Which of the following modulation techniques is mostly used in inverters ?
The gain of a parabolic dish antenna of 1 m diameter -and 80% efficiency at 9.5 GHz is:
asked Apr 12, 2018 in Electronics Engineering by Shimroz123
The gain of a parabolic dish antenna of 1 m diameter -and 80% efficiency at 9.5 GHz is: a. 39 dB b. 78 dB c. 40 dB d. 45 dB
A commutator with a diameter of 50 cm rotates at 1000 r.p.m. If brush width is 1.5 cm, the time of
A commutator with a diameter of 50 cm rotates at 1000 r.p.m. If brush width is 1.5 cm, the time of commutation will be (a) 0.168 m sec (b) 0.374 m sec (c) 0.481 m sec (d) 0.573 m sec
To increase gain of a parabolic reflector antenna by 6dBi, the correct statement is :
To increase gain of a parabolic reflector antenna by 6dBi, the correct statement is : ( Assuming efficiency 70%) a. Diameter is to be increased to 6 folds b. Diameter is to be increased to 4 folds c. Diameter is to be increased to 2 folds d. None of above
When a dipole antenna of 1/8 length has an equivalent total resistance of 1.5 Watt then the efficiency of the
When a dipole antenna of 1/8 length has an equivalent total resistance of 1.5 Watt then the efficiency of the antenna is (A) 0.89159% (B) 8.9159% (C) 89.159% (D) 891.59%
asked May 17, 2018 in Electronics communication by Shimroz123
A Doppler Radar operating at 15 GHz is viewing a target moving directly towards it at the speed of 25 m/s.
A Doppler Radar operating at 15 GHz is viewing a target moving directly towards it at the speed of 25 m/s. The Doppler frequency shift
If the antenna diameter in a radar system is increased by a factor of 4, the maximum range will be increased ...
If the antenna diameter in a radar system is increased by a factor of 4, the maximum range will be increased by a factor of (a) 2 (b) 4 (c) 8 (d) 16
asked Apr 9, 2018 in Electronics Engineering by Shimroz123
The magnetic field intensity at the centre of a current carrying coil of diameter J m is K. The current flowing
The magnetic field intensity at the centre of a current carrying coil of diameter J m is K. The current flowing in the coil is
A 4 GHz carrier is amplitude modulated by a low-pass signal of maximum cut off frequency 1 MHz
A 4 GHz carrier is amplitude modulated by a low-pass signal of maximum cut off frequency 1 MHz. lf this signal is to be ideally sampled, the minimum sampling frequency should be nearly
A two conductor 1 - pi line operates at 50 Hz. The diameter of each conductor is 20 mm...
A two conductor 1 - pi line operates at 50 Hz.The diameter of each conductor is 20 mm and the spacing between the conductors is 3m, The height of conductor above the ground is 6 m. The capacitance of the line to neutral will be?
asked Mar 27, 2018 in Power system by Shimroz123
A two conductor 1 - pi line operates at 50 Hz. The diameter of each conductor is 4 cm...
A two conductor 1 - pi line operates at 50 Hz.The diameter of each conductor is 4 cm and are spaced 6 m apart. What is the capacitive susceptance to neutral per km?
A two conductor 1 - pi line operates at 50 Hz. The diameter of each conductor is 2 cm and are spaced 3m apart. What is the line to line capacitance ?
Total numbers of ascending runs in the sequence 4 6 7 2 9 1 2 8 9 3 0 (1) 3 (2) 5 (3) 7 (4) 9
A dc shunt motor runs at 500 r.p.m at 220 V. A resistance of 4.5 Ω is added in series with the armature for...
A dc shunt motor runs at 500 r.p.m at 220 V. A resistance of 4.5 Ω is added in series with the armature for speed control. The armature resistance is 0.5 ohms. The current to stall the motor will be (1) 44 A (2) 50 A (3) 44.4 A (4) 60 A
The sending end and receiving end voltages of a three-phase transmission line are 10 kV/ph and 9.5 kV/ph,
The sending end and receiving end voltages of a three-phase transmission line are 10 kV/ph and 9.5 kV/ph, respectively. If the resistance drop is 150 V/ph and receiving end power factor is 0.8, the sending end power factor is (A) 0.745 lagging (B) 0.775 lagging (C) 0.8 lagging (D) 0.85 lagging
voltages
three-phase
A synchronous motor is delivering 80% of its rated output and is operating at UPF. If its excitation is increased...
A synchronous motor is delivering 80% of its rated output and is operating at UPF. If its excitation is increased, then (1) the output delivered gets increased (2) its pf becomes lagging (3) the output delivered gets decreased (4) its pf becomes leading
Earth coverage dish antenna is used in satellite system. It is characterized by the fact that
Earth coverage dish antenna is used in satellite system. It is characterized by the fact that (a) It is a narrow beam antenna (b) It is Parabolic antenna (c) it is sharply focused within a small area of the surface of the earth (d) it is a wide angle antenna which covers a large area of the surface of the earth
The RF amplifier A is having 3 dB NF & 5 dB of gain, amplifier B is having 3.5 dB NF & 15 dB . For overall noise...
