Basic Concept of A.C Generator

Suppose we have two pole maganit North and pole and one single loop coil with two wire end A and B , both are moving through some mechanical force and cutting the magnatic lines of field between the two poles. my question is both wires are moving in opposite direction so both producing emf in opposite direction.. How current flow from one side of the coil A to second side of the coil B.. i am confuse between opposite polarity or higher potential.. i am attaching one picture for reference ....

Hi Ali,

the current in each wire is in opposite direction - but each piece of wire forms opposite side of circle (the coil) - so the currents add in either a clockwise or anticlockwise direction.

Jeff

Dear Sir ,
My question is now how potential difference create in a single loop generator????

Ali,
you are requesting information on a subject which has caused millions of books to be written

here goes:

this is a DC generator

the two main components are the field and armature, (AC generator, rotor & stator)

the armature conductors cut the lines of force provided by the field

if you have one conductor, you can follow it as travels past the poles of a 2 pole stator, the conductors voltage changes as its position changes

Each field pole is equal to 180 electrical degrees, which allows you to track the location on the pole.

therefore a two pole magnetic circuit equals 360 magnetic degrees.....

at 0 degrees the voltage is 0, at 90 degrees max voltage, at 180 degrees 0 voltage, at 270 degrees max voltage at 360 degrees 0 voltage......

this holds true for both a dc or ac generator ..................

hope this helps

I forgot to mention, your drawing, in a dc generator, your left field pole would be N,
your right pole would be S, your armature would also develop N & S poles,
rotation would create attraction or repulsion,
likes repel, unlikes attract...........

when you magnetic field is established, picture stright lines between your field poles
these are the magnetic lines

these are the lines your armature conductors are cutting

draw a black dot at 0 degrees
draw a black dot at 90 degrees
draw a black dot at 180 degrees
draw a black dot at 270 degrees
draw a black dot at 360 degrees

there you have it

Part of the confusion comes from your drawing is that it over simplifies the idea. For that drawing to work properly the meter would have to spin with the A and B winding with each meter lead staying in constant contact with it's AB leg. It would produce AC OR the wire loop would alternate contact with the meter leads as it spins and would produce DC. In the DC case the switching mechanism would be called a commutator. To visualize the alternator just think of the N and S poles spinning instead of the AB loop. The needle on the meter would be alternating from left to right indicating positive and negative flow. Even though the reletive rotation of the AB loop and field has not changed the North South direction flux is reversing every 180 degrees.

The direction of electron flow is reversed if either the polarity of the flux or the direction of conductor movement is reversed

The rule of thumb is called the Right hand rule of generators and there is a corresponding Left hand rule of motors and can be fully explored here: http://en.wikipedia.org/wiki/Fleming's_left_hand_rule_for_motors

This may not be where the "rule of thumb" saying came from but it cetainly reinforced it's use.

Dear Sir,
My question is still not clear. Two wires A,B having induced voltages in opposite polarities but have same level of emf . because both have same length, velocity and magnatic field so if both have same level of emf then how potential diffrence create across the wire terminals A, B which cause the flow of current???

To be self sufficient on this matter you may want to read Electric Motors and Drives by Hughes, required reading for our students.

I am thinking you beleive the current flow in the A and B conductor is flowing in opposite directions. It is not, because the A leg is passing through the flux in one direction, let us presume up, and the B leg is passing through the flux in the opposite direction, down. You could place a + and - on each end of the AB legs. A will have the + closest to you and the B will have the - closest to you. It doesnt matter which way you do it at first, because depending on the moment you observe the rotating position, in 180 degrees it will reverse in BOTH legs. Since the AB legs are connected at the far end the current flow is in the same direction in the conductor. So the flow is + to - in A and + to - in B. The - of the A is connected to the + of the B just like you would connect batteries in series.

If this doesnt help I have misunderstood your question.

Well done Ian at last