HSC Stuff > HSC Physics
Electromagnetism (Generator Effect)
Jefferson :
Hi all,
Could I receive some clarity for the following question (in attachment).
"For each wire ... label the +ve and -ve ends".
Taking (i) as an example,
* The conductor is moving upwards.
* Magnetic field is into the page.
* Therefore, the direction of the induced current is from right to left (using whichever hand rule).
From this point, I'm not sure which side will be positive/negative.
Given that electrons flow from the left to right (opposite to conventional current), is it:
(a) The right side will be negative, because that's where all the electrons will end up (i.e. they move to the right to make it negative).
∴ Left is positve, right is negative.
or
(b) The induced emf makes the right side positive, which is why the electrons will move there (i.e. the electrons are attracted to the right because it's positive)
∴ Left is negative, right is positive.
Also, does the "assume the circuit is completed externally" play any part in this answer?
fun_jirachi:
Hey there!
Not too sure, but for i) the velocity is up, the field is into the page and then by the right hand palm rule the conventional current moves to the right. Since the flow of conventional current is right, then I'd assume the right is negative and the left is positive.
Jefferson :
--- Quote from: fun_jirachi on February 04, 2019, 04:23:54 pm ---Hey there!
Not too sure, but for i) the velocity is up, the field is into the page and then by the right hand palm rule the conventional current moves to the right. Since the flow of conventional current is right, then I'd assume the right is negative and the left is positive.
--- End quote ---
Hi, I think the right hand palm rule is used to determine the force produced from the motor effect.
To get an induced current, you would use another rule (generator effect).
fun_jirachi:
I still use the right hand rule for that, but I orientated my hand wrong. :'(
So basically, the conventional current should go left. (my bad)
In that case, the opposite is true; ignore everything I just said :'( :D. What this means is that because conventional current goes left, the flow of negative charge is to the right, and in that case b) is true.
Sorry for the mistake :'(
Jefferson :
--- Quote from: fun_jirachi on February 04, 2019, 05:51:53 pm ---I still use the right hand rule for that, but I orientated my hand wrong. :'(
So basically, the conventional current should go left. (my bad)
In that case, the opposite is true; ignore everything I just said :'( :D. What this means is that because conventional current goes left, the flow of negative charge is to the right, and in that case b) is true.
Sorry for the mistake :'(
--- End quote ---
Hi again,
That's what I thought as well, but I've been getting conflicting answers from different people.
One diagram that supports (a) is this one (in attachment), which shows the electron moving towards the positive pole of the conductor.
Edit: Attachment 2 says otherwise.
Edit 2: Attachment 3 comes with an explanation :O.
Navigation
[0] Message Index
[#] Next page
Go to full version