Assertion: Diode lasers are used as optical sources in optical communication.
Reason: Diode lasers consume less energy.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
Assertion: Television signals are received through sky-wave propagation.
Reason: The ionosphere reflects electromagnetic waves of frequencies greater than a certain critical frequency.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
Assertion: In high latitude one sees colorful curtains of light hanging down from high altitudes.
Reason: The high energy charged particles from the sun are deflected to polar regions by the magnetic field of the earth.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
Assertion: Short wave bands are used for transmission of radio waves to a large distance.
Reason: Short waves are reflected by ionosphere.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
Assertion: The electrical conductivity of earth's atmosphere decreases with altitude.
Reason: The high energy particles (i.e. (-rays and cosmic rays) coming from outer space and entering our earth's atmosphere cause ionization of the atoms of the gases present there and the pressure of gases decreases with increase in altitude.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If assertion is false but reason is true
Assertion: The electromagnetic waves of shorter wavelength can travel longer distances on earth's surface than those of longer wavelengths.
Reason: Shorter the wavelength, the larger is the velocity of wave propagation.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
Assertion: The surface wave propagation is used for medium wave band and for television broadcasting.
Reason: The surface waves travel directly from transmitting antenna to receiver antenna through atmosphere.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
Assertion: The television broadcasting becomes weaker with increasing distance.
Reason: The power transmitted from TV transmitter varies inversely as the distance of the receiver.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
Assertion: Microwave propagation is better than the sky wave propagation.
Reason: Microwaves have frequencies 100 to 300 GHz, which have very good directional properties.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
Assertion: Satellite is an ideal platform for remote sensing.
Reason: Satellite in polar orbit can provide global coverage or continuous coverage of the fixed area in geostationary configuration.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
Assertion : Fax is a modulating and demodulating device.
Reason : It is necessary for exact reproduction of a document.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If assertion is false but reason is true
Assertion: A dish antenna is highly directional.
Reason : This is because a dipole antenna is omni directional.
If both assertion and reason are true and the reason is the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true but reason is false.
If the assertion and reason both are false
In short wave communication waves of which of the following frequencies is reflected back by the ionosphere layer, having electron density 1011 per m3 ____.
2 MHz
10 MHz
12 MHz
18 MHz
In an amplitude modulated wave for audio frequency of 500 cycle / second, the appropriate carrier frequency is ____.
50 cycles / s
100 cycles / s
500 cycles / s
50,000 cycles / s
AM is used for broadcasting because ____.
it is more noise immune than other modulation systems
it requires less transmitting power compared with other systems
its use avoids receiver complexity
no other modulation system can provide the necessary bandwidth faithful transmission
Range of frequencies allotted for commercial FM radio broadcast is ____.
88 to 108 MHz
88 to 108 kHz
8 to 88 MHz
88 to 108 GHz
The velocity factor of a transmission line x. If dielectric constant of the medium is 2.6, the value of x is ____.
0.26
0.62
2.6
6.2
The process of superimposing signal frequency (i.e. audio wave) on the carrier wave is known as ____.
transmission
reception
modulation
detection
Long distance short-wave radio broadcasting uses ____.
ground wave
ionosphere wave
direct wave
sky wave
A step index fiber has a relative refractive index of 0.88%. What is the critical angle at the core cladding interface?
60°
75°
45°
None of the above
The characteristic impedance of a coaxial cable is of the order of ____.
50 (
200 (
270 (
None of the above