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Answer :

Output transformer is always a Stepdown transformer

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Last Answer : The output stage of a practical amplifier is always Transformer coupled

Description :  An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V 

Last Answer :  An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V 

Description : In a full wave rectifier circuit using centre tapped transformer, the peak voltage across half of the secondary winding is 30 V. Then PIV is: (1) 30 V (2) 60 V (3) 15 V (4) 10 V

Last Answer : In a full wave rectifier circuit using centre tapped transformer, the peak voltage across half of the secondary winding is 30 V. Then PIV is: 60 V

Description : The transformer connection which has gained considerable popularity to serve 3-phase equipment and single phase lighting load is • Star/Star • Delta/Delta • Delta/Star • Star/Delta

Last Answer : The transformer connection which has gained considerable popularity to serve 3-phase equipment and single phase lighting load is Delta/Star

Description : In an oil filled transformer, oil is provided for (A) cooling (B) insulation (C) lubrication (D) both (A) and (B)

Last Answer : In an oil filled transformer, oil is provided for (A) cooling (B) insulation (C) lubrication (D) both (A) and (B)

Description : Transformer coupling introduces which type of distortion?

Last Answer : Transformer coupling introduces Cross over distortion.

Description : Define: i) Input Offset Voltage ii) Input offset Current iii) Input Bias Current iv) Output offset voltage

Last Answer : Definition of parameters of OPAMP is follows:  i) Input Offset Voltage: Input offset voltage is defined as the voltage that must be applied between the two input terminals of an OPAMP to null or ... to ground) and output voltage is obtained non zero such voltage is output offset voltage of opamp.

Description : For an earth station transmitter, with an antenna output power of 40dBW 10,000W, a back-off loss of 3dB, a total branching and feeder loss of 3dB, a total branching and feeder loss of 3dB and transmit ... effective isotropic radiated power (EIRP will be  a) 38dBW b) 40 dBW c 36 dBW d) 47 dBW

Last Answer : For an earth station transmitter, with an antenna output power of 40dBW 10,000W, a back-off loss of 3dB, a total branching and feeder loss of 3dB, a total branching and feeder loss of 3dB and transmit antenna gain of 4dB, the effective isotropic radiated power (EIRP will be 38dBW

Description : The threshold effect in demodulators is a) The rapid fall of output SNR when the input SNR falls below a particular value b) Exhibited by all the demodulators when the input SNR is low c) Exhibited by all AM suppressed carrier coherent demodulators d) Exhibited by correlation receivers

Last Answer : The threshold effect in demodulators is The rapid fall of output SNR when the input SNR falls below a particular value

Description : In a full wave rectifier with input frequency of 50 Hz, the frequency of the output is: (1) 50 Hz (2) 100 Hz (3) 150 Hz (4) 200 Hz

Last Answer : In a full wave rectifier with input frequency of 50 Hz, the frequency of the output is: 100 Hz

Description : The output waveform of a 555 Timer is: (1) Sinusoidal (2) Triangular (3) Rectangular (4) Elliptical 

Last Answer : The output waveform of a 555 Timer is: Rectangular

Description : Ripple in output current of a step-down chopper feeding RLE load is maximum, when duty cycle is equal to:  (1) 1 (2) 0.5 (3) 0.75 (4) 0.33

Last Answer : Ripple in output current of step down Chopper feeding a RLE load is maximum, when duty cycle is equal to 0.5

Description : The ripple voltage in the output of a single phase half wave rectifier with 10 V rectified dc voltage with resistive load and without filter will be • 12.1 volt • 1.21 volt • 0.482 volt • 4.82 volt

Last Answer : The ripple voltage in the output of a single phase half wave rectifier with 10 V rectified dc voltage with resistive load and without filter will be 12.1 volt

Description : The frequency stability of the oscillator output is maximum in _____.   (a) Crystal oscillator (b) Phase shift oscillator (c) LC oscillator (d) Wien bridge oscillator 

Last Answer : The frequency stability of the oscillator output is maximum in Crystal oscillator. 

Description : In a half-wave rectifier, if an a.c supply is 60 Hz. Then what is the a.c ripple at output? (A) 30 Hz (B) 60 Hz (C) 20 Hz (D) 15 Hz

Last Answer : In a half-wave rectifier, if an a.c supply is 60 Hz. Then what is the a.c ripple at output? (A) 30 Hz (B) 60 Hz (C) 20 Hz (D) 15 Hz

Description : In computer system Scanner is _________device. A. Input B. Output C. Both D. None 

Last Answer : In computer system Scanner is Input device. 

Description : A 4-bit R/2R digital-to-analog (DAC) converter has a reference of 5 volts. What is the analog output for the input code 1010:  (1) 0.3125 V (2) 3.125 V (3) 0.78125 V (4) –3.125 V

Last Answer : 3.125V

Description : The input to a coherent detector is DSB-SC signal plus noise. The noise at the detector output is:  (1) The in-phase component (2) The quadrature-component (3) Zero (4) The envelope

Last Answer : The input to a coherent detector is DSB-SC signal plus noise. The noise at the detector output is: Zero.

Description : An eight bit digital data 10101100 is fed to an ADC. The reference voltage is +10V. The analog output voltage will be:  (1) 1.05V (2) 6.74V (3) 10.10V (4) 5.15V

Last Answer : An eight bit digital data 10101100 is fed to an ADC. The reference voltage is +10V. The analog output voltage will be: 6.74V.

