# 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 1 of 3.
Ram said:
1 decade ago

Imax=Irms/1.414

Imax=1.57*Iav

Imax=1.57*12=18.84

Irms=18.84/1.414

Irms=13.33V

Imax=1.57*Iav

Imax=1.57*12=18.84

Irms=18.84/1.414

Irms=13.33V

Karuppasamy kpk said:
1 decade ago

RMS value = V(peak value)*.707

V(average value)= Vpk*.637

Therefore, RMS valu =Vav*(.707/.637)

Vrms = 12*1.11 = 13.31= 13.33.

V(average value)= Vpk*.637

Therefore, RMS valu =Vav*(.707/.637)

Vrms = 12*1.11 = 13.31= 13.33.

Vid said:
1 decade ago

Why we are not directly taken formula for half wave rectifier.

Form factor= (rms/avg).

Form factor= (rms/avg).

Abhi said:
1 decade ago

Avg.value = 0.636*Max.value.

Max.value = 12/0.636 = 18.86.

but,

RMS value = Max.value/1.414.

RMS value = 18.86/1.414=13.34.

So, the option is [A].

Max.value = 12/0.636 = 18.86.

but,

RMS value = Max.value/1.414.

RMS value = 18.86/1.414=13.34.

So, the option is [A].

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.

Sunday said:
1 decade ago

Can same formula work for rms and half cycle.

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.

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.

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.

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.

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