show that power dissipated by a pure inductor exited by a sinusoidal voltage s

show that power dissipated by a pure inductor exited by a
sinusoidal voltage source v = vm sin wt is zero

Question Posted / mckash

1 Answers
4920 Views
I also Faced
E-Mail Answers

show that power dissipated by a pure inductor exited by a sinusoidal voltage source v = vm sin wt ..

Let Vmcos(wt+X) be the voltage and Imcos(wt+Y) be the current through the inductor.
Now the power is given by
P=V*I=VmImcos(wt+X)cos(wt+Y)
By using a trigonometric identity:
P= 0.5 * VmIm * cos(X-Y) + 0.5 * VmIm * cos(2wt+X+Y)
This expression has 2 terms which both must be zero.
The first term is a constant (independent of time) but notice that in an inductor Voltage leads Current by 90 degrees so X-Y = 90 and cos(90) = 0 so first term is zero.
Now for average power integrate the above expression for a cycle and divide it by time period, since integral of every sinusoid for a complete cycle is zero the next term will essentially be zero too.

So P = 0 for an inductor.

Email me if you still have any doubt or query.
sarmadahmed@live.com

Is This Answer Correct ?

3 Yes

0 No

Post New Answer

More Electrical Engineering Interview Questions

How will be the single line diagram of series trip HT breaker? how it works?

0 Answers HAL,

Induction generator has = A negative speed B negative slip C negative voltage D negative current

2 Answers

How many battery required for an 3kva online ups with 3 hrs back up with usage of 3 fans,3tube lights

1 Answers

what is difference between earth and ground?/

3 Answers Sree Rayalseema Green Energy Limited SRGEL,

what is the distance b/w EHV lines? 1.8m 2.11m 3.4m 4.14m

7 Answers HAL,

What are the implications when the power factor is is leading condition ?

1 Answers

1. What is maximum permissible distance between smoke detectors ? 2. How do we decide number of smoke detectors required in a large office, warehouse, hall etc ? 3. What should be maximum height of smoke detectors ? 4. Where do we use heat detector, optical smoke detector, temperature sensitive detector ?

0 Answers

define differential current and restraining current in relays. how to calculate it by mathematically? post the formulaes.

4 Answers Siemens, VPEC,

how to operate and maintenance of 1500 kva diesel generator set

0 Answers Supertech,

how percentage impedence effect on the size of the power transformer?

2 Answers Bhel,

what is meant by phase &line voltage, how its differ from each other ?

5 Answers

how to make a solar panel? why solar panel cell connected to serious?

1 Answers

For more Electrical Engineering Interview Questions Click Here