Description : In a strain measuring device, using a strain gauge, the output quantity is  A) Voltage B) resistance C) Impedance D) either A) or B)

Last Answer : In a strain measuring device, using a strain gauge, the output quantity is Voltage

Last Answer :  If firing angle in SCR increases, output is Decreases

Last Answer :  A Gate is a logic circuit with one or more inputs, but only One output

Last Answer : The OR gate has one or more high inputs, produces high output

Last Answer :  In a NOR gate all inputs must be Low to get high output

Last Answer : Among the three configuration, the highest output impedance is obtained by CB.

Description : What is the output current of a 480 Volt primary 208 volt secondary - 3 phase transformer?

Last Answer : You need to mention the Load connected to find the current.

Description : When a low input voltage is imparted to a device which then delivers a high output voltage, the device is known as a _____________. A. primary transformer B. secondary transformer C. stepdown transformer D. stepup transformer

Last Answer : Answer: D

Description : In the illustrated circuit, if the input to leads 'B' and 'Y' was 24 VDC the output between 'A' and 'X' will be _________. EL-0069 A. 24 VDC B. 22.8 VDC, 24 VDC minus the 1.2 VDC voltage drop across two diodes C. undeterminable without knowing the turns ratio of the transformer D. 0 VDC

Last Answer : Answer: D

Description : The voltage at the reference electrode of the circuit shown in the illustration is applied to the input of a/an ______________. EL-0090 A. class A detector whose output drives an ... drives an 2-stage isolation transformer D. magnetic amplifier whose output controls a saturable reactor

Last Answer : Answer: D

Description : If output voltage is greater than input voltage, then transformer is A. step up B. step down C. faulty D. fatal

Last Answer :  step up

Description : What is the speciality of the inverter output transformer? Why it is provided? 

Last Answer : a) This eliminates all 3rd harmonics in the output voltage. b) Solid earthed neutral is required for the inverter output, hence the interconnected star winding is essential. c) ... will cause circulating current between inverters during unbalanced faults. The inverters cannot withstand this. 

Description : In step down transformer, the AC output gives the current _________ than the input current.

Last Answer : more

Description : 48.During light loads, the transformer efficiency is low because A. Secondary output is low B. Transformer losses are high C. Fixed loss is high in proportion to the output D. Cu loss is small

Last Answer : C. Fixed loss is high in proportion to the output

Description : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Last Answer : (C) 3.0 V.

Description : If a transformer primary is energised from a square wave voltage source, its output voltage will be (A) A square wave. (B) A sine wave. (C) A triangular wave. (D) A pulse wave.

Last Answer : (A) A square wave.

Description : An AC supply of 230 V is applied to half wave rectifier circuit. A transformer turns ratio is 20 : 1. Find i) Output DC voltage (ii) Peak Inverse Voltage (PIV)

Last Answer : Solution:

Description : A single phase transformer is designed to operate from 50 Hz, 1100 V supply and to have an output voltage of 240 V at no load. The core has mean area of 30 cm2 and the flux density has not to exceed 1.3T. The number of secondary turns will be (a) 1270 (b) 1017 (c) 768 (d) 277  

Last Answer : E2=e2=4.44*flux*N2*f=240 V Flux=Flux density* Area Area=30 cm2  =30*10-4 m2 Flux= 1.3*30*10-4  Wb=39*10-4 Wb E=240= 4.44*39*10-4 *N2*50      N2=277.

Description : The main function of the transformer used in the output of a power amplifier is  (A) To step up the voltage  (B) to increase the voltage gain  (C) to safeguard the transistor against overheating  (D) to match the load impedance with dynamic output resistance of the transistor

Last Answer : The main function of the transformer used in the output of a power amplifier is to match the load impedance with dynamic output resistance of the transistor

Description : If a transformer primary is energised from a square wave voltage source, its output voltage will be a:  (A) square wave (B) sine wave (C) triangular wave (D) pulse wave

Last Answer : D

Description : On AC vessels, which of the following statements represents the most difficult problem involved in obtaining a DC potential suitable for use by computer components? A. A stepdown transformer is ... voltage must be rectified and made ripple free. D. Rectifiers cannot operate with voltage regulators.

Last Answer : Answer: C

Description : Why the tap changers are always connected to HV side of the transformer? 

Last Answer : During tap changing action the load current has to be shifted from one tap to another tap. In case HV wining the load current will be less. Hence lesser arcing will take place. 

Description : An ideal transformer always obeys the law of conservation of........: a. energy b. momentum c. charge d. Flux

Last Answer : b. momentum

Description : 28.In a two winding transformer, the emf /turn in secondary winding is always......the induced emf power turn in primary A. equal to k times B. equal to 1/k times C. equal D. greater than

Last Answer : C. equal

Description : 6 In a two winding transformer, the primary and secondary induced emf E1 & E2 are always A. equal in magnitude B. anti phase with each other C. in phase with each other D. determined by load on transformer secondary

Last Answer : C. In phase with each other

Description : State why a transformer always have an efficiency of more than 90%.

Last Answer : As transformer is static device with no moving parts, the losses due to friction & windage are completely absent. Hence transformer has efficiency of more than 90%.

Description : The secondary of a current transformer is always short-circuited under operating conditions because it?

Last Answer : The secondary of a current transformer is always short-circuited under operating conditions because it avoids core saturation and high voltage induction.