search
person
are AC and DC resistances same?

1 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 etc.
Unit of Resistance is “Ohm” and it is denoted by Ω and it is represented by “R”.
AC Resistance
In Simple words, Resistance in AC circuits is called Impedance. Or
The Overall resistance (Resistance, Inductive reactance and Capacitive reactance) in AC circuits is called Impedance (Z)
DC Resistance
We know that there is no concept of Inductive and Coactive reactances in DC Circuits. i.e. capacitive and inductive reactances in DC circuits zero  because there is no frequency in DC circuits, i.e. magnitude of DC current is constant. Therefore, only the original resistance of wire comes into play.
they are not the same
thumb_up_alt 0 like thumb_down_alt 2 dislike
Capacitive reactance in DC circuit is not 0, it is actually infinite.

Xc=1/(2*pi*f*C)

Related questions

Description : Why are DC motors used in trains and not AC motors ?

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.

Description : Which is more dangerous AC or DC and why ?

Answer : Dc is more dangerous than Ac because in Ac the voltage  will varies but in dc the constant voltage 

Description : Distinguish between AC and DC.

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.

Description : 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

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

Description : What is the advantage of AC over DC electrical transmission?

Description : Why is AC considered more efficient than DC?

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.

Description : What is the conversion between. AC to AC ? DC to DC? AC to DC? DC to AC ?

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

Description : Is the power line voltage available in our homes a dc or an ac voltage?

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.

Description : 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

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 .

Description : Do cell phones use AC or DC current?

Answer : DC of course.

Description : Is current from a battery AC or DC?

Answer : The current from the battery is DC

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.

Description : Compare the AC and DC Arc lamps.

Answer : AC Arc Lamp DC Arc Lamp Cross section area of electrode is same Cross section area of electrode is positive rod is twice that of negative rod Series inductor is used for stability ... supply is used for DC arc lamp Luminous efficiency is less Luminous efficiency is high

Description : What is the difference between an AC and DC generator?

Answer : The generator which generates DC voltage is called DC generator and generator which generates AC voltage is called AC generator (or) Alternator. In DC generator armature is rotated and field winding ... generator. A DC generator can generate low voltages but an AC generator can generate upto 11kv.

Description : What is the difference between AC and DC drive?

Answer : AC means alternating current It's Frequency is 50hz Dc means direct current ItsI Frequency is 0Hz

Description : What is the use of AC and DC drives?

Description : State the modification to be done in dc series motor to work satisfactorily as ac series motor. State applications of ac series motor.

Answer : Modifications are necessary in a dc series motor so that it operates satisfactorily on ac supply. The modifications are as follows:  1) AC series motor is built with a few field turns as ... and grinders 5) High speed vacuum cleaners 6) Sewing machines 7) Food processors 8) Drilling machine 

Description : Do you think is DC better than AC to transmit energy?

Answer : In Long distance DC transmission will be better in cost. It requires more equipments for flexiblity In short distance AC transmission is better in  cost. It is more Flexible

Description : How is a thyristor used to convert AC to DC?

Description : Is electricity generated in AC or DC?

Answer : Electricity   is  generated  in  AC.

Description : Is it AC or DC electricity in the home?

Answer : Obviously its A.C

Description : Can transformer convert AC to DC?

Answer : No, Transformer cannot convert AC to DC.

Answer : NO IT ONLY CONVERT FROM AC TO DC BECAUSE DIODE WHICH ARE USED IN IT, ARE UNIDIRECTIONAL.

Answer : IT CHANGES NEGATIVE CYCLE IN TO POSITIVE CYCLE FROM AC CURRENT.

Answer : Induction motor is a AC motor it is also known as asynchronous motor .

Description : The internal resistances of an ideal current source, and an ideal voltage source are, respectively, (A) 0, ∞ (B) ∞, ∞ (C) ∞, 0 (D) 0,0

Answer : The internal resistances of an ideal current source, and an ideal voltage source are, respectively, ∞, 0

Description : Two resistances Rl and Ri are connected in series across the voltage source where Rl>Ri. The largest drop will be across?

Answer : Two resistances Rl and Ri are connected in series across the voltage source where Rl>Ri. The largest drop will be across Rl.

