In Young's double-slit experiment, the intensity of light at a point on the screen where the path difference is λ is K, (λ being the wavelength of light used). The intensity at a point where the path difference is λ/4 will be:
1. K
2. K/4
3. K/2
4. Zero
A parallel beam of fast-moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct?
1. | The angular width of the central maximum of the diffraction pattern will increase. |
2. | The angular width of the central maximum will decrease. |
3. | The angular width of the central maximum will be unaffected. |
4. | A diffraction pattern is not observed on the screen in the case of electrons. |
The main difference between the phenomena of interference and diffraction is that:
1. | diffraction is caused by reflected waves from a source whereas interference is caused due to the refraction of waves from a source. |
2. | diffraction is caused due to the interaction of waves derived from the same source, whereas interference is the bending of light from the same wavefront. |
3. | diffraction is caused due to the interaction of light from the same wavefront, whereas the interference is the interaction of two waves derived from the same source. |
4. | diffraction is caused due to the interaction of light from the same wavefront whereas interference is the interaction of waves from two isolated sources. |
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. |
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
In a double-slit experiment, the two slits are 1 mm apart and the screen is placed 1 m away. Monochromatic light of wavelength 500 nm is used. What will be the width of each slit for obtaining ten maxima of double-slit within the central maxima of a single-slit pattern?
1. 0.2 mm
2. 0.1 mm
3. 0.5 mm
4. 0.02 mm
At the first minimum adjacent to the central maximum of a single slit diffraction pattern, the phase difference between the Huygen’s wavelet from the edge of the slit and the wavelet from the midpoint of the slit is:
1. \(\frac{\pi}{4}~radian\)
2. \(\frac{\pi}{2}~radian\)
3. \(\pi~radian\)
4. \(\frac{\pi}{8}~radian\)
In Young's double-slit experiment, the separation d between the slits is 2 mm, the wavelength of the light used is 5896 Å and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20°. To increase the fringe angular width to 0.21° (with same and D) the separation between the slits needs to be changed to:
1. 1.8 mm
2. 1.9 mm
3. 2.1 mm
4. 1.7 mm
A linear aperture whose width is 0.02 cm is placed immediately in front of a lens of focal length 60 cm. The aperture is illuminated normally by a parallel beam of wavelength 5 x 10-5 cm. The distance of the first dark band of the diffraction pattern from the center of the screen is:
1. 0.10 cm
2. 0.25 cm
3. 0.20 cm
4. 0.15 cm
Two polaroids P1 and P2 are placed with their axis perpendicular to each other. Unpolarised light of intensity Io is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its axis makes an angle 45° with that of P1. The intensity of transmitted light through P2 is:
1.
2.
3.
4.