Fringe Width in YDSE

Q.

What is the antonym of dull?

Q. In the double-slit experiment, the distance of the first dark fringe from the central line is 1mm. The distance of the $2^{nd}$ bright fringe from the central line is

1. 6mm
2. 4mm
3. 12mm
4. 16mm

Q. In Young's double slit experiment, the two slits are illuminated by light of wavelength $5890\stackrel{\circ }{A}$ and the angular fringe width is ${0.2}^{\circ }$. If the whole apparatus is immersed in water, then the new angular fringe width will be (refractive index of water $=\frac{4}{3}$).

1. ${0.05}^{\circ }$
2. ${0.20}^{\circ }$
3. ${0.35}^{\circ }$
4. ${0.15}^{\circ }$

Q.

Two coherent light sources having intensities in the ratio $2\mathrm{x}$ produce an interference pattern. The ratio $\frac{({\mathrm{I}}_{\max }-{\mathrm{I}}_{\min })}{({\mathrm{I}}_{\max }+{\mathrm{I}}_{\min })}$ will be:

1. $2\sqrt{\frac{\left(2x\right)}{x+1}}$

2. $\sqrt{\frac{\left(2x\right)}{2x+1}}$

3. $2\sqrt{\frac{2x}{(2x+1)}}$

4. $\sqrt{\frac{\left(2x\right)}{x+1}}$

Q. Laser light of wavelength $630nm$ incident on a pair of slits produces an interference pattern in which the bright fringes are separated by $8.1mm$. A second light produces an interference pattern in which the fringes are separated by $7.2mm$. Then the wavelength of the second light will be

1. $600nm$
2. $560nm$
3. $660nm$
4. $500nm$

Q. A thin prism of angle ${15}^{\circ }$ made of glass of refractive index ${\mu }_1=1.5$ is combined with another prism of glass of refractive index ${\mu }_2=1.75$. The combination of the prism produces dispersion without deviation. The angle of the second prism should be:

1. ${12}^{\circ }$
2. ${10}^{\circ }$
3. $7^{\circ }$
4. $5^{\circ }$

Q. In YDSE, 12 fringes are observed to be formed in a certain segment of the screen when light of wavelength 600 nm is used. If the wavelength of light is changed to 400 nm, number of fringes observed in the same segment of the screen is given by.

1. 12
2. 18
3. 24
4. 30

Q. In a double – slit experiment, instead of taking slits of equal width, one slit is made twice as wide as the other. Then in the interference pattern

1. The intensities of both the maxima and the minima increase.
2. The intensity of the maxima decreases and that of the minima increases.
3. The intensity of the maxima increases and the minimum has zero intensity.
4. The intensity of the maxima decreases and the minima has zero intensity.

Q. In Young's double slit experiment the phase difference between the waves reaching the central fringe and fourth dark fringe will be

1. $6\pi$
2. $zero$
3. $4\pi$
4. $7\pi$

Q. A double slit is illuminated by light of wavelength $6000\stackrel{\circ }{A}$. The slits are $0.1cm$ apart and the screen is placed one meter away. Then the angular position of the ${10}^{th}$ maximum in radian and separation of the two adjacent minima will be respectively

1. $6\times {10}^{-3}\text{rad},0.6mm$
2. $3\times {10}^{-3}\text{rad},0.3mm$
3. $2\times {10}^{-3}\text{rad},0.2mm$
4. $4\times {10}^{-3}\text{rad},0.4mm$

Q. In a double slit experiment if light of wavelength $5000{\text{A}}^{\circ }$ is used then fringe width of $1\text{mm}$ is obtained. If now light of wavelength $6000{\text{A}}^{\circ }$ is used without altering the system then new fringe width will be :

1. $1\text{mm}$
2. $1.5\text{mm}$
3. $0.5\text{mm}$
4. $1.2\text{mm}$

Q.

Interference fringes are observed on a screen by illuminating two thin slits $1mm$ apart with a light source.

1. $2.05\mu m$

2. $2.87nm$

3. $2nm$

4. $1.27\mu m$

Q. In a Young’s double slit experiment the separation between the slits(d) = 0.5 mm and the wavelength used is $\lambda$ = 800 m. Find the total number of maxima that lies between two lines drawn symmetrically from the point right in the middle of the two slits.

1. 624
2. 625
3. 621
4. 640

Q. In a Young's double - slit experience, the slits are 2mm apart and are illuminated with a mixture of two wavelengths ${\lambda }_0=750nm$ and $\lambda =900nm$. The minimum distance from the common central bright fringe on a screen 2 m away from the slits where a bright fringe from one interference pattern coincides with a bright fringe from the other, is

1. 1.5mm
2. 3 mm
3. 4.5 mm
4. 6 mm

Q.

In Young's double slit experiment the slits are 0.5 mm apart and interference is observed on a screen placed at a distance of 100 cm from the slits. It is found that the 9th bright fringe and 3rd dark fringe from the centre are 9mm apart. What is the wavelength of light used?

