Advertisements
Advertisements
प्रश्न
Optical and radio telescopes are built on the ground but X-ray astronomy is possible only from satellites orbiting the earth. Why?
Advertisements
उत्तर
With reference to X-ray astronomy, X-rays are absorbed by the atmosphere. However, visible and radio waves can penetrate it. Hence, optical and radio telescopes are built on the ground, while X-ray astronomy is possible only with the help of satellites orbiting the Earth.
संबंधित प्रश्न
What role dose infra-red radiation play in maintain the Earth’s warmth
Name the electromagnetic radiations used for (a) water purification, and (b) eye surgery.
A wave has a wavelength of 10-3 nm. Name the wave.
Name two electromagnetic waves of frequency smaller than that of violet light. State one use of each.
The energy of a photon of a characteristic X-ray from a Coolidge tube comes from
A free atom of iron emits Kα X-rays of energy 6.4 keV. Calculate the recoil kinetic energy of the atom. Mass of an iron atom = 9.3 × 10−26 kg.
(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 Microwaves
-
- Calculate the speed of the wave.
- Name the medium through which it is traveling.
Name the part of the electromagnetic spectrum which is:
Suitable for radar systems used in aircraft navigation.
Name any two electromagnetic waves which have a frequency higher than that of violet light. State one use of each.
Give one use of electromagnetic radiations in Infrared radiation.
Choose the correct option.
Earth’s atmosphere is richest in
Answer briefly.
What is a carrier wave?
Microwaves are electromagnetic waves with frequency in the range of.
The area to be covered for T.V telecast is doubled then the height of transmitting antenna (T.V tower) will have to be:-
The frequency of e. m waves which is best suited .to observed of radius 3 × 10–4 his of the order of
Electromagnetic waves with wavelength
- λ1 is used in satellite communication.
- λ2 is used to kill germs in water purifies.
- λ3 is used to detect leakage of oil in underground pipelines.
- λ4 is used to improve visibility in runways during fog and mist conditions.
- Identify and name the part of electromagnetic spectrum to which these radiations belong.
- Arrange these wavelengths in ascending order of their magnitude.
- Write one more application of each.
Name the electromagnetic radiation whose frequency is 10 Hz.
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?
