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