1. 4000A
   

2. 6000A
   

3. 2000A
   

4. 8000A

Q. In an interference experiment, third bright fringe is obtained at a point on the screen with a light of $700\text{nm}$. What should be the wavelength of the light in order to obtain $5^{th}$ bright fringe at the same point?

1. $750\text{nm}$
2. $630\text{nm}$
3. $500\text{nm}$
4. $420\text{nm}$

Q. In the Young’s double slit experiment the resultant intensity at a point on the screen is 75% of the maximum intensity of the bright fringe. Then the phase difference between the two interfering rays at that point is

1. $\frac{\pi }{4}$
2. $\frac{\pi }{3}$
3. $\frac{\pi }{6}$
4. $\frac{\pi }{2}$

Q. In a Lloyd's single mirror experiment, the distance between the slit source and its image is $5mm$. The screen is at a distance of $1\text{m}$ from the source. The fringe width is observed to be $0.1mm$. Then the wavelength of light used is

1. $5460\stackrel{\circ }{A}$
2. $5000\stackrel{\circ }{A}$
3. $4000\stackrel{\circ }{A}$
4. $6460\stackrel{\circ }{A}$

Q. In a biprism experiment, when sodium light of wavelength $5890\stackrel{\circ }{\text{A}}$ is used, then twenty fringes are observed in $23\text{mm}$ distance on screen. In order to obtain $30$ fringes in $28\text{mm}$ of the interference pattern, one should use light of wavelength

1. $4700\stackrel{\circ }{\text{A}}$
2. $6161\stackrel{\circ }{\text{A}}$
3. $8835\stackrel{\circ }{\text{A}}$
4. $4381\stackrel{\circ }{\text{A}}$

Q. A beam of light consisting of two wavelengths, 650 nm and 520 nm, is used to obtain interference fringes in a Young’s double-slit experiment. (a) Find the distance of the third bright fringe on the screen from the central maximum for wavelength 650 nm. (b) What is the least distance from the central maximum where the bright fringes due to both the wavelengths coincide?

Q. An electron beam of energy 10 KeV is incident on metallic foil. If the interatomic distance is 0.55Å. Find the angle of diffraction.

1. $si{n}^{-1}\left(0.11\right)$
2. $si{n}^{-1}\left(0.22\right)$
3. $co{s}^{-1}\left(0.11\right)$
4. $co{s}^{-1}\left(0.22\right)$

Q. A thin prism made of glass is dipped in water, then minimum deviation with respect to air by it will be $[given{}^a{\mu }_g=\frac{3}{2}and{}^a{\mu }_w=\frac{4}{3}]$:

1. $\frac{1}{2}$
2. $\frac{1}{4}$
3. $\frac{1}{8}$
4. $\frac{1}{16}$

Q. Coherent electron beam is being used in YDSE. On increasing accelerating voltage, fringe width will

1. decrease
2. remain unchanged
3. increase
4. may increase or decrease

Q.

(a) The refractive index of glass is 1.5. What is the speed of light in glass? Speed of light in vacuum is 3.0 × 10⁸ m s⁻¹)

(b) Is the speed of light in glass independent of the colour of light? If not, which of the two colours red and violet travels slower in a glass prism?

Q. In Young's double slit interference experiment, the wavelength of light used is $6000\dot{A}$. If the path difference between waves reaching a point P on the screen is 1.5 microns, then at that point P

1. Second maxima occurs
2. Second minima occurs
3. Third minima occurs
4. Third maxima occurs

Q.

When light is incident on a soap film of thickness $5\times {10}^{-5}cm$, the wavelength of light reflected maximum in the visible region is $5320\stackrel{o}{A}$. Refractive index of the film will be ?

1. 1.22

2. 1.51

3. 1.83

4. 1.33

Q. A thin prism of glass is placed in air and water respectively. If $n_g=\frac{3}{2}$ and $n_w=\frac{4}{3}$, then the ratio of deviation produced by the prism for a small angle of incidence when placed in air and water separately is:

1. $9:8$
2. $4:3$
3. $3:4$
4. $4:1$

Q. A crown glass prism of angle $5^{\circ }$ is to be combined with a flint glass prism in such a way that the mean ray passes undeviated. The angle of flint glass prism is $A^{\prime }$ and angular deviation produced by the combination when white light goes through it is $\delta$. Refractive indices for red, yellow and violet light are $1.514,1.517$ and $1.523$ respectively for crown glass and $1.613,1.620$ and $1.632$ for flint glass. Then :

1. $A^{\prime }={8.4}^{\circ }$
2. $A^{\prime }={4.2}^{\circ }$
3. $\delta ={0.0348}^{\circ }$
4. $\delta ={0.0137}^{\circ }$

Q.

Why are the fringes straight and parallel?

Q.

In videos destructive interference is given (2n+ 1)lambda/2 where as in board book it is given by (2n - 1)lambda/2. Which of these is correct for destructive interference?