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________ is the magnetic effect produced when electric current flows through a conductor.
The field around a current-carrying conductor consists of magnetic rings, sometimes called _____.
When conventional (positive to negative) current flows through a conductor, the direction of the lines of force around the conductor is _______.
__________ - Imagine that you're holding a current-carrying conductor in your right hand with your thumb facing in the direction of conventional current flow. The curled fingers of your R hand now point in the direction of the lines of force, or magnetic field, surrounding the conductor.
When current flows in the same direction through two parallel wires, the wires _____ each other. When current flows the opposite direction, they _____ each other.
If a piece of insulated wire is formed into a coil, it's called a _____ coil, or a _____. When current is applied to the coil, the lines of force around each coil combine to form a larger & stronger field around the entire coil, and form N and S poles.
An ______ is made by inserting a piece of magnetic material (usually iron or soft steel) into a magnetic coil.
In an electromagnet, the material around which the conductor is coiled is called the ____.
The 3 main factors that affect the strength of the magnetic field surrounding an electromagnet are: the number of ____ in a coil, the _____ of the current, and the core's _____.
An electromagnetic ____ is a device that operates one or more switches or contact sets when current flows through its coil.
A relay's main parts are an ________ and an _____.
In a relay, the electromagnet is part of the _____ circuit, and the switching system (contacts) are part of the ______ circuit.
A _____ is a device made of a coil of wire, housing, and a moveable plunger. When current is applied, a mag. field forms around the coil and draws the plunger into the coil. When current flow stops, a spring above the plunger pushes it back into its original position.
DC motors are used in special control systems called ____ systems. These systems use feedback devices that allow a controller to precisely position the motor's shaft and control the speed of the motor.
