Unpolarised light is incident from the air on a plane surface of a material of refractive index $$\mu$$. At a particular angle of incidence $$i$$, it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation?

 1 the reflected light is polarised with its electric vector parallel to the plane of incidence. 2 the reflected light is polarised with its electric vector perpendicular to the plane of incidence. 3 $\mathrm{}$$$i = \text{sin}^{-1}\frac{1}{\mu}$$ 4 $$i = \text{tan}^{-1}\frac{1}{\mu}$$$\mathrm{}$
Subtopic:  Polarization of Light |
60%
From NCERT
NEET - 2018
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In Young's double-slit experiment, the separation $$d$$ between the slits is $$2~\text{mm}$$, the wavelength $$\lambda$$ of the light used is $$5896~\mathring{\text{A}}$$ and distance $$D$$ between the screen and slits is $$100~\text{cm}$$. It is found that the angular width of the fringes is $$0.20^{\circ}$$. To increase the fringe angular width to $$0.21^{\circ}$$ (with same $$\lambda$$ and $$D$$) the separation between the slits needs to be changed to:
1. $$1.8~\text{mm}$$
2. $$1.9~\text{mm}$$
3. $$2.1~\text{mm}$$
4. $$1.7~\text{mm}$$

Subtopic:  Young's Double Slit Experiment |
76%
From NCERT
NEET - 2018
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Young’s double-slit experiment is first performed in air and then in a medium other than air. It is found that the $$8^\mathrm{th}$$ bright fringe in the medium lies where the $$5^\mathrm{th}$$ dark fringe lies in the air. The refractive index of the medium is nearly:
1. $$1.59$$
2. $$1.69$$
3. $$1.78$$
4. $$1.25$$
Subtopic:  Young's Double Slit Experiment |
62%
From NCERT
NEET - 2017
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Two polaroids $$P_1$$ and $$P_2$$ are placed with their axis perpendicular to each other. Unpolarised light of intensity $$I_0$$ is incident on $$P_1$$. A third polaroid $$P_3$$ is kept in between $$P_1$$ and $$P_2$$ such that its axis makes an angle $$45^\circ$$ with that of $$P_1$$. The intensity of transmitted light through $$P_2$$ is:
1. $$\frac{I_0}{4}$$
2. $$\frac{I_0}{8}$$
3. $$\frac{I_0}{16}$$
4. $$\frac{I_0}{2}$$

Subtopic:  Polarization of Light |
67%
From NCERT
NEET - 2017
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An interference pattern is obtained with two coherent light sources of intensity ratio $$n.$$ In the interference pattern, the ratio $$\frac{I_{max}-I_{min}}{I_{max}+I_{min}}$$ will be:
1. $$\frac{\sqrt{n}}{n+1}$$
2. $$\frac{2\sqrt{n}}{n+1}$$
3. $$\frac{\sqrt{n}}{(n+1)^2}$$
4. $$\frac{2\sqrt{n}}{(n+1)^2}$$

Subtopic:  Superposition Principle |
74%
From NCERT
NEET - 2016
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A linear aperture whose width is $$0.02$$ cm is placed immediately in front of a lens of focal length $$60$$ cm. The aperture is illuminated normally by a parallel beam of wavelength $$5\times 10^{-5}$$ cm. The distance of the first dark band of the diffraction pattern from the centre of the screen is:
1. $$0.10$$ cm
2. $$0.25$$ cm
3. $$0.20$$ cm
4. $$0.15$$ cm

Subtopic:  Diffraction |
69%
From NCERT
NEET - 2016
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The intensity at the maximum in Young's double-slit experiment is $$I_0$$. The distance between the two slits is  $$d= 5\lambda$$,  where $$\lambda$$ is the wavelength of light used in the experiment. What will be the intensity in front of one of the slits on the screen placed at a distance $$D = 10 d$$?
1. $$\frac{I_0}{4}$$
2. $$\frac{3}{4}I_0$$
3. $$\frac{I_0}{2}$$
4. $$I_0$$

Subtopic:  Young's Double Slit Experiment |
58%
From NCERT
NEET - 2016
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In a diffraction pattern due to a single slit of width $$a$$, the first minimum is observed at an angle of $$30^{\circ}$$ when the light of wavelength $$5000~\mathring{\text{A}}$$ is incident on the slit. The first secondary maximum is observed at an angle of:
1. $$\text{sin}^{-1}\frac{2}{3}$$
2. $$\text{sin}^{-1}\frac{1}{2}$$
3. $$\text{sin}^{-1}\frac{3}{4}$$
4. $$\text{sin}^{-1}\frac{1}{4}$$

Subtopic:  Diffraction |
71%
From NCERT
NEET - 2016
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