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286 views
0 answers
asked
Oct 14, 2020
by
anonymous
why ohm's law is not applicable for ac circuit?
Last Answer : We can use Ohm's law for AC circuit if circuit consists of linear components and devices.
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567 views
3 answers
asked
Oct 2, 2017
by
anonymous
A 35 V dc supply is connected across a resistance of 600 ohm in series with an unknown resistance R. A voltmeter having a resistance of 1.2 kOhm is connected across 600 ohm resistances and reads 5 V. The value of resistance R shall be:
Last Answer : A 35 V dc supply is connected across a resistance of 600 ohm in series with an unknown resistance R. A voltmeter having a resistance of 1.2 kOhm is connected across 600 ohm resistances and reads 5 V. The value of resistance R shall be: 2.4 kOhm
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178 views
1 answer
asked
May 22, 2018
by
anonymous
We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be
Last Answer : We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be 2.4 kOhm
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151 views
1 answer
asked
May 8, 2018
by
anonymous
A dc voltmeter has a sensitivity of 1000 Ohm/V. When it measures half full scale in 100 V range, the current through the voltmeter is
Last Answer : A dc voltmeter has a sensitivity of 1000 Ohm/V. When it measures half full scale in 100 V range, the current through the voltmeter is 1 mA.
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772 views
1 answer
asked
Apr 23, 2018
by
anonymous
A 220 V dc machine has an armature resistance o f 1-ohm. If the full load current is 20A, the difference in the induced voltage when the machine is running as a motor, and as a generator is
Last Answer : A 220 V dc machine has an armature resistance o f 1-ohm. If the full load current is 20A, the difference in the induced voltage when the machine is running as a motor, and as a generator is 40 V.
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535 views
1 answer
asked
Apr 1, 2018
by
anonymous
A Reactor having an inductive reactance of 4 ohm is connected to the terminals of a 120 V AC generator. Calculate the power associated with the reactor. (A) 3.6 kvar (B) 30 kvar (C) 7.2 kvar (D) 4.16 kvar
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139 views
0 answers
asked
Apr 5, 2018
by
anonymous
a dc generator has a terminal voltage of 250V and an induced voltage of 262V when the generator is loaded. the brush drop is 1volt per brush and the armature resistance is 0.03 ohm ... reaction and determine the following: the load current the power of the load the percentage voltage regulation.
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13 views
0 answers
asked
Aug 3, 2021
by
yanga
The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 ... .5 A from the same source will be (A) 48.0% (B) 57.1% (C) 59.2% (D) 88.8%
Last Answer : The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be 48.0%
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503 views
1 answer
asked
May 17, 2018
by
anonymous
A balanced Delta connected load supplied with 440 V 50 Hz three phase AC supply has R=10 Ohm and L=0.6 mH in is each arm. Calculate line and phase current, active power.
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255 views
0 answers
asked
Aug 12, 2018
by
anonymous
An R-L series AC circuit has R = 10 ohm and XL = 10 ohm. It is connected to an AC voltage source, the phase angle between voltage and current is (a) 30° (b) 45° (c) 60° (d) 36.8°
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153 views
0 answers
asked
May 25, 2018
by
anonymous
Kirchhoff's current law is applicable to 1. Closed loops in a circuit 2. Junction in a circuit 3. Magnetic circuits Which of the above is/are correct ? (a) 1 only (b) 2 only (c) 3 only (d) 1, 2 and 3
Last Answer : Kirchhoff's current law is applicable to 1. Closed loops in a circuit 2. Junction in a circuit 3. Magnetic circuits Which of the above is/are correct ? (a) 1 only (b) 2 only (c) 3 only (d) 1, 2 and 3
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310 views
1 answer
asked
Apr 25, 2018
by
anonymous
Ohm’s law is applicable to : (A) Semi-conductors (B) Vacuum tubes (C) Electrolytes (D) Semiconductors and Vacuum tubes
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131 views
0 answers
asked
Mar 31, 2018
by
anonymous
Last Answer : Ohm's law is not applicable to semi-conductors.
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78 views
1 answer
asked
Mar 31, 2018
by
anonymous
is Ohms law applicable to vacuum tubes?
Last Answer : Ohm's law is not applicable to vacuum tubes.
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244 views
1 answer
asked
Aug 16, 2017
by
anonymous
What is the advantage of AC over DC electrical transmission?
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82 views
0 answers
asked
Apr 26, 2020
by
anonymous
Last Answer : dc
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86 views
2 answers
asked
Mar 29, 2020
by
DHARAVATH Hussain Naik
Why are DC motors used in trains and not AC motors ?
Last Answer : The reason is torque. torque is inversely proportional to speed..i.e when th knowe train comes to rest position to motion.. initial speed is zero..so it requires high starting torque for ... current will flow through field and armature coils then maximum torque is available at the intial condition.
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164 views
1 answer
asked
Sep 3, 2019
by
anonymous
Why is AC considered more efficient than DC?
