Wave Optics - Live Session - NEET 2020Contact Number: 9667591930 / 8527521718

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In the Young's double - slit experiment, the interference pattern is found to have an

intensity ratio between bright and dark fringes, as 9. This implies that

(1) the intensities at the screen due to the two slits are 5 and 4 units, respectively

(2) the intensities at the screen due to the two slits are 4 and 1 unit, respectively

(3) the amplitude ratio is 3

(4) the amplitude ratio is 5

In Young's double - slit experiment, the separation between the slit is halved and the

distance between the slits and screen is doubled. The fringe width is

(1) unchaned (2) halved (3) double (4) quadrupled

In Young's experiment the wavelength of red light is $7.8\times {10}^{-5}$ cm and that of blue light

$5.2\times {10}^{-5}$ cm. The value of n for which (n+1)th blue bright band coincides with nth red band is

(1) 4 (2) 3 (3) 2 (4) 1

We shift Young's double slit experiment from air to water. Assuming that water is still and clear, it can be predicted that the fringe patter will

(1) remain unchanged (2) disappear

(3) shrink (4) be enlarged

In Young's double - slit interference experiment, the distance between two sources is 0.1 mm. The distance of the screen from the sources is 20 cm. Wavelength of light used is 5460 $\stackrel{0}{A}$. Then the angular position of the first dark fringe is?

(1) 0.08$\xb0$ (2) 0.16$\xb0$ (3) 0.20$\xb0$ (4) 0.32$\xb0$

In the Young's double slit experiment, the two equally bright slits are coherent, but of phase difference $\mathrm{\pi}/3$.If the maximum intensity on the screen is ${I}_{0}$, the intensity at the point on the screen equidistant from the slits is

(1) ${I}_{0}$ (2) ${I}_{0}$/2 (3) ${I}_{0}$/4 (4) 3${I}_{0}$/4

In an interference pattern produced by two identical slits, the intensity at the site of the central maximum is I. The intensity at the same spot when either of the two slits is closed is ${I}_{0}$. Therefore,

(1) I = ${I}_{0}$ (2) I = 2${I}_{0}$ (3) I = 4${I}_{0}$ (4) I = ${I}_{0}$ are not related to each other

White light is used to illuminate the two slits in a Young's doule - slit experiment. The separation between

slits is b and the screen is at a distance d (>> b) from the slits. At a point on the screen directly in from

of one of the slits, certain wavelengths are missing. Some of these missing wavelengths are

(1) $\lambda ={b}^{2}/d$ (2) $\lambda =2{b}^{2}/d$

(3) $\lambda ={b}^{2}/3d$ (4) $\lambda =2{b}^{2}/3d$

Four independent waves are expressed as ${y}_{1}={a}_{1}\mathrm{sin}\omega t,{y}_{2}={a}_{2}\mathrm{sin}2\omega t$,

${y}_{3}={a}_{3}\mathrm{cos}\omega tand{y}_{4}={a}_{4}\mathrm{sin}(\omega t+\pi /3)$. The interference is possible between

(1) (i) and (iii) (2) (i) and (iv)

(3) (iii) and (iv) (4) not possible at all

In a two slit experiment with monochromatic light fringes are obtained on a screen placed at some distance from the slits. If the screen is moved by $5\times {10}^{-2}$ m towards the slits, the change in fringe width is $3\times {10}^{-5}$ m. If separation between the slits is ${10}^{-3}$ m, the wavelength of light used is

(1) 6000 $\stackrel{0}{A}$ (2) 5000 $\stackrel{0}{A}$ (3) 3000 $\stackrel{0}{A}$ (4) 4500 $\stackrel{0}{A}$

Microwaves from a transmitter are directed normally towards a plane reflector. A detector moves along the normal to the reflector. Between positions of 14 successive maxima, the detector travels a distance of 0.14 m. The frequency of the transmitter is $\left(c=3\times {10}^{8}m/s\right)$

(1) $1.5\times {10}^{10}Hz$ (2) ${10}^{10}Hz$

(3) $3\times {10}^{10}Hz$ (4) $6\times {10}^{10}Hz$

To observe diffraction, the size of an obstacle

(1) should be of the same order as wavelength

(2) should be much larger than the wavelength

(3) have no relation to wavelength

(4) should be exactly $\lambda /2$

A diffraction pattern is obtained using a beam of red light. What happens if the red light is replaced

by blue light

(1) no change

(2) diffraction bands become narrower and crowded together

(3) bands become broader and farther apart

(4) bands disappear

The position of the direct image obtained at O, when a monochromatic beam of light is passed

througha plane transmission grating at normal incidence is shown in the figure. The diffracted images

A,B and C correspond to the first, second, and third order diffractions, respectively, when the

source is replaced by an another source of shorter wavelength

(1) all the four will shift in the direction C to O

(2) all the four will shift in the direction O to C

(3) the images C, B and A will shift toward O

(4) the images C, B and A will shift away from O

The main difference in the phenomenon of interference and diffraction is that

1. diffraction is due to the interaction of light from the same wavefront whereas interference is the interaction of waves from two isolated sources.

2. diffraction is due to the interaction of light from wavelength, whereas the interference is the interaction of two waves derived from the same source.

3. diffraction is due to the interaction of waves derived from the same source, whereas the interference is the bending of light from the same wavefront.

4. diffraction is caused by reflected waves from a source whereas interference caused is due to refraction of waves from a surface.

In the propagation of light waves, the angle between the plane of vibration and the plane of polarization is

(1) $0\xb0$ (2) $90\xb0$ (3) $45\xb0$ (4) 180$\xb0$

A beam of light AO is incident on a glass slab ($\mu $= 1.54) in a direction as shown in the figure. The

reflected ray OB is passed through a Nicol prism on viewing through a Nicol prism, we find on

rotating the prism that

(1) the intensity is reduced down to zero and remains zero

(2) the intensity reduces down some what and rises again

(3) there is no change in intensity

(4) the intensity gradually reduces to zero and then again increases

When unpolarized light is incident on a plane glass plate at Brewster's (polarizing) angle,

then which of the following statements is correct:

(1) reflected and refracted rays are completely polarized with their planes of

polarization parallel to each other

(2) reflected and refracted rays are completely polarized with their planes of

polarization perpendicular to each other

(3) the reflected light is plane-polarized but transmitted light is partially polarized

(4) the reflected light is partially polarized but refracted light is plane polarized

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