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प्रश्न
| Gamma rays | D | C | Visible light | B | A |
The above table shows different parts of the electromagnetic spectrum.
(a) Identify the parts of the spectrum marked as A, B, C and D.
(b) Which of the radiations A or B has the higher frequency?
(c) State two properties which are common to all parts of the electromagnetic spectrum.
(d) Name one source of each of the radiation of electromagnetic spectrum.
(e) Name one detector for each of the radiation.
(f) Name one use of each of the radiation.
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उत्तर
(a) A, B, C and D are microwaves, infrared waves, ultraviolet light and x-rays respectively.
(b) Radiations B (microwaves) have a higher frequency.
(c) Common properties of e-m spectrum:
(i) All electromagnetic waves travel with the same speed in vacuum (or air) which is equal to the speed of light i.e. 3 x 108 m/s.
(ii) These waves are unaffected by the electric and magnetic fields.
(d)
| Name of wave | Source |
| 1. Gamma rays | 1. cosmic rays |
| 2. X rays | 2. When highly energetic electrons are stopped by a heavy metal target of high melting point (x-ray tube) |
|
3. Ultraviolet |
3. Sunlight |
| 4. visible light | 4. White hot bodies |
|
5. Infrared waves |
5. Lamp with thoriated filament. |
| 6. Microwaves |
6. Electronic devices such as klystron tube. |
| 7. Radio waves | 7. Radio transmissions. |
(e)
| Name of waves | Detector |
| 1. Gamma rays | 1. Geiger tube |
| 2. X rays | 2. Photographic film coated with zinc sulphide. |
| 3. Ultraviolet | 3. Photographic plate |
| 4. visible light | 4. Eye photo cells |
| 5. Infrared waves | 5. Thermopile |
| 6. Microwaves | 6. Wave guide tubes |
| 7. Radio waves | 7. Earphone |
(f)
| Name of waves | Use |
| 1. Gamma rays | 1. Detecting flaws in metal casting. |
| 2. X rays | 2. Diffraction to find crystal structure |
| 3. Ultraviolet | 3. Burglar alarms |
| 4. visible light | 4. Photography |
| 5. Infrared waves | 5. Infra - red photography |
| 6. Microwaves | 6. Microwave cooking |
| 7. Radio waves | 7. Communication and navigation. |
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संबंधित प्रश्न
If the earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain.
Why are infra-red waves often called heat waves? Explain.
The wavelengths for the light of red and blue colours are roughly 7.8 × `10^7` m and 4.8 × `10^7` m respectively.
(a) Which colour has the greater speed in vacuum?
(b) Which colour has the greater speed in glass?
What is the range of the wavelength of the following electromagnetic waves?
(a) Infrared.
Iron emits Kα X-ray of energy 6.4 keV. Calculate the times taken by an iron Kα photon to cross through a distance of 3 km.
(Use Planck constant h = 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
The Kα X-rays of aluminium (Z = 13) and zinc (Z = 30) have wavelengths 887 pm and 146 pm respectively. Use Moseley's law √v = a(Z − b) to find the wavelengths of the Kα X-ray of iron (Z = 26).
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
The Kα and Kβ X-rays of molybdenum have wavelengths 0.71 A and 0.63 A respectively. Find the wavelength of Lα X-ray of molybdenum.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
How will you investigate the existence of the radiation beyond the red and violet extremes of the spectrum?
Solve the numerical problem.
Calculate the frequency in MHz of a radio wave of wavelength 250 m. Remember that the speed of all EM waves in a vacuum is 3.0 × 108 m/s.
