What is the direction of the magnetic field that produces the magnetic force shown on the currents in each of the three cases in Figure${}^{\mathbf{22}\mathbf{.}\mathbf{55}}$, assuming ${}^{\mathbf{B}}$is perpendicular to${}^{\mathbf{I}}$?

The right-hand rule can be used to identify the current direction. Therefore, if the palm of the right hand is aligned to the force direction, the thumb is in the direction of the current, then the magnetic field direction can be obtained from the direction of the fingers.

(a)

Observe that the force is pointing to the left and the current is pointing upwards. So, the field is said to be pointing to the page (inwards).

(b)

Observing that the force is pointing into the page and the current pointing downwards. So, the field is said to be pointing to the left or west direction.

(c)

Observing that the force is pointing upwards and the current pointing to the right. So, the field is said to be pointing out of the page (outwards).