In AC analysis do I alternate the current and voltage?

[Boltzman Oscillation]

Lets say I am analyzing a simple AC voltage source with a resistor. In the positive voltage peak then I will use V and I say current is flowing clockwise. When I am analyzing the -Vpk iteration then do I make the current counter clockwise too or do i keep it clockwise? Thanks.

 

[BvU]

Better to keep one orientation and use negative numbers for the quantities

 

[Boltzman Oscillation]

Better to keep one orientation and use negative numbers for the quantities

Hmm usually when I do KCL I equate the sum of all of the components with +/- polarity to the sum to all of the components with -/+polarity. Where would an AC source fit in here? How will I know if it is a voltage drop or voltage rise since it has no polarity?

 

[BvU]

I don't understand. It has polarity, just alternating. KCL is indepenent of the choice of polarity: the sum comes out zero one way and the other way too.

 

[anorlunda]

Lets say I am analyzing a simple AC voltage source with a resistor. In the positive voltage peak then I will use V and I say current is flowing clockwise. When I am analyzing the -Vpk iteration then do I make the current counter clockwise too or do i keep it clockwise? Thanks.

We usually do it with plus and minus signs as @BvU said, but yes you can consider it as alternating between clockwise and counter-clockwise if you wish.

 

[Windadct]

In a cricuit diagram we typically indicate the current polarity with an Arrow at a given point in the circuit. So when the value at this point is Negative, the current is flowing in the opposite direction.

 

[jim hardy]

Lets say I am analyzing a simple AC voltage source with a resistor. In the positive voltage peak then I will use V and I say current is flowing clockwise. When I am analyzing the -Vpk iteration then do I make the current counter clockwise too or do i keep it clockwise? Thanks.

I'm confused.

Have you drawn two separate circuit diagrams ? One for each polarity of applied voltage?
Then treat them as two separate analyses and assign polarities and arrows however you are accustomed.
After all at any instant AC has only one direction..

In classical AC circuit analysis we assign arrows and signs just as in DC analysis
but our voltages and currents are expressed not as simple numbers but A_mplitude X sin(2πf_requency X time)

so their directions reverse themselves as you evaluate sin(2πf_requency X time ) .
because sin function swings between -1 and +1

You'll see (2πf_requency X time ) usually written as ωt,
ω being 2πf_requency
and t being time.

make sense?

 

[Baluncore]

How will I know if it is a voltage drop or voltage rise since it has no polarity?

You will know that it alternates. KCL is not interested in time.
An AC voltage is usually represented by a sinewave. When you multiply a sinewave by a negative number the sinewave turns upside down. For a sinewave that is equivalent to a phase shift of 180°.
You do not need to analyse the negative side of an AC signal. You analyse for the positive signal, then where it has a negative sign, you know the signal is inverted.

 

[anorlunda]

Lets say I am analyzing a simple AC voltage source with a resistor. In the positive voltage peak then I will use V and I say current is flowing clockwise. When I am analyzing the -Vpk iteration then do I make the current counter clockwise too or do i keep it clockwise? Thanks.

It is also analogous to a DC circuit where you reverse the polarity of the DC battery source.