Induced EMF and Lenz's Law (1 Viewer)

[cutemouse]

Hello,

I'm trying to get my head around Lenz's law.

And so far, I'm yet to figure out when it applies.

When you move a conductor through a magnetic field, the direction of current is given by the right hand motor rule or push rule.

But when I tried doing questions asking where the induced EMF flows, according to Lenz's law the current flows in the opposite direction to the RH motor or push rule.

Why is this?

 

[tommykins]

i'm capped so i can't open youtube.

anyways go on youtube and look up 'motors and generators' and then loook for the indian guy and a white board.

he'll explain everything to you (it was my study for motors and generators )

 

[Pwnage101]

Hello,

I'm trying to get my head around Lenz's law.

And so far, I'm yet to figure out when it applies.

When you move a conductor through a magnetic field, the direction of current is given by the right hand motor rule or push rule.

But when I tried doing questions asking where the induced EMF flows, according to Lenz's law the current flows in the opposite direction to the RH motor or push rule.

Why is this?

lenz's law - it OPPOSES the direction u see from the RHP rule

it's hard to explain over the net like this, but yeh try watchin a vid it might help

 

[scora]

i'm capped so i can't open youtube.

anyways go on youtube and look up 'motors and generators' and then loook for the indian guy and a white board.

he'll explain everything to you (it was my study for motors and generators )

is there anything youtube can't do?

 

[blaze.bluetane]

Faraday; an emf and current is induced in a conductor when there is a change in magnetic flux through the conductor
Lenz; to obey the conservation of energy, the current must be such that it produces a magnetic field that opposes the change in magnetic flux.

Otherwise, energy would be continually created since the induced current would produce a magnetic field that would intensify the changing magnetic field inducing it.
When you are doing questions, remember that induced current is opposite to the direction of normal current. The induced current must produce a field that opposes the change in flux

hope it makes sense


btw lenz's law applies when there is current [and emf] induced by a magnetic field

 

[youngminii]

Ye so it's just a law that's there so that the generator obeys the conservation of energy.
Whenever a questions asks 'which direction will the current be induced' for a generator, it's always in the opposite direction to the right hand palm rule as a result of this law.
This law doesn't apply in DC motors though so don't get confused.

 

[Tully B.]

It's not when you "push" a conductor through a magnetic field, it's when a current flows through that conductor. You can push all you want, but there won't be force without current. You could say that when you push a "current-carrying conductor" into a magnetic field, it experiences force. That works.

The only reason that I ranted about that minor error (which probably wouldn't even lose you a mark) is because I have let to have learned Lenz's law. Doing that tonight. Sorry

 

[youngminii]

Lol Tully B, you're thinking of a motor.

 

[Tully B.]

Lol Tully B, you're thinking of a motor.

No, I was talking about the general law governing a conductor within a magnetic field, and making the unneccesary comment that the conductore would have to have a current flowing through it in order to be affected by the field, and that the direction in which the conductor was "pushed" into the magnetic field had nothing to do with the field's effect on it.

 

[k02033]

No, I was talking about the general law governing a conductor within a magnetic field, and making the unneccesary comment that the conductore would have to have a current flowing through it in order to be affected by the field, and that the direction in which the conductor was "pushed" into the magnetic field had nothing to do with the field's effect on it.

Thats not true generally since an object cant possibly experience a magnetic force, if its velocity is parallel the the B field.

 

[meggo-meggo]

is there anything youtube can't do?

I think that there is nothing youtube cannot do.

its actually quite helpful in figuring out these things!! (especially motors and generators)

 

[iRuler]

I think that there is nothing youtube cannot do.

its actually quite helpful in figuring out these things!! (especially motors and generators)

+1 for youtube.

But wow, like 1 year bump?

 

[meggo-meggo]

hahah yeah, I'm a little slow with things like that... one year too late. dammit!

 

[cutemouse]

Ahh good ol' HSC Physics...