Is the charge positive when the AC cycle is at the top and negative when the cycle is at bottom?

Question

Is the charge positive when the AC cycle is at the top and negative when the cycle is at bottom?

Answer 1

Yes

Answer 2

yes,it is positive at top and negattive at down

Answer 3

This is the normal convention, but there's no theoretical reason why it couldn't be the other way around!

Generally speaking in electrical work, "up" corresponds to "more positive". However, if an electronic circuit is powered from a negative dc supply (e.g. a -48V telecoms supply), this is sometimes drawn at the top of the schematic diagram and can be very confusing!

Also the very term "positive" is misleading, since electrons carry negative charge! Unfortunately the original workers got it the wrong way round, so conventional current flows in the opposite direction to electrons. Very odd, but we're stuck with it.

Answer 4

Top = positive

Bottom = negative.

The normal flow of electrons is from the + pole to the negative pole (Ben Franklin got it backwards).

When a generator creates power it does so in pattern or positive and negative; flip-flopping between each one as the rotor turns in the magnetic field.

We graph the power with a sine wave that runs from the value of 0 volts to a high of around 110-120 volts back to a low of zero and then to a value of -110-120 volts, back to zero and then repeating the cycle going up to a high of 110-120 volts all done at the rate of 60 cycles per second (60 hertz); at least in the US.  In Europe voltage is generated at 50 hertz between the values of 220-240 volts.

For domestic power several generators are put on line slightly out of phase so that the voltage will be at a more constant value instead of at a fluxing value.  The additional generators are set to come to their peak power output when one generator is running at zero so the average power remains between 110-120 volts in the US.  If you had a DC volt meter hooked up then the needle would swing back and forth 60 times per second.  Which is fast enough that it would be a unrecognizable blur.

Images broadcast on American TV are broadcast as still images 60 times per second which seems to make the images move.  American electric clocks also vibrate at 60 cycles a second.  The voltage on the power line can flux as high or low as 20 volts, but the cyclic rate remains constant.  (In Europe the clocks and TV signals are set for 50 cycles per second).