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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
Write a short note on surface wave propagation of electromagnetic waves.
(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?
Derive an expression for the maximum line of sight distance between two antennas for space wave propagation.
What is ground wave communication?
Is it necessary for a transmitting antenna to be at the same height as that of the receiving antenna for line-of-sight communication? A TV transmitting antenna is 81m tall. How much service area can it cover if the receiving antenna is at the ground level?
Explain why ground wave communication mode cannot be used for long-distance communication using high frequencies
What is space wave propagation? Which systems of communication use space waves? What is 'radio horizon' of a transmitting antenna of height h? Why is space wave propagation suitable for frequencies above 40 MHz?
Explain why this mode cannot be used for long distance communication using high frequencies.
Is it necessary for a transmitting antenna to be at the same height as that of receiving antenna for LOS communication ?
Mention three different modes of propagation used in communication system.
What is ground wave communication? On what factors does the maximum range of propagation in this mode depend?
Answer the following question.
In the skywave mode of propagation, why is the frequency range of transmitting signals restricted to less than 30 MHz?
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?
Light from a sodium lamp (S) passes through two polaroid sheets P1 and P2 as shown in fig. What will be the effect on the intensity of the light transmitted (i) by P1 and (ii) by P2 on the rotating polaroid P1 about the direction of propagation of light? Justify your answer in both cases.
The frequency range of 3 MHz to 30 MHz is used for ____________.
What do you mean by skip distance?
The length of half wave dipole at 30MH2 is
Polarization in e.m wave is caused by
In He-Ne loser the most favourable ratio of Helium toNe on for satisfactory laser action is
The characteristic impedance of a coaxial cable is of the order of
The component of the ground wave attenuated by conducting earth is ______.
Three waves A, B and C of frequencies 1600 kHz, 5 MHz and 60 MHz, respectively are to be transmitted from one place to another. Which of the following is the most appropriate mode of communication ______.
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?
The maximum frequency for reflection of sky waves from a certain layer of the ionosphere is found to be fmax = 9(Nmax)1/2, where Nmax is the maximum electron density at that layer of the ionosphere. On a certain day, it is observed that signals of frequencies higher than 5 MHz are not received by reflection from the F1 layer of the ionosphere while signals of frequencies higher than 8 MHz are not received by reflection from the F2 layer of the ionosphere. Estimate the maximum electron densities of the F1 and F2 layers on that day.
