Description : What value does a meter movement react to (actually measure) when measuring ac?
Last Answer : Average value.
Description : What is the purpose of a rectifier in a meter?
Last Answer : A rectifier changes alternating current to pulsating direct current and allows a dc meter to measure ac.
Description : What electrical property is used by all the meter movements discussed so far?
Last Answer : Current.
Description : The device which converts AC to DC is (1) Oscillator (2) Amplifier (3) Rectifier (4) None of these
Last Answer : (3) Rectifier Explanation: A rectifier is an electrical device that converts alternating current (AC). which periodically reverses direction, to direct current (DC), which flows in only one ... serving as components of DC power supplies and high-voltage direct current power transmission systems.
Description : A silicon controlled rectifier (SCR) is a solid state device used to change ________________. A. DC to AC and control relatively low load current B. AC to DC and control relatively high load ... to AC and control relatively high load current D. AC to DC and control relatively low load current
Last Answer : Answer: B
Description : The most common source of excitation for synchronous motors is a/an ______________. A. stepup transformer B. half-wave rectifier C. DC supply D. AC supply
Last Answer : Answer: C
Description : The output from a full wave rectifier is (a) A pulsating uni-directional current (b) A DC voltage (c) Zero (d) An AC voltage
Last Answer : a) A pulsating uni-directional current
Description : In a half wave rectifier the rms value of AC component of the waves (a) Zero (b) Equal to DC value (c) More than DC value (d) Less than DC value
Last Answer : b) Equal to DC value
Last Answer : Rectifier
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 : Which rectifier can convert AC to DC? A. Half wave rectifier B. Full wave rectifier C. Bridge wave rectifier D. All of these
Last Answer : Which rectifier can convert AC to DC? A. Half wave rectifier B. Full wave rectifier C. Bridge wave rectifier D. All of these
Last Answer : NO IT ONLY CONVERT FROM AC TO DC BECAUSE DIODE WHICH ARE USED IN IT, ARE UNIDIRECTIONAL.
Last Answer : IT CHANGES NEGATIVE CYCLE IN TO POSITIVE CYCLE FROM AC CURRENT.
Description : What are three advantages of adding an ac bias voltage to the input signal instead of adding a fixed dc bias voltage?
Last Answer : a. Reproduces a stronger output signal. b. Greatly improves the SNR. c. Greatly reduces the natural tape hiss.
Description : Besides setting up the meter for expected voltage ranges, what must be strictly observed when taking dc voltage readings?
Last Answer : Polarit
Description : How can a d’Arsonval meter movement be adapted for use as an ac meter?
Last Answer : By the use of a rectifier
Description : What value is indicated on the scale of an ac meter?
Last Answer : Effective value (rms).
Description : When troubleshooting electronic equipment, you should use a high impedance multimeter ________________. A. to prevent excess current flow through the meter that would damage it B. for AC measurements only ... being tested D. so as not to load down the circuit and obtain erroneous voltage readings
Last Answer : Answer: D
Description : An internal resistance is placed in series with the meter movement of which of the following instruments? A. AC ammeter B. DC ammeter C. DC voltmeter D. Frequency meter
Description : What is the basic difference between the primaries of ac and dc rate generators?
Last Answer : The method of primary excitation (ac and permanent magnet).
Description : Why does using ac vice dc bias voltage result in a stronger output signal?
Last Answer : Because an ac bias voltage of the proper frequency and level places the input signal away from both steps in the magnetism curve. The result is two undistorted output signals that are combined into one strong output.
Description : Why does adding dc vice ac bias voltage to the input signal result in a poor signal-to-noise ratio (SNR)?
Last Answer : With dc bias, the SNR is poor because only a small portion of the magnetism curve is straight enough to use, thus the output signal is weak compared with the natural tape hiss.
Description : What component causes a generator to produce dc voltage rather than ac voltage at its output terminals?
Last Answer : A commutator
Description : Why is the dc scale on a multimeter different than the ac scale?
Last Answer : The meter movement reacts to average ac voltage and current and the effective value is desired.
Description : How is it possible to use a current sensitive meter movement to measure voltage?
Last Answer : Since the resistance of a meter movement remains the same as the pointer is deflected, the amount of current through the movement is proportional to the voltage applied. Therefore, only the scale of the movement must be changed.
Description : What modification is made to the D’Arsonval meter movement to enable the meter to measure voltage?
Last Answer : A multimeter (high resistance) is placed in series with the coil of the meter.
Description : The purpose of the bias winding in figure 'B' shown in the illustration is for ____________. EL-0091 A. changing the direction of current in the control winding B. setting the operating point of the ... use of either AC or DC in the load circuit D. changing the direction of current through the load
Description : If reading AC current with the illustrated device and unsure of the range as a precaution , the first step should be to _________. EL-0047 A. secure power and test for voltage B. disconnect the ... resistance and use Ohm's law to calculate current D. unable to safely measure current with the device
Last Answer : Answer: A
Description : In a three phase controlled bridge rectifier with an increase of overlap angles the output dc voltage
Last Answer : In a three phase controlled bridge rectifier with an increase of overlap angles the output dc voltage decreases
Description : Thermocouple is used to measure a) AC b) DC c) Both d) None
Last Answer : Ans: Both
Description : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be (1) unaffected (2) decreased (3) increased (4) either decreased or increased depending on the direction of the DC field
Last Answer : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be either decreased or increased depending on the direction of the DC field
Description : What is the purpose of the rectifier in a magnetic amplifier?
Last Answer : The rectifier eliminates hysteresis loss.
Description : If a half-wave rectifier is added to a half-wave voltage doubler, the resulting circuit is a voltage ___
Last Answer : Trippler.
Description : Is a full-wave rectifier output easier to filter than that of a half-wave rectifier?
Last Answer : Yes.
Description : What main advantage does a bridge rectifier have over a conventional full-wave rectifier?
Last Answer : The bridge rectifier can produce twice the voltage with the same size transformer.
Description : What is the main disadvantage of a conventional full-wave rectifier?
Last Answer : Peak voltage is half that of the half-wave rectifier.
Description : What is the average voltage (Eavg) Output of a full-wave rectifier with an output of 100 volts peak?
Last Answer : 63.7 volts.
Description : What is the ripple frequency of a full-wave rectifier with an input frequency of 60 Hz?
Last Answer : 120 hertz.
Description : What was the major factor that led to the development of the full-wave rectifier?
Last Answer : The fact that the full-wave rectifier uses the full output, both half cycles, of the transformer.
Description : If the output of a half-wave rectifier is 50-volts peak, what is the average voltage
Last Answer : 15.9 volts.
Description : What is the name of the simplest type of rectifier which uses one diode?
Last Answer : The half-wave rectifier.
Description : What is the purpose of the rectifier section?
Last Answer : To change ac to pulsating dc.
Description : What type of rectifier is constructed by sandwiching a section of semiconductor material between two metal plates?
Last Answer : Metallic rectifier.
Description : What is the output of a half-wave rectifier?
Last Answer : A pulsating dc voltage.
Last Answer : The bridge rectifier can produce double the voltage with the same size transformer.
Description : What is the main disadvantage of the conventional full wave rectifier?
Last Answer : The peak voltage is half that of a half-wave rectifier.
Description : What is the average voltage (Eavg) output of a full-wave rectifier that has an output of 100 volts peak?
Last Answer : 63.6 volts.
Description : What is the equation for determining average voltage in a half-wave rectifier?
Last Answer : Eavg = 0.318 × Emax