The force `vecF` experienced by a particle of charge q moving with a velocity `vecv` in a magnetic field `vecB` is given by `vecF=q(vecvxxvecB)`. Which pairs of vectors are at right angles to each other?

Options

A. `vecF` and `vecv`
B. `vecF` and `vecB`
C. `vecB and vecv`
D. `vecF and (vecvxxvecB)`

Answer

(a,b)

Explanation

The pairs `vecF,vecv and vecF,vecB` are always at right angle to each other,
because`vecF` is always perpendicular to the plane containing`vecB`
and `vecv`. Vectors `vecB and vecv` may have any angle between them.