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प्रश्न
Answer briefly.
Name the most harmful radiation entering the Earth's atmosphere from outer space.
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उत्तर
Name the most harmful radiation entering the Earth's atmosphere from outer space – Ultraviolet radiation
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संबंधित प्रश्न
If the earth did not have an atmosphere, would its average surface temperature be higher or lower than what it is now?
Name two electromagnetic waves of frequency smaller than that of violet light. State one use of each.
What are ultraviolet radiations?
An electromagnetic wave has a frequency of 500 MHz and a wavelength of 60 cm.name the medium through which it is travelling
An X-ray beam can be deflected
Moseley's Law for characteristic X-ray is √v = a(Z − b). Here,
Cutoff wavelength of X-rays coming from a Coolidge tube depends on the
(a) target material
(b) accelerating voltage
(c) separation between the target and the filament
(d) temperature of the filament.
Find the energy, the frequency and the momentum of an X-ray photon of wavelength 0.10 nm.
(Use Planck constant h = 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
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 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.)
Name the part of the electromagnetic spectrum which is:
Produced by bombarding a metal target with high electrons.
Answer briefly.
Does an ordinary electric lamp emit EM waves?
X-rays, gamma rays and microwaves travelling in a vacuum have ______.
A bat moving at 10 ms−1 towards a wall sends a sound signal of 8000 Hz towards it. On reflection, it hears a sound of frequency f The value of f in Hz is close to (speed of sound = 320 ms−1)
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
A radio can tune to any station in the 7.5 mHz to 12 MHz band. What is corresponding wave length band.
If λv, λx and λm Am represents the wavelength of visible light, x-ray and microwaves respectively, then ______.
All components of the electromagnetic spectrum in a vacuum have the same ______
The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is ______.
Electromagnetic waves with wavelength
- λ1 is suitable for radar systems used in aircraft navigation.
- λ2 is used to kill germs in water purifiers.
- λ3 is used to improve visibility in runways during fog and mist conditions.
Identify and name the part of the electromagnetic spectrum to which these radiations belong. Also arrange these wavelengths in ascending order of their magnitude.
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?
Which radiation has the longest wavelength and lowest frequency in the electromagnetic spectrum?
Which group of activities uses radio waves?
Which devices commonly produce microwaves?
Which set consists of applications of infrared radiation?
Which part of the electromagnetic spectrum can the human eye detect?
Which are uses of gamma rays?
