Question

http://apcentral.collegeboard.com/apc/public/repository/ap09_frq_physics_cem.pdf
On free response E&M. 2., part (f), it says The electrons eventually experience no deflection and move through the bar . I just don;t understand why it eventually do not experience deflection/ I appreciate in advance

Answer 1

please help! Thanks

Answer 2

Why do you think they would experience deflection?

Answer 3

Because the question says a magnetic field is applied on the rectangular thing

Answer 4

What if the electrons create their own magnetic field which cancels out the deflection, or the magnetic field wasn't oriented in a way that would affect the electrons?

Answer 5

cancels out the original magnetic field^ I meant to say

Answer 6

But the answer says it gradually get back as time goes by.

Answer 7

And the question indicate that the magetic field does influence the current

Answer 8

But if the initially deflected electrons create and electric field, wouldn't that affect the current?

Answer 9

How will it affect the current?

Answer 10

Electric fields push and pull on electrons.

Answer 11

Yes. the electron goes up, but the proton also goes to the top of the rectangular thing. Right? So they cancel out

Answer 12

Are electrons going form a to b, or b to a?

Answer 13

b to a

Answer 14

protons from a to b

Answer 15

So they all experience a force upward

Answer 16

Yep

Answer 17

Wouldn't the electrons go downward, or am I mixing up directions?

Answer 18

The electron goes upward actually

Answer 19

electron apply left hand rule rather than right hand rule

Answer 20

proton is right hand rule

Answer 21

electron is the opposite,

Answer 22

The protons are not moving charges.

Answer 23

I know, but you imagine it

Answer 24

I have never heard of a left hand rule.

Answer 25

its just the opposite of proton

Answer 26

Still right hand rule but opposite direction

Answer 27

I just call it left hand because it is all opposite

Answer 28

So since the electrons are moving from b to a, the current is moving from a to b then?

Answer 29

Yes.

Answer 30

Current is just a imaginary movement since the electron from b to a but it from a to b

Answer 31

@abb0t Can you confirm which directions the electrons are moving?

Answer 32

from b to a for sure

Answer 33

Regardless, we know that where ever the electrons are being stored in, they create and electric field which repels future electrons from building up.

Answer 34

Yes

Answer 35

This cancels out the force of the magnetic field and so they just continue to move as if none exists. Hence no deflection.

Answer 36

Oh yes. The proton does not move so no magnetic force on proton, right?