# Electronics - Alternating Current and Voltage - Discussion

Discussion Forum : Alternating Current and Voltage - General Questions (Q.No. 5)

5.

A half-cycle average voltage of 12 V is equal to what rms voltage?

Discussion:

24 comments Page 2 of 3.
Manish yadav said:
7 years ago

We are not use half wave formula because in electrical method also use full wave formula because in case of electrical we are use in wark 5volt minimum value and more than,

5volt <12volt. So we are useful wave formula.

Iavg.=12volt,

Im=12*3.14÷2=18.84

Irms=18.84÷1.41=13.36.

5volt <12volt. So we are useful wave formula.

Iavg.=12volt,

Im=12*3.14÷2=18.84

Irms=18.84÷1.41=13.36.

Rahul yadav said:
7 years ago

Yes, you are correct @Pawn.

Pawan said:
7 years ago

It is, 18.84.

KIRAN V said:
7 years ago

Given;

V avg = 12 V.

Formula taken w.r.f to Full wave rectifier.

Vavg = 2*V max / pi.

Vmax = (V avg * 3.14)/2.

Vmax = (12 * 3.14)/2.

Vmax = 18.84 V.

Vrms = V max /sq.root of (2).

Vrms = 18.84 /1.414.

Vrms = 13.323 V.

V avg = 12 V.

Formula taken w.r.f to Full wave rectifier.

Vavg = 2*V max / pi.

Vmax = (V avg * 3.14)/2.

Vmax = (12 * 3.14)/2.

Vmax = 18.84 V.

Vrms = V max /sq.root of (2).

Vrms = 18.84 /1.414.

Vrms = 13.323 V.

SAs said:
8 years ago

For half cycle.

Effective voltage or RMS = 1.11*V average.

= 1.11*12 = 13.32 v.

Effective voltage or RMS = 1.11*V average.

= 1.11*12 = 13.32 v.

Engineer Marc said:
9 years ago

This is wrong. If you use full wave formula:

Valve = 2Vpeak/3.1416 => 12 = 2Vpeak/3.14160 (Shift solve).

Vpeak = 18.8496 (full wave).

For full wave Vrms:

Vrms = Vpeak/sqrt 2 = 18.8496/sqrt 2 = 13.13 (Vrms for full wave).

The correct formula for half wave is:

Valve = Vpeak/3.1416 => 12 = Vpeak/3.1416 (Shift solve).

Vpeak = 37.6992.

For Vrms half wave its:

Vrms = Vpeak/2 => 37.6992/2 = 18.84.

Valve = 2Vpeak/3.1416 => 12 = 2Vpeak/3.14160 (Shift solve).

Vpeak = 18.8496 (full wave).

For full wave Vrms:

Vrms = Vpeak/sqrt 2 = 18.8496/sqrt 2 = 13.13 (Vrms for full wave).

The correct formula for half wave is:

Valve = Vpeak/3.1416 => 12 = Vpeak/3.1416 (Shift solve).

Vpeak = 37.6992.

For Vrms half wave its:

Vrms = Vpeak/2 => 37.6992/2 = 18.84.

Vinod semwal said:
1 decade ago

Vpick = pai* Vavrag/2.

Vpick = 3.14*12/2.

= 18.84.

Vrms = Vpick/1.414.

= 18.84/1.414.

= 13.33 V.

Vpick = 3.14*12/2.

= 18.84.

Vrms = Vpick/1.414.

= 18.84/1.414.

= 13.33 V.

Stp said:
1 decade ago

Form factor Kf = (rms value/half cycle average value).

Kf for sine wave 1.11.

rms value = 1.11X12= 13.33.

Kf for sine wave 1.11.

rms value = 1.11X12= 13.33.

Sunday said:
1 decade ago

Can same formula work for rms and half cycle.

Kaneez fatima said:
1 decade ago

You all are applying formula for full cycle, but in question we asked to find rms for half cycle. If we apply formula for the half cycle answer may be wrong.

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