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Question #21Basic Electricity and Electronics

A capacitor and inductor in series is called a

  1. Tuned Circuit ✓ Correct answer
  2. Timing Circuit
  3. Delay Circuit
  4. Schmitt Circuit
Explanation: A capacitor and inductor form a tuned (resonant) circuit.

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Question #22Radio Theory and Communication Principles

A domestic inverter

  1. Converts ac to ac
  2. Converts ac to dc
  3. Converts dc to ac ✓ Correct answer
  4. Converts dc to dc
Explanation: A domestic inverter converts DC from a battery into AC.

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Question #23Basic Electricity and Electronics

The current in a circuit is 25mA, then the equivalent value is

  1. 0.00025 Ampere
  2. 0.0025 Ampere
  3. 0.025 Ampere ✓ Correct answer
  4. 0.25 Ampere
Explanation: 25 mA = 0.025 A.

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Question #24Basic Electricity and Electronics

If 2 mA current flows through a 100 Kohm resistor, then the voltage across it is

  1. 2 volts
  2. 20 volts
  3. 200 volts ✓ Correct answer
  4. 0.2 volts
Explanation: V = IR = 0.002 A × 100,000 Ω = 200 V.

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Question #25Radio Theory and Communication Principles

The tolerance bands with colors gold, silver & brown represent

  1. 5%, 10%, 2%
  2. 5%, 10%, 1% ✓ Correct answer
  3. 10%, 5%, 1%
  4. 10%, 5%, 2%
Explanation: Gold, silver and brown tolerance bands represent 5%, 10% and 1%, respectively.

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Question #26Radio Theory and Communication Principles

India uses which encoding technique for commercial TV broad cast

  1. NTSC
  2. SECAM
  3. PAL ✓ Correct answer
  4. None of the above
Explanation: India’s analogue terrestrial television system used PAL.

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Question #27Radio Theory and Communication Principles

The video bandwidth in a TV transmission in India is

  1. 455 KHz
  2. 10.7 MHz
  3. 4.2 MHz ✓ Correct answer
  4. 5.5 MHz
Explanation: The conventional Indian PAL-B/G television system used approximately 5.5 MHz sound spacing and 5 MHz channel characteristics; the stated video bandwidth answer in this legacy question is 4.2 MHz.

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Question #28Antennas and Radio Wave Propagation

Sky wave propagation utilizes

  1. Troposphere
  2. Stratosphere
  3. Ionosphere ✓ Correct answer
  4. Exosphere
Explanation: Sky-wave propagation relies on refraction/return of radio waves by the ionosphere.

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Question #29Antennas and Radio Wave Propagation

Ionosphere does not have _______ layer.

  1. C ✓ Correct answer
  2. D
  3. E
  4. F
Explanation: The recognised ionospheric regions are D, E, F1 and F2; there is no C layer.

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Question #30Antennas and Radio Wave Propagation

Which layer of ionosphere disappears during night time?

  1. C
  2. D ✓ Correct answer
  3. E
  4. F
Explanation: The D layer largely disappears at night because solar ionisation falls.

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Question #31Antennas and Radio Wave Propagation

In dealing with sky/ground wave propagation, the area of silence where no signals are received is the

  1. dead zone
  2. skip distance
  3. skip zone ✓ Correct answer
  4. propagation distance.
Explanation: The skip zone is the region between the end of ground-wave coverage and the first returned sky wave.

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Question #32Antennas and Radio Wave Propagation

Frequencies lesser than the critical frequency are

  1. passed into space
  2. the most desirable
  3. returned to earth ✓ Correct answer
  4. refracted by the F2 layer
Explanation: Below the critical frequency, a wave can be refracted back toward Earth under suitable ionospheric conditions.

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Question #33Radio Theory and Communication Principles

For mobile communications, the up-link frequency is _____ down link frequency .

  1. Less than
  2. More than ✓ Correct answer
  3. Equal to
  4. Less or more than the
Explanation: In typical cellular systems, the mobile uplink frequency is higher than the downlink frequency.

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Question #34Radio Theory and Communication Principles

All India Radio (AIR) does not broadcast

  1. Amplitude Modulation transmission
  2. Frequency Modulation transmission
  3. Pulse Modulation transmission ✓ Correct answer
  4. Both a and b
Explanation: Pulse modulation is not a normal broadcast mode used by All India Radio.

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Question #35Basic Electricity and Electronics

A diode can be used in the following stages of a radio receiver

  1. Detector
  2. Mixer
  3. Rectification
  4. All of the above ✓ Correct answer
Explanation: Diodes are used in detector, mixer and rectifier circuits.

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Question #36Radio Theory and Communication Principles

Geo stationary orbit is ___ km away from the earth

  1. 3100
  2. 35,786 km ✓ Correct answer
  3. 36786
  4. 39000
Explanation: A geostationary orbit is approximately 35,786 km above the Earth’s equator.

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Question #37Antennas and Radio Wave Propagation

Which antenna is used for direction finding purpose?

  1. Loop antenna ✓ Correct answer
  2. Active Whip antenna
  3. Whip antenna
  4. Dipole antenna
Explanation: A loop antenna has a directional null and is commonly used for radio direction finding.

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Question #38Basic Electricity and Electronics

A transformer converts

  1. AC voltage into DC voltage
  2. DC voltage into AC voltage
  3. AC voltage into different AC voltage ✓ Correct answer
  4. DC voltage into different DC voltage
Explanation: A transformer changes one AC voltage level to another AC voltage level.

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Question #39Basic Electricity and Electronics

A matching transformer (10:1 turns ratio) is used to match 200 ohms into ___ ohms.

  1. 2 ✓ Correct answer
  2. 20
  3. 200
  4. 5
Explanation: A 10:1 turns ratio gives a 100:1 impedance ratio; 200 Ω / 100 = 2 Ω.

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Question #40Basic Electricity and Electronics

The following are transformer losses

  1. Hysteresis losses
  2. Eddy current losses
  3. Copper losses
  4. All of the above ✓ Correct answer
Explanation: Transformer losses include copper, hysteresis and eddy-current losses.

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