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प्रश्न
Name the scientist who discovered radio waves
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उत्तर
Marconi
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संबंधित प्रश्न
Identify the part of the electromagnetic spectrum which is suitable for radar system used in aircraft navigation.
What is the range of the wavelength of the following electromagnetic waves?
(a) Gamma rays.
Give the range of wavelength of the electromagnetic waves visible to us.
Name two sources, each of infrared radiations and ultraviolet radiations.
The wavelength of X-rays is 0.01 Å. Calculate its frequency. State the assumption made, if any.
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.)
Name the part of the electromagnetic spectrum which is:
Produced by bombarding a metal target with high electrons.
State two uses of infrared radiations.
All components of the electromagnetic spectrum in a vacuum have the same ______
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?
