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
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.
In two separate set-ups of the Young's double slit experiment, fringes of equal width are observed when lights of wavelengths in the ratio 1 : 2 are used. If the ratio of the slit separation in the two cases is 2 : 1, the ratio of the distances between the plane of the slits and the screen in the two set-ups is:
1. 4 : 1
2. 1 : 1
3. 1 : 4
4. 2 : 1
Which of the following statements indicates that light waves are transverse?
1. | Light waves can travel in a vacuum. |
2. | Light waves show interference. |
3. | Light waves can be polarized. |
4. | Light waves can be diffracted. |
By Huygen's wave theory of light, we cannot explain the phenomenon of:
1. | Interference |
2. | Diffraction |
3. | Photoelectric effect |
4. | Polarisation |
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. |
In Young's double-slit experiment, the slit separation is doubled. This results in:
1. | An increase in fringe intensity |
2. | A decrease in fringe intensity |
3. | Halving of the fringe spacing |
4. | Doubling of the fringe spacing |
In Young's double-slit experiment the light emitted from the source has = 6.5 × 10–7 m and the distance between the two slits is 1 mm. The distance between the screen and slits is 1 metre. Distance between third dark and fifth bright fringe will be:
1. 3.2 mm
2. 1.63 mm
3. 0.585 mm
4. 2.31 mm
Two superposing waves are represented by the following equations:
\({\mathrm{y}_1=5 \sin 2 \pi(10 \mathrm{t}-0.1 \mathrm{x}), \mathrm{y}_2=10 \sin 2 \pi(10 \mathrm{t}-0.1 \mathrm{x}).}\)
Ratio of intensities will be:
1. 1
2. 9
3. 4
4. 16
Unpolarized light of intensity 32 Wm–2 passes through three polarizers such that the transmission axes of the first and second polarizer make an angle of 30° with each other and the transmission axis of the last polarizer is crossed with that of the first. The intensity of the final emerging light will be:
1. 32 Wm–2
2. 3 Wm–2
3. 8 Wm–2
4. 4 Wm–2