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Question : 11
Total: 12
(a) Electromagnetic waves of wavelengths lambda 1 , lambda 2 lambda 3
(i) Identify the electromagnetic waves, and
(ii) Write one source of each of them.
OR
(b) (i) State two conditions for two light sources to be coherent.
(ii) Give two points of difference between an interference pattern due to a double slit and a diffraction pattern due to a single slit.
(i) Identify the electromagnetic waves, and
(ii) Write one source of each of them.
OR
(b) (i) State two conditions for two light sources to be coherent.
(ii) Give two points of difference between an interference pattern due to a double slit and a diffraction pattern due to a single slit.
Solution:
(i) Wavelength λ 1 λ 2 λ 3
(ii) Source of microwaves: Klystron / magnetron valves.Source of ultraviolet waves: Movement of electrons in atoms from higher energy level to lower energy level.Source of infrared waves: Vibration of atoms and molecules.
OR
(i) Condition of two light sources to be coherent:
- The two sources of light must be derived from a single source.
- The source must be monochromatic in nature.
(ii) Difference between an interference pattern due to a double-slit and a diffraction pattern due to a single slit:
(ii) Source of microwaves: Klystron / magnetron valves.Source of ultraviolet waves: Movement of electrons in atoms from higher energy level to lower energy level.Source of infrared waves: Vibration of atoms and molecules.
OR
(i) Condition of two light sources to be coherent:
- The two sources of light must be derived from a single source.
- The source must be monochromatic in nature.
(ii) Difference between an interference pattern due to a double-slit and a diffraction pattern due to a single slit:
| Interference pattern | Diffraction pattern |
| Intensity is same for all maxima. | Intensity falls to successive maxima away from the normal. |
| Fringes are equally spaced. | Fringes are not equally spaced. |
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