Multiple choice, magnetic force on the particle

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Mdhiggenz
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Homework Statement



Multiple-choice physics question A27.3 about the magnetic force on a particle with charge -1 C moving at 5 m/s in +z, with B = (3i - 4j) T; options A to E, with D checked in red.



Homework Equations





The Attempt at a Solution



I know that since the charge is negative qo*Vperpendicular would be traveling in the oppsite direction. Which by the right hand rule ultimately affects B.

So using the formula F=q0V(perpendicular)*B

= 1*5(4i-3j)
= (20i-15j)

I don't understand why the answer would be D.

Or maybe my approach to the problem was incorrect?

Thanks
 
The equation is [itex]\vec{F}=q\vec{v}\times\vec{B}=-1C*5\hat{k}\frac{m}{s}\times(3\hat{i}-4\hat{j})T[/itex]. What is [itex](-1)(-4)\hat{k}\times\hat{j}[/itex]?