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प्रश्न
Name three properties of ultraviolet radiations which are similar to visible light.
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उत्तर
(a) Ultraviolet radiations travel in a straight line with a speed of 3 x `10^8` m in air (or vacuum).
(b) They obey the laws of reflection and refraction.
(c) They affect the photographic plate.
संबंधित प्रश्न
Name the rays or waves of highest frequency .
X-ray from a Coolidge tube is incident on a thin aluminium foil. The intensity of the X-ray transmitted by the foil is found to be I0. The heating current is increased to increase the temperature of the filament. The intensity of the X-ray transmitted by the foil will be
(a) zero
(b) < I0
(c) I0
(d) > I0
The wavelengths of Kα and Lα X-rays of a material are 21.3 pm and 141 pm respectively. Find the wavelength of Kβ X-ray of the material.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
Name the scientist who discovered radio waves
Name the part of the electromagnetic spectrum which is:
Suitable for radar systems used in aircraft navigation.
State two uses of infrared radiations.
Choose the correct option.
The EM wave emitted by the Sun and responsible for heating the Earth’s atmosphere due to greenhouse effect is
The area to be covered for T.V telecast is doubled then the height of transmitting antenna (T.V tower) will have to be:-
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?
