Angular Position of Fringes in Diffraction

Q. Visible light of wavelength $6000\times {10}^{-8}cm$ falls normally on a single slit and produces a diffraction pattern. It is found that the second diffraction minima is at ${60}^o$ from the central maxima. If the first minimum is produced at ${\theta }_1$, then ${\theta }_1$ is close to

1. ${20}^o$
2. ${30}^o$
3. ${45}^o$
4. ${25}^o$

Q. Light of wavelength $6000\stackrel{\circ }{A}$ is incident normally on a slit of width $24\times {10}^{-5}\text{cm}$. What is the angular position of second minimum from central maximum?

1. ${30}^{\circ }$
2. ${45}^{\circ }$
3. ${60}^{\circ }$
4. ${15}^{\circ }$

Q. Radius of $1^{\text{st}}$ dark ring of Fraunhofer diffraction pattern produced by a circular aperture of radius $0.02\text{cm}$ at focal plane of convex lens of focal length $20\text{cm}$ and by light of wavelength $\lambda =600\text{nm}$ is

1. 0.7 mm
2. 0.36 mm
3. 1.3 mm
4. 2 cm

Q. Visible light of wavelength $6000\times {10}^{-8}cm$ falls normally on a single slit and produces a diffraction pattern. It is found that the second diffraction minima is at ${60}^o$ from the central maxima. If the first minimum is produced at ${\theta }_1$, then ${\theta }_1$ is close to

1. ${20}^o$
2. ${30}^o$
3. ${45}^o$
4. ${25}^o$

Q. Visible light of wavelength $6000\times {10}^{-8}cm$ falls normally on a single slit and produces a diffraction pattern. It is found that the second diffraction minima is at ${60}^o$ from the central maxima. If the first minimum is produced at ${\theta }_1$, then ${\theta }_1$ is close to

1. ${20}^o$
2. ${30}^o$
3. ${45}^o$
4. ${25}^o$

Q.

Angular width (b) of central maximum of a diffraction pattern on a single slit does not depend upon

[DCE 2000; 01]

1. Distance between slit and source

2. Wavelength of light used

3. Width of the slit

4. Frequency of light used

Q. Light of wavelength 6328 $\dot{A}$ is incident on a slit having a width of 0.2 mm. The width of the central maximum, measured from minimum to minimum of the diffraction pattern on a screen 9.0 metre away will be about:

1. 0.36 degrees
2. 0.18 degrees
3. 0.72 degrees
4. 0.09 degrees

Q.

Angular width (b) of central maximum of a diffraction pattern on a single slit does not depend upon

[DCE 2000; 01]

1. Distance between slit and source

2. Wavelength of light used

3. Width of the slit

4. Frequency of light used

Q. Radius of $1^{\text{st}}$ dark ring of Fraunhofer diffraction pattern produced by a circular aperture of radius $0.02\text{cm}$ at focal plane of convex lens of focal length $20\text{cm}$ and by light of wavelength $\lambda =600\text{nm}$ is

1. 0.7 mm
2. 0.36 mm
3. 1.3 mm
4. 2 cm

Q. Consider the diffraction pattern obtained with a single slit, illuminated at normal incidence. At the angular position of the first diffraction minimum, the phase difference (in radians) between the wavelets from the opposite edges of the slit is:

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