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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
Why are microwaves considered suitable for radar systems used in aircraft navigation?
Optical and radio telescopes are built on the ground but X-ray astronomy is possible only from satellites orbiting the earth. Why?
State an additional use of the X-rays waves
Name the radiations of wavelength just longer than 8 × 10-7m.
Give one use of ultraviolet radiation.
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).
Find the maximum potential difference which may be applied across an X-ray tube with tungsten target without emitting any characteristic K or L X-ray. The energy levels of the tungsten atom with an electron knocked out are as follows.
| Cell containing vacancy | K | L | M |
| Energy in keV | 69.5 | 11.3 | 2.3 |
The distance between the cathode (filament) and the target in an X-ray tube is 1.5 m. If the cutoff wavelength is 30 pm, find the electric field between the cathode and the target.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
For television broadcasting, the frequency employed is normally