Last Answer : Ac is more efficient than dc because it is easy to maintain and change the voltage of ac for transmission and distribution purpose. Plant cost of ac transmission is much lower compared to dc transmission. When fault occurs it is easy to interrupt ac supply.
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100 views
1 answer
asked
Aug 28, 2019
by
anonymous
Which is more dangerous AC or DC and why ?
Last Answer : Dc is more dangerous than Ac because in Ac the voltage will varies but in dc the constant voltage
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152 views
2 answers
asked
Aug 28, 2019
by
anonymous
Why is AC better for long distance power transmission than DC ?
Last Answer : ac is more economical to transmit for long distances . wires can be made smaller by step up transformer .. since major cost are wires to transmit .. then at the end of distance step down transformer is used for commercial use.
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211 views
4 answers
asked
Aug 25, 2019
by
anonymous
when charging a battery we use a DC supply but not an AC supply. Why ?
Last Answer : When power is supplied to the battery, electrolyte inside the battery is divided into positive and negative ions, where ions with similar pole is gained in one side. This reactionʼs flow coincides with direct current.
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103 views
1 answer
asked
Aug 21, 2019
by
anonymous
Why can't we store AC in batteries instead of DC ?
Last Answer : Because the direction of the current changes in AC electricity, you cannot directly store the power. Placing a capacitor in an AC circuit has no effect on the alternating flow of the electricity. The only ... is indirectly, by storing DC and then using a power inverter to convert the DC to AC.
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116 views
3 answers
asked
Aug 19, 2019
by
anonymous
What would happen if a DC motor was supplied with AC ?
Last Answer : With three phase induction motor, humming and not rotate, but if single phase universal motor like air blower, home mixture, motor run on constant speed..speed variation not possible...
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122 views
2 answers
asked
Aug 18, 2019
by
anonymous
What is the conversion between. AC to AC ? DC to DC? AC to DC? DC to AC ?
Last Answer : 1.ac to ac is regulation 2.dc to dc is chopper 3.ac to dc is rectifier 4.dc to ac is inverter
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101 views
1 answer
asked
Aug 15, 2019
by
anonymous
Why the Led Glow in Dc Supply ? Whenever give the Ac Supply What is Affect in Led ?
Last Answer : LEDs consume DC current to produce light; with AC current the LED will only be lit when current flow is in the proper direction. AC applied to an LED will cause it to blink on and off, and at high frequency the LED will appear to be lit continuously.
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84 views
1 answer
asked
Aug 12, 2019
by
anonymous
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Is the power line voltage available in our homes a dc or an ac voltage?
Last Answer : The power line voltage available in our homes is AC. Mobile dwellings are the most commonly DC-supplied homes and even then they tend to include AC supply for heavier loads.
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5.2k views
1 answer
asked
Jun 29, 2019
by
anonymous
Compare AC & DC track circuits on i) Length of circuit ii) Application iii) Effect of stray currents. iv) Maintenance
Last Answer : Ans: i) Length of circuit - a) AC track circuit is having long length upto 3 to 5 km b) DC track circuit is having short length ii)Application -a) AC track circuit is used ... ) Maintenance - a) AC track circuit has easier and cheaper maintenance b) DC track circuit has complicated maintenance
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103 views
1 answer
asked
Sep 2, 2018
by
anonymous
Distinguish between AC and DC.
Last Answer : Particulars Direct Current Alternating Current Definition It is the current whose magnitude and direction do not change with respect to time. It is the current whose ... system, electroplating, Battery charging, Traction. AC machines, Domestic and industrial supply.
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464 views
2 answers
asked
Aug 8, 2018
by
anonymous
In practice, a current source inverter consists of an AC/ DC converter with a large inductance ‘L’ in the output. This inductance maintains a ……… …………through the switching devices over short interval of time. A) constant current B) constant voltage C) constant power D) none of the (A), (B), (C)
Last Answer : In practice, a current source inverter consists of an AC/ DC converter with a large inductance ‘L’ in the output. This inductance maintains a constant current through the switching devices over short interval of time.
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85 views
1 answer
asked
Jun 17, 2018
by
anonymous
AC supply system compared to DC supply system has the advantage:
Last Answer : AC supply system compared to DC supply system has the advantage: low cost of switching
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51 views
1 answer
asked
May 22, 2018
by
anonymous
The main advantage of AC over DC is: (A) Conversion flexibility from one voltage level to other (B) AC can be easily converted into DC by using a rectifier (C) AC is easy to maintain & can be easily distributed at long distances (D) All of the above
Last Answer : Ac is easy to maintain and ac can be easily converted to dc by rectifier .There is no commutator for conversion in ac that's why ac machines are weight less and more efficiency.ac machines occupy less space than dc .
