question on magnetic fields (current carrying wires) -HSC (1 Viewer)

[jeffwu95]

I dont understand/ cant visualise how magnetic fields interact and create forces with current carrying conductors ie:

An electron is moving near a long straight wire. When a current is applied to the wire the electron experiences a force in the same direction as the current flow in the wire. What was the electrons initial direction of motion?
A. parallel to the current direction
B. Opposite to the current direction
C. Towards the wire and perpendicular to it
D. Away from the wire and perpendicular to it


Answer is C btw :s
edit: i know why it cant be A and B i just dont no whether it is C or D

 

[face34]

I did this question yesterday and I didn't understand this question as well haha.

 

[someth1ng]

The answer is definitely correct, I'll draw something on paint. Just give me a moment.

 

[someth1ng]

Using the top diagram
If the electron was moving parallel to the current, it would have a force that is towards to away from the current carrying conductor.
If the electron was moving away from the current, it would have a force that is in the opposite direction of the current.

 

[jeffwu95]

sorry why is the mag field going down :S

 

[someth1ng]

sorry why is the mag field going down :S

The right hand grip rule (or whatever you choose to call it), the circle and X in the middle denote that there is a current flowing into the page. If you're talking about the second image, it's because if you look at the space in between the electron and the conductor, the field is evidently going down the page.

 

[jeffwu95]

wait so on the left its going up but on the right its going down (mag field)

 

[someth1ng]

wait so on the left its going up but on the right its going down (mag field)

Yes, you could see it that way.

I'll make another diagram so it's clearer for you.

 

[nightweaver066]

wait so on the left its going up but on the right its going down (mag field)

Yeah, just by looking at the direction of the field lines.

 

[jeffwu95]

ohhh coolies thankyou very much haha

 

[someth1ng]

 

[jeffwu95]

thanks i get dis shit now!

 

[Come at me]

Where did you get this question from?

 

[jeffwu95]

HSC 2007 one of the multi

 

[Come at me]

HSC 2007 one of the multi

It is not I just checked

 

[jeffwu95]

hsc 2007 question 13 brahh

 

[jeffwu95]

http://www.boardofstudies.nsw.edu.au/hsc_exams/exam-papers-2007/pdf_doc/physics-07.pdf 13!!!!!