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प्रश्न
The outermost layer of the earth’s atmosphere is _______.
(A) stratosphere
(B) mesospher
(C) troposphere
(D) ionosphere
उत्तर
(d) Ionosphere
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संबंधित प्रश्न
(i) Which mode of propagation is used by shortwave broadcast services having frequency range from a few MHz upto 30 MHz? Explain diagrammatically how long distance communication can be achieved by this mode.
(ii) Why is there an upper limit to frequency of waves used in this mode?
What is space wave propagation?
What is ground wave communication?
In which directions do the electric and magnetic field vectors oscillate in an electromagnetic wave propagating along the x-axis?
The reflected waves from an ionosphere are _____.
(a) ground waves
(b) sky waves
(c) space waves
(d) very high-frequency waves
Four nuclei of an element undergo fusion to form a heavier nucleus, with release of energy. Which of the two – the parent or the daughter nucleus – would have higher binding energy per nucleon?
Describe briefly, by drawing suitable diagram, the space wave modes of propagation. Mention the frequency range of the waves in these modes of propagation ?
An em wave is travelling in a medium with a velocity `vecv =vhati` Draw a sketch showing the propagation of the em wave, indicating the direction of the oscillating electric and magnetic fields.
Mention three different modes of propagation used in communication system.
Propagation of Electromagnetic Wave?
Name the three different modes of propagation in a communication system. State briefly why do the electromagnetic waves with a frequency range from a few MHz up to 30 MHz can reflect back to the earth. What happens when the frequency range exceeds this limit?
Depict the fields diagram of an electromagnetic wave propagating along positive X-axis with its electric field along the Y-axis.
The length of half wave dipole at 30MH2 is
The radio wave of frequency 300 MHz to 3000 MHz be.long to
Polarization in e.m wave is caused by
Propagation constant of a transmission line is
The characteristic impedance of a coaxial cable is of the order of
What is the value of frequency at which an e.m wave must be propagated for the D-region of atmosphere to have a refractive index of 0.49? Electron density for D-region is 109 m-3:
Two waves A and B of frequencies 2 MHz and 3 MHz, respectively are beamed in the same direction for communication via sky wave. Which one of these is likely to travel longer distance in the ionosphere before suffering total internal reflection?
(i) The intensity of a light pulse travelling along a communication channel decreases exponentially with distance x according to the relation I = Ioe–αx, where Io is the intensity at x = 0 and α is the attenuation constant. Show that the intensity reduces by 75 per cent after a distance of `((In 4)/α)`
(ii) Attenuation of a signal can be expressed in decibel (dB) according to the relation dB = `10 log_10 (I/I_0)`. What is the attenuation in dB/km for an optical fibre in which the intensity falls by 50 per cent over a distance of 50 km?
