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प्रश्न
What role dose infra-red radiation play in physical therapy?
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उत्तर
The molecules of CO₂, NH₃ and water which are present in most materials absorb infrared waves. Due to this, the molecules heat and heat their surroundings. Hence, their thermal motion increases. Medical instruments, such as the infrared lamp which is used in physiotherapy, work on this principle.
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संबंधित प्रश्न
Give a reason for the following:
It is necessary to use satellites for long-distance TV transmission. Why?
Name the subjective property of light related to its wavelength.
Name two electromagnetic waves of frequency smaller than that of violet light. State one use of each.
One of the following wavelengths is absent and the rest are present in the X-rays coming from a Coolidge tube. Which one is the absent wavelength?
Mark the correct options.
(a) An atom with a vacancy has smaller energy that a neutral atom.
(b) K X-ray is emitted when a hole makes a jump from the K shell to some other shell.
(c) The wavelength of K X-ray is smaller than the wavelength of L X-ray of the same material.
(d) The wavelength of Kα X-ray is smaller than the wavelength of Kβ X-ray of the same material.
For a given material, the energy and wavelength of characteristic X-rays satisfy
(a) E(Kα) > E(Kβ) > E(Kγ)
(b) E(Mα) > E(Lα) > E(Kα)
(c) λ(Kα) > λ(Kβ) > λ(Kγ)
(d) λ(Mα) > λ(Lα) > λ(Kα).
The Kβ X-rays from certain elements are given below. Draw a Moseley-type plot of √v versus Z for Kβ radiation.
| Element | Ne | P | Ca | Mn | Zn | Br |
| Energy (keV) | 0.858 | 2.14 | 4.02 | 6.51 | 9.57 | 13.3 |
Electromagnetic waves with wavelength
- λ1 is used in satellite communication.
- λ2 is used to kill germs in water purifies.
- λ3 is used to detect leakage of oil in underground pipelines.
- λ4 is used to improve visibility in runways during fog and mist conditions.
- Identify and name the part of electromagnetic spectrum to which these radiations belong.
- Arrange these wavelengths in ascending order of their magnitude.
- Write one more application of each.
Identify the electromagnetic wave whose wavelength range is from about 10-3 m to about 10-1 m. Write one use of this.
Name the electromagnetic radiation that has been used in obtaining the image below.
