Ac Theory Level 1- 3rd Edition Lesson 1- Understanding inductance and how it affects a circuit

Match the term that completes the following statements.

1- Current
2-Voltage
3-Magnetic Field

When no current flows in a conductor, free electrons move ? , and their magnetic fields cancel.

A- at random

When current flows in a conductor, a magnetic field is produced. As free electrons move in one direction, their individual magnetic fields ? .

A- add together

The important factors needed for generation of an induced voltage are a conductor, a magnetic field, and ? .

C- relative motion

Select the correct option to complete the following sentences.

1- decrease
2- increase

When a conductor moves through a stationary magnetic field an EMF is induced, but when the magnetic field moves and the conductor remains stationary no EMF is induced.

B- false

Whenever an electric current flows through a conductor, a magnetic field is formed ? the conductor.

B- around

? Law states that an induced voltage or current opposes the motion that causes the induced voltage or current.

C- Lenz's

Inductors always oppose a change of ? .

A- current

Counter Electromotive Force is sometimes called back EMF, and CEMF is ? out-of-phase with the applied voltage.

B- 180 degrees

CEMF ? the applied EMF when current is increasing and ? the applied EMF when current is decreasing.

C- subtracts from/ adds to

Which items listed below are factors that work in combination to affect the inductance produced by an inductor.

D- I, II, III, IV

Drag the appropriate term to the correct schematic symbol.

Iron Core Inductor/ Air Core Inductor

The rate of current change in an inductive circuit can be described as a(n) ? curve.

C- exponential

How many time constants does it take for current to reach its maximum value in an inductive circuit?

B- 5

At what percentage is the current after one time constant when the circuit is first energized?

D- 63.2% of maximum

The unit of inductance is the ? , and inductance is represented by the letter ? .

A- henry/ L

f a change of one ampere in one second causes one volt to be induced, you have ? of inductance.
Select one:

A- one henry

In high frequency applications, ? inductors are used because of eddy current loss and hysteresis loss in the core material.

A- air core

n the formula for inductance, match the letter to what it represents.

1- A
2-I
3-N
4-u

Match the term that completes the following statements.

directly, inversely, directly, directly

What is the formula for determining the time constant in an inductive circuit?

D

Calculate the amount of time it will take for the current to reach its maximum value in a circuit having 125 millihenries of inductance and 50 ohms of resistance.

.0125 Seconds

The circuit shown has a total current of 3 amperes. What is the approximate current at two time constants (It2)?

B- 2.59 A

Given the formula for determining the counter EMF (induced voltage of a coil), drag the variables to the statement they represent.

I
T
L
CEMF