14 Fundamentals of Electricity: Unit 14 - Magnetic Induction
The magnetic quantity Weber (Wb) is equal to 100,000,000 lines of flux. If a conductor cuts through 1 Weber per second (1 Wb/s), then a voltage of _____ volt(s) is induced into the conductor.
1
In electromagnetic induction, increasing the length of the conductor is normally done by _____.
adding more windings (make it bigger)
A coil wound around nonmagnetic core material such as wood or plastic is referred to as an _____-_____ inductor.
air-core
Since the direction of movement of a _____ field has been reversed, the induced voltage is opposite in polarity, forcing the current to flow in the same direction.
collapsing magnetic
When a conductor cuts magnetic lines of force, a voltage is induced into the conductor. This principle is called _____ _____.
electromagnetic induction (the inductor is the coil of wire).
When DC is applied to a coil, a plot of the current flow in the coil increasing from zero is a(n) _____.
exponential curve
The unit of measurement for inductance is the _____.
henry
The unit of inductance is the _____.
henry (H)
A way of determining the relationships of the motion of the conductor, the magnetic field direction, and the direction of the induced current is by using the _____.
left-hand generator
One device used for spike suppression in either direct or alternating current circuits is the _____ _____ _____.
metal oxide varistor (MOV)
The amount of voltage induced into a conductor moving in a magnetic field depends on the _____, the strength of the magnetic field, and the speed of cutting action.
number of windings
If a permanent magnet is first pushed into a coil of wire and then pulled out of the coil, the two voltages induced (one for each direction of magnet movement) will be _____.
opposite in polarity
If a voltage is being induced into a conductor by electromagnetic induction, reversing the direction of motion of the conductor will _____.
reverse the polarity
If a voltage is being induced into a conductor by electromagnetic induction, reversing the direction of the magnetic field will ____.
reverse the polarity of the induce voltage
The direction of motion is _____, the polarity of the induced current is reversed and the magnetic field created by the induced current again opposes the motion of the magnet.
reversed
* If a DC voltage is connected to an inductor, during the period of time called the first time constant, the current will rise to about _____ % of its full value.
63.2%
The amount of voltage induced into a conductor moving in a magnetic field depends on the turns of wire, the strength of the magnetic field, and the _____.
speed
The amount of voltage induced into a conductor moving in a magnetic field depends on the turns of wire, the _____, and the speed of cutting action.
strength of the magnetic field
Inductance is proportional to the number of _____ of the wire, the type of core material used, and the cross sectional area of the core, but inversely proportional to the core length.
turns
The _____ is proportional to the rate of change of current.
voltage
Losses in the core of iron core inductors include _____ and _____ losses.
Eddy current; Hysteresis
The direction of induced current can be determined by using the _____ left-hand generator rule.
Fleming's
When a closed loop of wire cuts through magnetic flux lines, a current is induced into the loop. The current in the loop sets up a magnetic field that is in opposition to the original magnetic flux. This is essentially _____.
Lenz's Law
The _____ is a bidirectional device.
MOV
In a circuit containing resistance and inductance, the time required for current to reach its full value involves a value called the _____ time constant.
R/L