Problem

A conductor

ab

of arbitrary shape carries current

I

flowing from

b

a

. The length vector

\mathbf{ab}

is oriented from

a

b

. The force

\mathbf{F}

experienced by this conductor in a uniform magnetic field

\mathbf{B}

is (a)

\mathbf{F} = -I(\mathbf{ab} \times \mathbf{B})

(b)

\mathbf{F} = I(\mathbf{B} \times \mathbf{ab})

(c)

\mathbf{F} = I(\mathbf{ba} \times \mathbf{B})

(d) All of these