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प्रश्न
Answer briefly.
Give two uses of ultraviolet rays.
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उत्तर
Uses:
- Ultraviolet rays destroy germs and bacteria and hence they are used for sterilizing surgical instruments and for purification of water.
- Used in burglar alarms and security systems.
- Used to distinguish real and fake gems.
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संबंधित प्रश्न
Name the parts of the electromagnetic spectrum which is
used to treat muscular strain.
Write in brief, how these waves can be produced.
What physical quantity is the same for X-rays of wavelength 10−10 m, red light of wavelength 6800 Å and radiowaves of wavelength 500 m?
If the earth did not have an atmosphere, would its average surface temperature be higher or lower than what it is now?
What do you understand by the statement, "Electromagnetic waves transport momentum"?
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) Gamma rays.
What is the range of the wavelength of the following electromagnetic waves?
(a) Micro waves .
Name the radiations of wavelength just longer than 8 × 10-7m.
Name the radiations of wavelength just shorter than 4 × 10-7 m.
Give one use of microwaves.
50% of the X-rays coming from a Coolidge tube are able to pass through a 0.1 mm thick aluminium foil. If the potential difference between the target and the filament is increased, the fraction of the X-rays passing through the same foil will be
The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiation,
(a) the intensity increases
(b) the minimum wavelength increases
(c) the intensity remains unchanged
(d) the minimum wavelength decreases.
Find the cutoff wavelength for the continuous X-rays coming from an X-ray tube operating at 30 kV.
(Use Planck constant h = 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
What potential difference should be applied across an X-ray tube to get X-ray of wavelength not less than 0.10 nm? What is the maximum energy of a photon of this X-ray in joule?
(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.
The stopping potential in a photoelectric experiment is linearly related to the inverse of the wavelength (1/λ) of the light falling on the cathode. The potential difference applied across an X-ray tube is linearly related to the inverse of the cutoff wavelength (1/λ) of the X-ray emitted. Show that the slopes of the lines in the two cases are equal and find its value.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
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- Calculate the speed of the wave.
- Name the medium through which it is traveling.
State two properties of infrared radiations which differ from visible light.
State three properties of infrared radiations similar to that of visible light.
Choose the correct option.
Earth’s atmosphere is richest in
Answer briefly.
Give two uses of radio waves.
For television broadcasting, the frequency employed is normally
Microwaves are electromagnetic waves with frequency in the range of.
The ozone layer absorbs
The frequency of e. m waves which is best suited .to observed of radius 3 × 10–4 his of the order of
Find the photon energy in units of ev for electromagnetic wave if waves length 40 m. Given h = 6.63 × 10–34 J.
One requires 11eV of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in ______.
Give any two uses of infrared waves.
In an atom X, electrons absorb the energy from an external source. This energy “excites” the electrons from a lower-energy level to a higher-energy level around the nucleus of the atom. When electrons return to the ground state, they emit photons.
The figure below is the energy level diagram of atom X with three energy levels, E1 = 0.00eV, E2 = 1.78eV and E3 = 2.95eV. The ground state is considered 0 eV for reference. The transition of electrons takes place between levels E1 and E2.
- What wavelength of radiation is needed to excite the atom to energy level E2 from E1?
- Suppose the external source has a power of 100 W. What would be the rate of photon emission?
