Comparing Current, Force, B Field, Magnetism

[bmb2009]

Homework Statement

Please see the attachment and see where i went wrong... simple T/F questions

Homework Equations

The Attempt at a Solution

Here's what i tried

1. T (Right hand rule for both I1 and I2 where I2=-I1
2. F (Since I2 has no current, there is no B field from I2 so the B field is from the right hand rule of I1 making the field point down)
3. T There is no force on the particle if there is no velocity
4. T (force is perp to the b Field and since the B field point s down, force must be into the page
5. F again force should be into the page
6. T b field from I2 is out of the page so th froce is perpendicular making it point down
7. T Opposite force directions should make the lines repel?

PLEASE HELP

 

[anathema]

Hi there,

It looks like you have the right idea for most of these questions! Here are some corrections and explanations for the ones you got wrong:

1. T is correct. The right hand rule applies to both I1 and I2, so since I2 is equal and opposite to I1, its magnetic field will also be equal and opposite.
2. F is incorrect. Both I1 and I2 contribute to the overall magnetic field at the location of the particle, so the B field cannot be determined using just the right hand rule for I1.
3. T is correct. The particle will only experience a force if it has a velocity perpendicular to the magnetic field.
4. T is correct. The force on the particle will be perpendicular to both the velocity and the magnetic field, and since the B field is down, the force will be into the page.
5. F is incorrect. The force will still be into the page, as explained in the previous question.
6. T is correct. The B field from I2 is out of the page, so the force will be perpendicular to both the velocity and the B field, making it point down.
7. T is correct. Since the forces on the particle are in opposite directions, they will repel each other.

I hope this helps! Let me know if you have any further questions.