Answer to Question #115792 in Field Theory for Odecious Gbearr

Question

A current 5A passes through a straight wire in a uniform magnitude field of a flux density 2.0 T. Calculate the force per unit length exerted on the wire when it is inclined at 30° to the field.

Answer 1

The Ampere's force

$$F_A=BIl\sin\theta$$

The force per unit length

$$F_A/l=BI\sin\theta=2.0\:\rm T\times 5\: A\times \sin 30^{\circ}=5\: N.$$