Electric currents produce magnetic fields  Magnetism
Electric currents produce magnetic fields
Lessons
Notes:
In this lesson, we will learn:
 An electric current produces a magnetic field
 Magnetic force on a currentcarrying wire placed in a magnetic field
Notes:
An electric current produces a magnetic field
 A compass needle placed near a straight section of currentcarrying wire experience a force, causing the needle to align tangent to a circle around the wire.
 Magnetic field lines produced by a currentcarrying wire are in the form of circles with the wire at their center.
 Using righthand rule, we can find the direction of the magnetic field produced by a currentcarrying wire.
 Righthand rule: grasp the wire with your right hand, so your thumb points in the direction of the conventional ( positive) current; then your fingers will encircle the wire in the direction of the magnetic field.
Magnetic force on a currentcarrying wire placed in a magnetic field
 A straight wire is placed in the magnetic field between the poles of a magnet when a current flows in the wire, a magnetic force will be exerted on the wire.
 The direction of the force is always perpendicular to the direction of the current and also perpendicular to the direction of the magnetic field.
 Using righthand rule we can find the direction of the magnetic force.
 Righthand rules:
 Thumb points to the direction of the current,
 Fingers point to the direction of the magnetic field
 Palm points towards the direction of the electromagnetic force.
 The magnitude of the electromagnetic force (in Newton) is calculated using the following equation:
$\qquad I$ = current in the wire, in ampere (A)
$\qquad B$ = magnetic field, in tesla (T)
$\qquad \theta$ = the angle between the current direction and the magnetic field.
Note:
 When current is perpendicular to the filed lines, $\theta$ = 90°, the force is the strongest,
$F_{max} = IIB$  When the wire is parallel to the magnetic field lines, $\theta$ = 0°, there is no force at all.

Intro Lesson