Description : Series parallel resistances problem solution

Answer : Series parallel resistances problem solution

Description : Accurate measurement of very low resistances is possible with (A) Megger (B) Wheatstone Bridge (C) Kelvin’s Double Bridge (D) Wagner’s Earthing Device

Answer : Accurate measurement of very low resistances is possible with Kelvin’s Double Bridge

Description :  With three resistances connected in parallel, if each dissipates 20 W the total power supplied by the voltage source equals?

Answer : Power is the only thing which is additive in both connection whether it is parallel or series connection so total power consumed will addition of all individual power =20+20+20 = 60 watt

Description : In a series circuit with unequal resistances?

Answer : In a series circuit with unequal resistances the highest resistance has the highest voltage drop.

Answer : Resistances can be measured with the help of ohmmeters and resistance bridges.

Description : Describe the difference between direct and alternating current.

Answer : Direct current is the flow of electricity or charge in one direction..  Alternative current is the flow of charge that doesn't flow in one direction. 

Description : All the rules and laws of D.C. circuit also apply to A.C. circuit containing?

Answer : All the rules and laws of D.C. circuit also apply to A.C. circuit containing resistance only.

Description : Changeover from D.C to A.C  

Answer : In later half of eighties, in nineteenth century, it was proposed to have a power system with 3- phase, 50 Hz A.C generation, transmission and distribution networks. Once a.c system was adopted, transmission of ... favor of A.C supply system own the debate on switching over from D.C to A.C system. 

Description : State any four advantages of A. C. over D. C . 

Answer : Advantages of AC over DC: i) It is possible to use a transformer. ii) Distribution efficiency is high. iii) Generation is easy and economical. iv) Construction of ac equipment/ machines is robust and simple ... . vii) AC system is economical than DC system. viii) AC system is safer than DC system.

Description : Why is AC better for long distance power transmission than DC ?

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.

Description : Why can't we store AC in batteries instead of DC ?

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.

Answer : If a D.C. motor is connected across the A.C. supply it will burn due to heat produced in the field winding by eddy currents.

Answer : A.C. series motor as compared to D.C. series motor has smaller brush width, less number of field turns, more number of armature turns, less air gap.

Answer : If a D.C. series motor is operated on A.C. supply, it will spark excessively, have poor efficiency, have poor power factor.

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

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 would happen if a DC motor was supplied with AC ?

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...

Description : Identify the increasing order of voltage regulation of the following dc generators a same load :  (A) differential compound, shunt and under compound  (B) shunt, differential compound and ... C) under compound, shunt and differential compound  (D) shunt, under compound and differential compound

Answer : Identify the increasing order of voltage regulation of the following dc generators a same load : under compound, shunt and differential compound 

Description : Alternating current (AC)

Answer : AC stands for Alternating Current meaning voltage or current that changes polarity or direction respectively over time. An Alternating Current (AC) is an electric current whose magnitude ... energy are known as alternators and are simpler construction than DC electromechanical generators.

Description : AC generator

Answer : A.C power can be generated as a single phase or as a balanced poly-phase system. However, it was found that 3-phase power generation at 50 Hz will be economical and most suitable. Present day three phase generators ... has uniform air gap (figure 2.1(b)) and used when speed is high. 

Description : Define : i) Average value ii) RMS value of an AC Wave.

Answer : i) Average value: The average value is defined as the average of all instantaneous values during one alternation . That is, the ratio of the sum of all considered instantaneous values to the ... as produced by the alternating current when flowing through the same resistance for the same time.

Description : AC Circuits with Resistance but No Reactance

Answer : AC Circuits with Resistance but No Reactance AC Circuits with Resistance but No Reactance Series resistances let two resistances R 1 and R 2 are connected in series as shows in figure and there ... voltage. Voltage V A is common to both the branch hence voltage V A is common reference.

Description : What is the need of polarity marking in polyphase AC circuits?

Answer : Need of Polarity Marking in Polyphase AC Circuits: i) Polarity marking of terminals provides reference polarity for better understanding of system, even if the polarity of ac voltage changes ... of current transformers in relay protection circuit and getting desired performance is very difficult.

← Prev Question Next Question →
editAsk a Question
...