Type of communication possible by Modem duplex is …………………
1) Half duplex 2) Simplex 3) Doudle Duplex 4) Full duplex Answer: 4) Full duplex Solution: Type of communication possible by... View Article
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Which of the following is the disadvantage of FM over AM?
1) Larger bandwidth requirement 2) Larger noise 3) Higher modulation power 4) Low efficiency Answer: 1) Larger bandwidth requirement Solution: Frequency... View Article
Basically, the product modulator is
1) An amplifier 2) A mixer 3) A frequency separator 4) A phase separator Answer: 2) A mixer Solution: The product... View Article
Maximum usable frequency (MUF) in F-region layer is x, when the critical frequency is 60 MHz and the angleof incidence is 70°. Then x is
1) 150 MHz 2) 170 MHz 3) 175 MHz 4) 190 MHz Answer:3) 175 MHz Solution: From Snell’s law μ1sini=μ2sinr... View Article
The characteristics impedance of a coaxial cable of the order of
1) 50 Ω 2) 200 Ω 3) 27 Ω 4) None of these Answer: 1) 50 Ω Solution: The characteristics impedance... View Article
Suppose the sun was located at the position occupied by the nearest star, say, alphacenturi 4 light years away. By what factor the solar radiation received per sec per unit area decrease
1) 1.5 × 10–6 2) 1.5 × 10–8 3) 1.5 × 10–9 4) 1.5 ×10–11 Answer: 4) 1.5 ×10–11 Solution: \(\begin{array}{l}\frac{E_{2}}{E_{1}}=... View Article
Assertion Diode lasers are used as optical sources in optical communication.
Reason Diode lasers consume less energy.
1) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion. 2) If... View Article
Statement I Sky wave signals are used for long distance radio communication. These signals are in general, less stable than ground wave signals.
Statement II The state of ionosphere varies from hour to hour, day to day and season to season
1) Statement I is true, statement II is true; statement II is a correct explanation for statement I 2) Statement... View Article
An amplitude modulated wave is modulated to 50%. What is the saving in power if carrier as well as one of the side bands are suppressed?
1) 70% 2) 65.4% 3) 94.4% 4) 25.5% Answer:3) 94.4% Solution: Psb = Pc(ma/2)2 = Pc(0.5)2/4 = 0.0625 Pc Also... View Article
The maximum range, dmax, of radar is
1) Proportional to the cube root of the peak transmitted power 2) Proportional to the fourth root of the peak... View Article
A photodetector is made from a semiconductor with Eg = 0.73 eV. What is the maximum wavelength, which it can detect?
1) 1000 nm 2) 1703 nm 3) 500 nm 4) 173 nm Answer: 2) 1703 nm Solution: The energy of photon... View Article
Radar has a power of 1 kW and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500 m. The maximum distance up to which it can detect objects located on the surface of the earth (Radius of earth = 6.4 x 106m) is
1) 80 km 2) 16 km 3) 40 km 4) 64 km Answer: 1) 80 km Solution: Let d be the... View Article
Phase difference between space current and capacitive current is
1) π rad 2) π/2 rad 3) 3π/2 rad 4) μ rad Answer: 1) π rad Solution: The phase difference... View Article
What is the velocity of electromagnetic waves in a good conductor
1) 3 x 108 m/s 2) More than 3 x 108 m/s 3) High 4) Very low Answer: 4) Very low... View Article
How long will it take to transmit the information 30 km away in space?
1) 0.1 m s 2) 0.1 µ s 3) 0.1 n s 4) 0.1 p s Answer: 1) 0.1 m s... View Article
When electromagnetic waves enter the ionised layer of the ionosphere, the relative permitting of the ionised layer
1) Remain constant 2) Appears to decrease 3) Appears to increase 4) Changer randomly Answers: 2) Appears to decrease Solution: When... View Article
For 100% modulation, What is the value of minimum amplitude ( Emin ) of the modulated wave?
1) Zero 2) 1 3) 2 4) 3 Answer: 1) Zero Solution: m = [(Emax – Emin) / (Emax + Emin)]... View Article
A silicon optical fibre with a core diameter large enough has a care refractive index of 1.50 and a cladding refractive index of 1.47. The critical angle at the core-cladding interface is ___________
1) 87.50 2) 78.50 3) 38.50 4) 450 Answer: n1 = core refractive index = 1.5 n2 = cladding refractive... View Article
What type of medium is used in optical communication?
1) Guided medium 2) Unguided medium 3) Both guided and unguided media 4) Neither guided nor unguided media Answer: 1) Guided... View Article
What is the frequency range of signals that can be transmitted in the care of twisted pair of wires?
1) 5 MHz to 20 MHz 2) 5 MHz to 10 MHz 3) 100 Hz to 4 MHz 4) 5... View Article
