why the current leads voltage in the case of a capasitor

Answers were Sorted based on User's Feedback



why the current leads voltage in the case of a capasitor..

Answer / amey

the equestion of capasitor=(q=cv)
or q=c*Vm sinwt.
now current is the rate of flow of charge.
therefore,dq/dt=c*Vm*w coswt.
i=c*Vm*w coswt.
Im sinwt=Vm/(1/wc)sin(wt-90)...........(1)
now from this equestion curent(Im) leads voltage(Vm) by
angle 90 degree.

Is This Answer Correct ?    21 Yes 0 No

why the current leads voltage in the case of a capasitor..

Answer / prasad

It must be first understood here that the capacitor
current leads the voltage across capacitor & not the supply
voltage.
Whenever A.C. voltage is applied across the capacitor,
initially free electrons start conducting current offering
zero resistance & thus no voltage across the capacitor. As
the capacitor plates start getting charged (Polarity opp to
supply) it starts offering resistance to current & voltage
starts to appear across capacitor.

Is This Answer Correct ?    13 Yes 1 No

why the current leads voltage in the case of a capasitor..

Answer / pancham

Pure capacitive circuit: capacitor voltage lags capacitor
current by 90o
pure capacitive circuit waveforms. plz plot the wave form
b/w current &voltage.

Remember, the current through a capacitor is a reaction
against the change in voltage across it. Therefore, the
instantaneous current is zero whenever the instantaneous
voltage is at a peak (zero change, or level slope, on the
voltage sine wave), and the instantaneous current is at a
peak wherever the instantaneous voltage is at maximum
change (the points of steepest slope on the voltage wave,
where it crosses the zero line). This results in a voltage
wave that is -90o out of phase with the current wave.
Looking at the graph, the current wave seems to have
a “head start” on the voltage wave; the current “leads” the
voltage, and the voltage “lags” behind the current.

Is This Answer Correct ?    13 Yes 3 No

why the current leads voltage in the case of a capasitor..

Answer / tarun aggarwal

if we say voltage at any instant is at time t

v = Vsin(wt + @ )

and we know in case of capictor
Ic = C * dv/dt

Ic = C*( Vcos(wt + @) )*w

Ic =c*w *(sint(wt + @ + 90) )
this clearly show that current leads voltage

also in case of capacitor .it start charging from zero to
full voltage while current is there to charge it which also
is physical interpretation of leading curent

Is This Answer Correct ?    9 Yes 0 No

why the current leads voltage in the case of a capasitor..

Answer / deepakindi1

current through capacitor=

ic= c dvc/dt

ie current through capacitor is a function of rate of
change of voltage applied across it, as applied voltage is
sinusoidal sine wave ,if u take a slope at zero croosing of
wave form rate of change of the voltage is maximum so is
the current at zero croosing of wave form is maximum. that
ic reaches its maximum before applied voltage that y
current through capacitor leads voltage

Is This Answer Correct ?    9 Yes 1 No

why the current leads voltage in the case of a capasitor..

Answer / balaji

capacitor is nothing but two metallic plates seperated by a
dielectric medium..if we give supply to a capacitor the
flow of oppositely charged particles begin results in the
flow of current resembles like short circuit.voltage in a
short circuit is zero...once the metal plates get charged
no particles will move and it behaves like a open circuit
having supply voltage across it and the current becomes
zero.

Is This Answer Correct ?    6 Yes 5 No

why the current leads voltage in the case of a capasitor..

Answer / kumar.shyam1

capacitor it stores the energy in the form of static field
and when no magnetic field no change of flux
so inductive part when it is a pure capacitor
from this we can say current is dominating

y it generates static field because of dielectric medium

Is This Answer Correct ?    3 Yes 6 No

why the current leads voltage in the case of a capasitor..

Answer / 5hj4rbv5v3

69omgne63gg [URL=http://www.521475.com/220668.html] 8f9r1cyymasp3kr [/URL] 6bdj47tey0

Is This Answer Correct ?    0 Yes 9 No

why the current leads voltage in the case of a capasitor..

Answer / a.balakrishnan

capacitor are always lead from voltage.Because if we give
the supply to the capacitor,at first the capacitor do
discharge,then charge.We can invent the angle of leading
from wave forms.Its leads angle may choosing of capacitor.

Is This Answer Correct ?    4 Yes 22 No

Post New Answer

More Electrical Engineering Interview Questions

i am an maintenance engineer. one distribution board have 5 feeder. recently its ELR trips frequently, but it take some times after trip( 10min,20min..)but 3 feeder no load. two feeder only loaded. i checked one feeder IR value all values are above 50Mohm.but B phase to Earth is only 9Mohm.any problem about low value

0 Answers  


How to design the NGR Resistance

0 Answers  


How are harmonics produced in AC machines?

4 Answers  


what will happen when excitation of a synchronous machine is suddenly reduce to zero when it is running at full load..??

7 Answers  


what is the highest transmission voltage in india???

49 Answers   Bhel, EIPL, Engineering, Jindal,






Why electrical heaters are not provided with overload relays in circuits

1 Answers  


Why Lighting transformers are used? what will be the current if lightings connected through direct raw power?

1 Answers   BMM,


WHAT ARE THE SITE TEST APPLIED ON A SURGE ARRESTORS? DO MEGGER TEST APPLIED ON SURGE ARRESTOR? IF YES THEN WHAT ARE THE ACCEPTED IR VALUE REQUIRED FOR SURGE ARRESTORS FOR VOLTAGE LEVEL 11KV, 33KV, 66KV 132KV, 220KV AND 400KV?

5 Answers  


On Which Pressure PRV is operated.

0 Answers   AEPL,


Can we use HRC fuse inplace of semi conductor fuse ? What are difference between them?

3 Answers  


how to find the transformer neutral copper earthing size 

1 Answers  


How earthing/grounding done in aeroplanes and ships.

0 Answers  


Categories
  • Civil Engineering Interview Questions Civil Engineering (5084)
  • Mechanical Engineering Interview Questions Mechanical Engineering (4451)
  • Electrical Engineering Interview Questions Electrical Engineering (16631)
  • Electronics Communications Interview Questions Electronics Communications (3918)
  • Chemical Engineering Interview Questions Chemical Engineering (1094)
  • Aeronautical Engineering Interview Questions Aeronautical Engineering (239)
  • Bio Engineering Interview Questions Bio Engineering (96)
  • Metallurgy Interview Questions Metallurgy (361)
  • Industrial Engineering Interview Questions Industrial Engineering (259)
  • Instrumentation Interview Questions Instrumentation (3014)
  • Automobile Engineering Interview Questions Automobile Engineering (332)
  • Mechatronics Engineering Interview Questions Mechatronics Engineering (97)
  • Marine Engineering Interview Questions Marine Engineering (124)
  • Power Plant Engineering Interview Questions Power Plant Engineering (172)
  • Textile Engineering Interview Questions Textile Engineering (575)
  • Production Engineering Interview Questions Production Engineering (25)
  • Satellite Systems Engineering Interview Questions Satellite Systems Engineering (106)
  • Engineering AllOther Interview Questions Engineering AllOther (1379)