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प्रश्न
Optical and radio telescopes are built on the ground but X-ray astronomy is possible only from satellites orbiting the earth. Why?
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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.
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संबंधित प्रश्न
Arrange the following radiations in the order of their increasing wavelength:
X-rays, infrared rays, ratio waves, gamma ray and microwaves.
What are ultraviolet radiations?
One of the following wavelengths is absent and the rest are present in the X-rays coming from a Coolidge tube. Which one is the absent wavelength?
The electric current in an X-ray tube (from the target to the filament) operating at 40 kV is 10 mA. Assume that on an average, 1% of the total kinetic energy of the electron hitting hte target are converted into X-rays.
(a) What is the total power emitted as X-rays and (b) how much heat is produced in the target every second?
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:
Suitable for radar systems used in aircraft navigation.
Define the term "Intensity" in the photon picture of electromagnetic radiation.
Give one use of electromagnetic radiations in Infrared radiation.
Answer briefly.
Why are microwaves used in radar?
Answer briefly.
Why light waves travel in a vacuum whereas sound waves cannot?
Answer briefly.
Give two uses of radio waves.
Answer briefly.
Name the most harmful radiation entering the Earth's atmosphere from outer space.
Answer briefly.
Why high-frequency carrier waves are used for the transmission of audio signals?
Solve the numerical problem.
Calculate the frequency in MHz of a radio wave of wavelength 250 m. Remember that the speed of all EM waves in a vacuum is 3.0 × 108 m/s.
X-rays, gamma rays and microwaves travelling in a vacuum have ______.
The ozone layer absorbs
Assertion (A): Ultraviolet radiations is scattered more as compared to the microwave radiations.
Reason (R): Wavelength of ultraviolet radiation is more than the wavelength of microwave radiation.
What happens when an electron collides with a positron?
