}$, dichromatic light of wavelengths $400\text{nm}$ and $560\text{nm}$ are used. The distance between the slits is $0.1\text{mm}$ and the distance between the plane of the slits and the screen is $1\text{m}$. The minimum distance between two successive regions of complete darkness is

1. $4\text{mm}$
2. $5.6\text{mm}$
3. $14\text{mm}$
4. $28\text{mm}$

Q.

Which of the phenomena cannot take place in sound waves?

1. Interference

2. Diffraction

3. Reflection

4. Polarization

Q. State Huygen's principle, Using this principle draw a diagram to show how a plane wave front incident at the interface of the two media gets refracted when it propagates from a rarer to a denser medium.Hence verify Snell's law of refraction .

Q.

difference between unpolarized and plane polarized light

Q. Figure shows plane waves refracted from air to water using Huygens' principle. $a,b,c,d$ and $e$ are the lengths on the diagram. The refractive index of water with respect to air is

1. $\frac{a}{e}$
2. $\frac{b}{e}$
3. $\frac{b}{d}$
4. $\frac{d}{b}$

Q.

For what distance ray optics is a good approximation when the aperture is 2 mm wide and the wavelength is 200 nm?

1. 20 m

2. 30 m

3. 50 m

4. 40 m

Q.

Obtain the conditions for constructive and destructive

Q. A parallel beam of light of wavelength $560\text{nm}$ falls on a thin film of oil $($refractive index $=1.4)$. What should be the minimum thickness of the film so that it strongly reflects the light?

1. $100\text{nm}$
2. $200\text{nm}$
3. $300\text{nm}$
4. $500\text{nm}$

Q. A diffraction pattern is produced by a single slit of width $0.5\text{mm}$ with the help of a convex lens of focal length $40\text{cm}.$ If the wavelength of light used is $5896\mathring{\text{A}}$. The distance of the first dark fringe from the axis will be

1. $0.047\text{cm}$
2. $0.047\text{m}$
3. $0.047\text{mm}$
4. $47\text{cm}$

Q.
A narrow beam of light is incident on thick plano convex lens of refractive index $\frac{3}{2}$ and thickness 5 cm as shown in figure. Radius of curved surface is R = 10 cm, then distance of point where beam converges from B is n cm, here n is (Round upto two digits after the decimal point.)

Q. Angular width $\left(\theta \right)$ of the central maximum, in a diffraction pattern of a single slit does not depend upon,

1. distance between slit and source
2. wavelength of light used
3. width of the slit
4. All of the above

Q. what is polarisation of light ? what types of waves show the property of polarisation ? name 2 methods to produce plane polarised light ?

Q. The ratio of de Brogile wave length of molcules of hydrogen and helium in two gas jars kept separately at temperatures of ${27}^{\circ }$ C and ${127}^{\circ }$ C respectively is

1. $\frac{2}{\sqrt{3}}$
2. $\frac{\sqrt{3}}{8}$
3. $\frac{2}{5}$
4. $\sqrt{\frac{8}{3}}$

Q. For what distance ray optics a good approximation when the aperture is 4 mm wide and the wavelength is 500nm?

1. $69m$
2. $16m$
3. $8m$
4. $32m$

Q. The Fresnel distance for aperture of $1\text{mm}$ using red light of wavelength $7000\mathring{A}$ is -

1. $1.428\text{m}$
2. $1.228\text{m}$
3. $1.828\text{m}$
4. $1.628\text{m}$

Q. In the figure, $PQ$ represents a plane wave front and $AO$ and $BP$ the corresponding extreme rays of monochromatic light of wavelength $\lambda$. The value of angle $\theta$ for which the ray $BP$ and the reflected ray $OP$ interfere constructively is given by

1. $cos\theta =\frac{\lambda }{2d}$
2. $cos\theta =\frac{\lambda }{4d}$
3. $sec\theta =\frac{\lambda }{3d}$
4. $sec\theta =\frac{2\lambda }{3d}$

Q. Find the half angular width (in degrees) of the central bright maximum in the Fraunhofer diffraction pattern of a slit of width $12\times {10}^{-5}\text{cm}$ when the slit is illuminated by monochromatic light of wavelength $6000\mathring{A}$(integer only)

Q. On the basis of Huygen's Wave theory of light, show that angle of reflection is equal to angle of incidence. You must draw a labelled diagram for this derivation.