A diffraction pattern is observed using a beam of red light. What will happen if the red light is replaced by the blue light?
1. | No change takes place. |
2. | Diffraction bands become narrower. |
3. | Diffraction bands become broader. |
4. | Diffraction pattern disappears. |
The first diffraction minima due to a single slit diffraction is at for a light of wavelength \(5000~\mathring A.\) The width of the slit is:
1. 5 x 10-5 cm
2. 10 x 10-5 cm
3. 2.5 x 10-5 cm
4. 1.25 x 10-5 cm
What will be the angular width of central maxima in Fraunhofer diffraction when the light of wavelength \(6000~\mathring A\) is used and slit width is ?
1. 2 rad
2. 3 rad
3. 1 rad
4. 8 rad
Red light is generally used to observe diffraction patterns from a single slit. If the blue light is used instead of red light, then the diffraction pattern:
1. | will be clearer. |
2. | will contract. |
3. | will expand. |
4. | will not be visible. |
If we observe the single slit Fraunhofer diffraction with wavelength and slit width d, the width of the central maxima is 2. On decreasing the slit width for the same wavelength :
1. | θ increases. |
2. | θ remains unchanged. |
3. | θ decreases. |
4. | θ increases or decreases depending on the intensity of light. |
A parallel beam of monochromatic light of wavelength 5000 Å is incident normally on a single narrow slit of width 0.001 mm. The light is focused by a convex lens on a screen placed on the focal plane. The first minimum will be formed for the angle of diffraction equal to:
1. 0o
2. 15o
3. 30o
4. 60o
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. \(\text{sin}^{-1}\frac{1}{4}\)
The direction of the first secondary maximum in the Fraunhofer diffraction pattern at a single slit is given by:
(a is the width of the slit)
1.
2.
3.
4.
A single slit of width 0.1 mm is illuminated by a parallel beam of light of wavelength 6000 and diffraction bands are observed on a screen 0.5 m from the slit. The distance of the third dark band from the central bright band is:
1. 3 mm
2. 9 mm
3. 4.5 mm
4. 1.5 mm
A parallel beam of moving electrons is incident normal on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the slit is further narrowed, then which of the following statements is correct?
1. | The diffraction pattern is not observed on the screen in the case of electrons. |
2. | The angular width of the central maximum of the diffraction pattern will increase. |
3. | The angular width of the central maximum will decrease. |
4. | The angular width of the central maximum will remain the same. |