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A coil suspended within the radial field is effectively immersed in a magnetic field parallel to the plane of the coil. In these circumstances, if the coil carries current, the torque on the coil has a maximum value for that current. (See electric motor.)

^Lines o f Equipotential

Electric \ / field \ lines

^ Positive ^ point charge

radian is a unit of angle. One radian is the angle subtended at the center of a circle by an arc of length one radius. The symbol for radian is always written rad. Since the length of the circumference of a circle is 2k x radius, 360° is 271 radians.