Force on an electron in a magnetic field

[chopnhack]

Homework Statement

What is the force on an electron with a velocity v = (2i – 3j) Mms-1 in a magnetic field B = (0.8i +
0.6j – 0.4k) T

Homework Equations

F=qvBsinθ

The Attempt at a Solution

using cross product I got: (1.92i + 1.28j + 5.77k)10^-13 N which is the listed correct answer.

My question is since this was an electron, why the value wasn't negative 1.92i, etc. Wouldn't the charge have contributed to the direction? Can someone please explain this to me?
Thanks

 

[berkeman]

The sign of q in the vector qvB contributes to the sign of the cross product answer...Can you show your work including the calculation of the cross product?

 

[chopnhack]

The sign of q in the vector qvB contributes to the sign of the cross product answer...Can you show your work including the calculation of the cross product?

sure

 

[berkeman]

Yeah, your work and your answer with the "-" signs looks right to me. You are saying that the "+" answer is listed as the correct answer?

 

[chopnhack]

Yeah, your work and your answer with the "-" signs looks right to me. You are saying that the "+" answer is listed as the correct answer?

Yes, but the professor has been known to make mistakes.

 

[berkeman]

Does he/she have office hours before this is due? Show them your work and ask politely if you've missed anything...?

 

[chopnhack]

Does he/she have office hours before this is due? Show them your work and ask politely if you've missed anything...?

I have done just that. Hopefully I can get a clarification. It's very difficult to learn magnetism while correcting typos!
Thank you!

 

[berkeman]

You're welcome. Just keep doing the math, and you should be fine.