The RF amplifier A is having 3 dB NF & 5 dB of gain, amplifier B is having 3.5 dB NF & 15 dB . For overall noise figure of the cascaded system, the correct statement is : a. A as first stage & B as second stage offers minimum over all NF b. B as first stage & A as second stage minimum over all NF c. Both the combination will offer same overall NF d. Over all NF will be less than 3 dB.
A two conductor 1 - pi line operates at 50 Hz. The diameter of each ...
A two conductor 1 - pi line operates at 50 Hz. The diameter of each conductor is 20 mm and the spacing between conductors is 3m. What is the inductance of each conductor per km?
The Q factor of a coil at resonant frequency 1.5 MHz of an RLC series circuit is 150. The Bandwidth is : -
The Q factor of a coil at resonant frequency 1.5 MHz of an RLC series circuit is 150. The Bandwidth is : - a) 225 MHz b) 1.06 MHz c) 10 KHz d) 10 MHz
The directive gain of an antenna:
The directive gain of an antenna: (1) is less than or equal to 1 (2) is greater than or equal to 1 (3) lies between 0 and directivity of antenna (4) is greater than directivity of antenna
asked May 29, 2018 in Electronics Engineering by Shimroz123
What is the energy stored in the magnetic field at a solenoid of 40 cm long and 4 cm diameter wound with...
What is the energy stored in the magnetic field at a solenoid of 40 cm long and 4 cm diameter wound with 100 turns of wire carrying a current at 20A? (A) 0.705 Joule (B) 0.789 Joule (C) 0.587 Joule (D) 0.658 Joule
For an existing ac transmission line, the string efficiency is 80%, if dc...
For an existing ac transmission line, the string efficiency is 80%, if dc voltage is supplied for the same setup, the string efficiency will be?
What is the resistance of a 160 m wire with a uniform diameter of 0.28 mm, if the specific resistance is
What is the resistance of a 160 m wire with a uniform diameter of 0.28 mm, if the specific resistance is 12.32 μΩ-cm? A) 3.2 Ω B) 3.2 μΩ C) 0.8 Ω D) None of these
In a differential amplifier the differential voltage gain is 500 and the common mode voltage gain is 0.5. ...
In a differential amplifier the differential voltage gain is 500 and the common mode voltage gain is 0.5. The CMRR in dB is (a) 80 (b) 60 (c) 30 (d) 20
A pulse radar has a pulse repetition frequency (PRF) of 3 KHz. If the radar is emitting at 10 GHz, what is the
A pulse radar has a pulse repetition frequency (PRF) of 3 KHz. If the radar is emitting at 10 GHz, what is the maximum unambiguous range for this radar? A) 5 Km B) 5 m C) 50 Km D) 15 m
asked Jun 18, 2018 in Electrical Engineering by Shimroz123
emitting
A 3 layer, total diameter of an ACSR conductor is 5 cm. Find the diameter of each strand?
asked May 8, 2018 in Electric Power Transmission by Shimroz123
acsr
A drawn wire of resistance 5 Q is further drawn so that its diameter becomes one-fifth of the original. ...
A drawn wire of resistance 5 Ω is further drawn so that its diameter becomes one-fifth of the original. What is its resistance with volume remaining the same ? (a) 25 Ω (b) 125 Ω (c) 625 Ω (d) 3125 Ω
If three wires of 3 ohms, 9 ohms and 5 ohms respectively are connected in series, what their
If three wires of 3 ohms, 9 ohms and 5 ohms respectively are connected in series, what their resultant resistance? A.10 ohms B.12 ohms C.17 ohms D.5 ohms
asked May 15, 2018 in Basic concepts by Shimroz123
The connected load of a consumer is 2 kW and his maximum demand is 1.5 kW. The load factor of the
The connected load of a consumer is 2 kW and his maximum demand is 1.5 kW. The load factor of the consumer is (a) 0.375 (b) 0.75 (c) 1.33 (d) None of these
asked May 26, 2018 in Electric Power Transmission by Shimroz123
System 1 : The first column of the RH array consists of the terms 6,3,9,-2, and 4. System 2 : The first column of
System 1 : The first column of the RH array consists of the terms 6,3,9,-2, and 4. System 2 : The first column of the RH array consists of the terms 3,6,9,2, and -4. The number of unstable poles for system1, and system 2, are respectively, (A) 1,1 (B) none, none (C) 2,2 (D) 2,1
asked Apr 28, 2018 in Control System by Shimroz123
A transformer has maximum efficiency at 3/4 full load. The ratio of its iron losses and full load copper loss is : -
A transformer has maximum efficiency at 3/4 full load. The ratio of its iron losses and full load copper loss is : - a) 16/9 b) 4 / 3 c) 3/4 d) 9 /16
If three stage amplifiers has individual stage gain of 10 db, 5 db & 12 db then the total gain
asked Mar 29, 2018 in Electronics Engineering by Shimroz123
The resolved part of the resultant of two forces inclined at an angle 9 in a given direction is equal to?
