A straight wire of length 0.20 m is stretched horizontally so that it makes an…
MATHEMATICS · Multi-part · ISC · Mathematics · Physics · Magnetic Effects of Current and Magnetism
Problem
A straight wire of length 0.20 m is stretched horizontally so that it makes an unknown angle θ with the geographic north–south direction. A horizontal magnetic field of 0.40T acts from east to west. When a current of 12 A is passed through the wire, the magnitude of the upward force on it is measured to be 0.50N.
Work through the following tasks sequentially.
(a) Calculate the value of θ.
(b) Without altering the direction of current, the wire is now rotated until it becomes perpendicular to the magnetic field. Find the new magnitude of the force.
(c) Explain briefly why the force would become zero if the wire were aligned exactly along the direction of the magnetic field.