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144 views
2 answers
asked
May 8, 2018
by
anonymous
Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above
Last Answer : Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above
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186 views
1 answer
asked
Apr 29, 2018
by
anonymous
In a dc-ac 3-phase MOSFET bridge inverter circuit, the switches are marked in a sequence as 1, 2, 3 in the top-half and 4, 5, 6 in the bottom half of the bridge. The triggering sequence of switches that gives balanced output voltage is (A) 1 ... 3, 4, 2, 6 (C) 1, 6, 2, 4, 3, 5 (D) 1, 4, 2, 5, 3, 6
Last Answer : In a dc-ac 3-phase MOSFET bridge inverter circuit, the switches are marked in a sequence as 1, 2, 3 in the top-half and 4, 5, 6 in the bottom half of the bridge. The triggering sequence of switches that gives balanced output voltage is 1, 6, 2, 4, 3, 5
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102 views
1 answer
asked
Apr 25, 2018
by
anonymous
A large dc motor is required to control the speed of the blower from a 3 -phase ac source. The suitable ac to dc converter is, 3 -phase (a) Fully controlled bridge converter ( ... bridge converter with freewheeling diode (c) Half controlled bridge converter (d) Converter pair in sequence control
Last Answer : a fullu control
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171 views
2 answers
asked
Apr 25, 2018
by
anonymous
A single phase fully controlled thyristor bridge ac -dc converter is operating at a firing angle of 25 degree and an overlap angle 10 degree with constant dc output current of 20A. The fundamental power factor (displacement factor) at input ac mains is : (A) 0.78 (B) 0.827 (C) 0.866 (0) 0.9
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159 views
0 answers
asked
Apr 14, 2018
by
anonymous
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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
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134 views
1 answer
asked
Apr 12, 2018
by
anonymous
Which method is not used for conversion of AC to DC? A. Motor-generator set B. Rotary converter C. Metal rectifiers D. Dynamometers
Last Answer : Dynamometers method is not used for conversion of AC to DC.
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137 views
1 answer
asked
Apr 12, 2018
by
anonymous
To enable dc series motor work satisfactory with an AC supply, the following modifications should be done (1) The yoke and poles should be completely laminated (2) The poles should be made of ... (3) The air gap between stator and rotor be reduced (4) Compensating poles should be introduced
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152 views
0 answers
asked
Apr 11, 2018
by
anonymous
A dc series motor when connected across an AC supply will (1) Develop torque in same direction (2) Not develop any torque (3) Draw dangerously high current (4) Develop a pulsating torque
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91 views
0 answers
asked
Apr 11, 2018
by
anonymous
Which of the following device converts DC to AC? A) Rectifier B) Boost converter C) Transformer D) Inverter
Last Answer : Reflector
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1.1k views
5 answers
asked
Apr 9, 2018
by
anonymous
Do cell phones use AC or DC current?
Last Answer : DC of course.
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210 views
2 answers
asked
Mar 14, 2018
by
anonymous
Is current from a battery AC or DC?
Last Answer : The current from the battery is DC
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135 views
2 answers
asked
Mar 14, 2018
by
anonymous
Last Answer : Igbt alone cant convert dc to ac. igbt half bridge or full bridge or three phase topology could be used to convert dc to ac. also igbt gates should be driven by microcontroller or pwm/spwm gate driving signals ... e4(-) and g4 c2e1 and c4e3 pins are AC output pins. its name is igbt inverter.
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189 views
1 answer
asked
Feb 24, 2018
by
Amit Sharma
why ACcurrent is smaller than DC current
Last Answer : AC current is not always smaller than DC.
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136 views
1 answer
what is the difference between AC and DC current ?
Last Answer : AC is generated using Alternator. DC is generated using DC generator. AC changes its direction periodically. DC do not change its direction periodically. AC have non zero frequency. DC have zero ... Power factor of AC is between 0 and 1. But power factor of DC is always 1.
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154 views
1 answer
are AC and DC resistances same?
Last Answer : Resistance is the ability of a circuit or element (which is called resistor) to oppose current. Examples of Resistors with the ability of high resistance are Wood, Air, Mica, Glass, Rubber, Tungsten ... constant. Therefore, only the original resistance of wire comes into play. they are not the same
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82 views
1 answer
asked
Oct 18, 2017
by
anonymous
which is dangerous AC or DC ?
Last Answer : DC is more dangerous than AC. Because there is lowering of voltage and current in AC but in DC it is continuous or pulsating which is dangerous than AC.
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94 views
1 answer
asked
Aug 15, 2017
by
anonymous
In which year did G.S. Ohm formulate Ohm’s law?
Last Answer : Answer: 1827.
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0 views
1 answer
asked
Jan 31
by
anonymous
What is Ohm Law ?
Last Answer : ohm law : current flowing through a conductor at constant temperature সম proportional to the voltage difference between the two ends of the conductor and disproportionate to the resistance " Explanation " , But according to Ohm's formula I = V / R i.e. V = IR
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0 views
1 answer
asked
Jan 28
by
anonymous
