Minima in Diffraction

Q. Two sound sources each emitting waves of wavelength lymbda are fixed a given distance apart and an observer moves from one source to another with velocity u. Then number of beats heard by him per second is

Q. Light of the wavelength $550\text{nm}$ falls normally on a slit of width $22.0\times {10}^{-5}\text{cm}$. The angular position of the second minima from the central maxima will be :

1. $\frac{\pi }{8}$
2. $\frac{\pi }{12}$
3. $\frac{\pi }{6}$
4. $\frac{\pi }{4}$

Q. apparent wavelength of light coming from star moving away from earthis 0.02%more than its actual wavelength. velocity of star i

Q. Which of the following is the most precise device for measuring length?

1. A vernier callipers with 20 divisions on the sliding scale.
2. A screw gauge of pitch 1 mm and 100 divisions on the circular scale.
3. An optical instrument that can measure length to within a wavelength of light.
   
4. All instruments have same precision.
   

Q. How many wavelengths of Kr(86) arw there in one metre? (1)2348123.73 (2)1553164.13 (3)652189.63 (4)1650763.7

Q. A single slit illuminated by red light Of 6000 A° wavelength gives first order fraunhofer diffraction minima that aubtends angle of 4° with the axis calculate the slit width ​

Q. Light of the wavelength $550\text{nm}$ falls normally on a slit of width $22.0\times {10}^{-5}\text{cm}$. The angular position of the second minima from the central maxima will be :

1. $\frac{\pi }{8}$
2. $\frac{\pi }{12}$
3. $\frac{\pi }{6}$
4. $\frac{\pi }{4}$

Q. The separation between the consecutive dark fringes in a Young's double slit experiment is 1⋅0 mm. The screen is placed at a distance of 2⋅5 m from the slits and the separation between the slits is 1⋅0 mm. Calculate the wavelength of light used for the experiment.

Q.

A diffraction is obtained by using a beam of red light. What will happen if the red light is replaced by the blue light

[KCET 2000; BHU 2001]

1. Bands will be narrower

2. Bands become broader and further apart

3. No change will take place

4. Bands disappear

Q. Both light and sound waves produce diffraction. It is more difficult to observe the diffraction with light waves because

1. Light waves do not require medium
2. Wavelength of light waves is far smaller
3. Light waves are transverse
4. Speed of light is far greater

Q.

In Fresnel diffraction, if the distance between the disc and the screen is decreased, the intensity of central bright spot will

1. Increase

2. Decrease

3. Remain constant

4. None of these

Q. In a double slit experiment, the distance between the slits is $d$. The screen is at a distance $D$ from the slits. If a bright fringe is formed exactly in front of one of the slits its order is,

1. $\frac{d}{\lambda }$
   
2. $\frac{d^2}{2D\lambda }$
   
3. $\frac{{\lambda }^2}{dD}$
   
4. $\frac{D^2}{2\lambda D}$
   

Q. Find the angular separation between the consecutive bright fringes in a Young's double slit experiment with blue-green light of wavelength 500 nm. The separation between the slits is $2·0\times {10}^{-3}\mathrm{m}$.

Q. Using figure (22.1), find the relative luminosity of wavelength (a) 480 nm, (b) 520 nm (c) 580 nm and (d) 600 nm.

Q. A single slit diffraction pattern is formed with white light. For what wavelength of light, the third secondary maximum in the diffraction pattern coincides with the second secondary maximum of red light in the pattern. Take wavelength of red light as $6500\mathring{\text{A}}$?

1. $8840\mathring{\text{A}}$
2. $4120\mathring{\text{A}}$
3. $4640\mathring{\text{A}}$
4. $6420\mathring{\text{A}}$

Q. Two narrow slits emitting light in phase are separated by a distance of 1⋅0 cm. The wavelength of the light is $5·0\times {10}^{-7}\mathrm{m}$. The interference pattern is observed on a screen placed at a distance of 1⋅0 m. (a) Find the separation between consecutive maxima. Can you expect to distinguish between these maxima? (b) Find the separation between the sources which will give a separation of 1⋅0 mm between consecutive maxima.

Q. When light is refracted, which of the following does not change?
(a) Wavelength
(b) Frequency
(c) Velocity
(d) Amplitude

Q. Yellow light is used in single slit diffraction experiment with slit width 0.6 mm. If yellow light is replaced by X-rays then the pattern will reveal

[IIT-JEE (Screening) 1999; MP PMT 2002; KCET 2003]

1. That the central maxima is narrower

2. No diffraction pattern

3. More number of fringes

4. Less number of fringes