The resolved part of the resultant of two forces inclined at an angle 9 in a given direction is equal to
asked Mar 22, 2018 in Engineering Mechanics by Shimroz123
A differential amplifier has a differential gain of 28000 and CMRR is 60 dB. What will be the value of common
A differential amplifier has a differential gain of 28000 and CMRR is 60 dB. What will be the value of common mode gain? A) Ac = 0.125 B) Ac = 0.33 C) Ac = 3 D) Ac = 28
asked Jun 18, 2018 in Electronics Engineering by Shimroz123
cmrr
In any transmitting antenna system, efficiency primarily depends upon
A d.c. source has an open circuit voltage of 30 V and an internal resistance of 1.5 Ohm. A resistive load is ...
A d.c. source has an open circuit voltage of 30 V and an internal resistance of 1.5 Ohm. A resistive load is connected to the source. Maximum power dissipated in the load is (A) 300 W (B) 150 W (C) 45 W (D) 20 W
If the feedback factor of an amplifier is 0.1 and its gain without feedback is 40, then its gain with feedback is
If the feedback factor of an amplifier is 0.1 and its gain without feedback is 40, then its gain with feedback is (a) – 13.3 (b) 200 (c) 8 (d) 10
asked May 25, 2018 in Amplifier by Shimroz123
A material has conductivity of 10–2 mho/m and relative permittivity of 4. The frequency at which the
A material has conductivity of 10–2 mho/m and relative permittivity of 4. The frequency at which the conduction current in the medium is equal to the displacement current, is (a) 450 MHz (b) 900 MHz (c) 45 MHz (d) 90 MHz
asked May 25, 2018 in Physics by Shimroz123
A 1-phase, 7.46 kW motor is supplied from a 400 V, 50 Hz A.C mains. Its efficiency is 85% and power factor is ...
A 1-phase, 7.46 kW motor is supplied from a 400 V, 50 Hz A.C mains. Its efficiency is 85% and power factor is 0.8 lagging. Calculate the KVA input (1) 9.56 kVA (2) 5.4 Kva (3) 10.97 kVA (4) 8.6 kVA
An amplifier which has almost same gain and input resistance of a CE amplifier but of higher bandwidth is...
An amplifier which has almost same gain and input resistance of a CE amplifier but of higher bandwidth is A) Cascode amplifier B) Cascade amplifier C) Darligton amplfier D) CC amplifier
In a microwave test bench, why is the microwave signal amplitude modulated at 1 kHz?
In a microwave test bench, why is the microwave signal amplitude modulated at 1 kHz? (1) To increase the sensitivity of measurement (2) To transmit the signal to a far-off place (3) To study amplitude modulation (4) Because crystal detector fails at microwave frequencies
The line of sight communication requires transmit and receive antenna to face each other. If the transmit...
The line of sight communication requires transmit and receive antenna to face each other. If the transmit antenna is vertically polarized, for the best reception the receive antenna should be: (1) Horizontally polarized (2) Vertically polarized (3) At 45° with respect to the horizontal polarization (4) At 45° with respect to the vertical polarization
Consider the following statements with regard to a GTO : 1. The turn-off gain of the GTO is large....
Consider the following statements with regard to a GTO : 1. The turn-off gain of the GTO is large. 2. Large negative gate current pulses are required to turn off the GTO. 3. GTO has large reverse blocking capability. Which of the above statements is/are correct ? (a) 1 only (b) 2 only (c) 3 only (d) 1, 2 and 3
A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at
A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is (A) 86.7% (B) 88.26% (C) 88.9% (D) 87.8%
A 1:5 step-up transformer has 120V across the primary and 600 ohms resistance across the secondary....
A 1:5 step-up transformer has 120V across the primary and 600 ohms resistance across the secondary. Assuming 100% efficiency, the primary current will be: (A) 0.2 Amp. (B) 5 Amps. (C)10 Amps. (D) 20 Amps
How does the resistance of a circular conductor behave, if the diameter of the conductor is halved?
How does the resistance of a circular conductor behave, if the diameter of the conductor is halved? A) Remains unchanged B) Doubles C) Becomes 4 times D) Becomes one -fourth
An SSB transmitter produces a peak-to-peak voltage of 200 V across a 100 Ω antenna load. What is the Peak
An SSB transmitter produces a peak-to-peak voltage of 200 V across a 100 Ω antenna load. What is the Peak Envelope Power? A) 49.98 W B) 79.98 W C) 99.96 W D) 199.93 W
peak-to-peak
A carrier signal of 600 V rms with 75% amplitude modulation is applied to 75 ohm antenna. The total side...
A carrier signal of 600 V rms with 75% amplitude modulation is applied to 75 ohm antenna. The total side band power (in watts) is A) 4800 B) 450 C) 950 D) 1350