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प्रश्न
The small ozone layer on top of the stratosphere is crucial for human survival. Why?
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उत्तर
The small ozone layer on the top of the atmosphere is crucial for human survival because it absorbs harmful ultraviolet radiations present in sunlight and prevents it from reaching the Earth’s surface.
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.
Give a reason for the following:
It is necessary to use satellites for long-distance TV transmission. Why?
Why are infra-red waves often called heat waves? Explain.
What is the range of the wavelength of the following electromagnetic waves?
(a) Micro waves .
What do you understand by the invisible spectrum?
Name the waves produced by the changes in the nucleus of an atom.
Name two sources, each of infrared radiations and ultraviolet radiations.
Can a hydrogen atom emit characteristic X-rays?
If the potential difference applied to the tube is doubled and the separation between the filament and the target is also doubled, the cutoff wavelength
Moseley's Law for characteristic X-ray is √v = a(Z − b). Here,
An X-ray tube operates at 40 kV. Suppose the electron converts 70% of its energy into a photon at each collision. Find the lowest there wavelengths emitted from the tube. Neglect the energy imparted to the atom with which the electron collides.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
Suppose a monochromatic X-ray beam of wavelength 100 pm is sent through a Young's double slit and the interference pattern is observed on a photographic plate placed 40 cm away from the slit. What should be the separation between the slits so that the successive maxima on the screen are separated by a distance of 0.1 mm?
Name the scientist who discovered Infra-red waves
-
- Calculate the speed of the wave.
- Name the medium through which it is traveling.
State two uses of infrared radiations.
Answer briefly.
Does an ordinary electric lamp emit EM waves?
Answer briefly.
Give two uses of ultraviolet rays.
Name the e.m. waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves.
