Question 1

____ is an induced voltage and is, therefore, proportional to the three factors that determine induced voltage.

Accepted Answer

The three factors that determine induced voltage are the strength of the magnetic field, the rate of change of the magnetic field, and the number of turns in the coil. Inductive reactance is a measure of the opposition that an inductor offers to the flow of alternating current, and it is directly proportional to the frequency of the current and the inductance of the coil. Therefore, the induced voltage is proportional to the inductive reactance.

Question 2

Three inductors are connected in series. Inductor 1 has an inductance of 0.6 H, inductor 2 has an inductance of 0.4 H, and inductor 3 has an inductance of 0.5 H. The total inductance of the circuit is ____ H.

Accepted Answer

When inductors are connected in series, the total inductance is the sum of the individual inductances. Therefore, the total inductance is 0.6 H + 0.4 H + 0.5 H = 1.5 H.

Question 3

A total current-limiting effect is called impedance and is symbolized by the letter Z.

Accepted Answer

Impedance is a measure of opposition to the flow of electric current and is symbolized by the letter Z. It includes both resistance (symbolized by R) and reactance (symbolized by X).

Question 4

Three inductors are connected in parallel. Inductor 1 has an inductance of 2.5 H, inductor 2 has an inductance of 1.8 H, and inductor 3 has an inductance of 1.2 H. The total inductance of this circuit is ____H.

Accepted Answer

The total inductance $L_{total}$ of inductors in parallel is given by the reciprocal of the sum of the reciprocals of their individual inductances: $1/L_{total} = 1/L_1 + 1/L_2 + 1/L_3$. Plugging in the given values: $1/L_{total} = 1/2.5 + 1/1.8 + 1/1.2$. Solving this gives $L_{total} \approx 0.559$ H.

Question 5

The current-limiting property of the inductor is called reactance and is symbolized by the letter ____.

Accepted Answer

The current-limiting property of an inductor is called reactance and is symbolized by the letter X.

Question 6

Assume an inductor with a negligible resistance is connected to a 36-V, 400-Hz line. If the circuit has a current flow of 0.2 A, the inductance of the inductor is 0.0716 H.

Accepted Answer

This statement is true according to the given information.

Question 7

In a pure inductive circuit, the current lags the voltage by ____.

Accepted Answer

In a pure inductive circuit, the current lags the voltage by 90° because the inductor resists the change in current and builds up a magnetic field, which ultimately causes the current to lag behind the voltage.

Question 8

An inductor has an inductance of 0.8 H and is connected to a 120-V, 60-Hz line. How much current will flow in this circuit if the wire resistance of the inductor is negligible?

Accepted Answer

The current in an inductor can be calculated using the formula $I = \frac{V}{X_L}$, where $I$ is the current, $V$ is the voltage, and $X_L$ is the inductive reactance. The inductive reactance $X_L$ is given by $X_L = 2\pi fL$, where $f$ is the frequency and $L$ is the inductance. Substituting the given values, $X_L = 2\pi(60)(0.8) = 301.6 \Omega$. Therefore, the current $I = \frac{120}{301.6} = 0.398 A$.

Question 9

In a pure inductive circuit, the true power, or wattage, is equal to the product of the voltage and current. In a pure resistive circuit, however, no true power is produced.

Accepted Answer

In a pure resistive circuit, true power is indeed produced and is equal to the product of voltage and current, just like in a pure inductive circuit.

Question 10

The amount of ____ voltage in an inductor can be computed if the resistance of the wire in the coil and the amount of circuit current are known.

Accepted Answer

The voltage in an inductor is induced, meaning it is created by the change in current over time. The resistance of the wire will affect the overall impedance of the circuit and the amount of current flowing through the circuit will affect the rate at which the voltage is induced, but they do not directly determine the amount of induced voltage.

Question 11

The amount of induced voltage in an inductor can be computed if the resistance of the wire in the coil and the amount of circuit current are known.

Accepted Answer

The induced voltage in an inductor is directly proportional to the rate of change of current through the inductor and the inductance of the inductor. The resistance of the wire in the coil and the amount of circuit current are not directly related to the induced voltage.

Question 12

If the values of all the inductors are the same, total inductance can be found by using the following formula: LT = N / L.

Accepted Answer

The formula for calculating the total inductance of series-connected inductors with the same value is LT = NL, not N/L.

Question 13

A formula that can be used to find the total inductance of parallel inductors is LT = ____.

Accepted Answer

When two inductors are connected in parallel, the total inductance is less than either individual inductor. The formula commonly used to calculate the total inductance of parallel inductors is LT = (L1 x L2) / (L1 + L2).

Question 14

The formula for Ohm's Law is ____.

Accepted Answer

Ohm's Law states that the voltage (E) across a resistor is equal to the current (I) flowing through the resistor multiplied by its resistance (R). Therefore, the correct formula is E = I x R.

Question 15

Some amount of inductance is present in all alternating-current circuits because the magnetic field does not change.

Accepted Answer

Inductance is present in AC circuits because the magnetic field is constantly changing due to the alternating current.

Question 16

The schematic symbol used to represent an inductor depicts a coil of wire.

Accepted Answer

The schematic symbol used to represent an inductor is a coil of wire.

Question 17

Reactance is caused by inductance, so it is called reactive inductance.

Accepted Answer

Reactance can be caused by both inductance and capacitance, so it is more accurately referred to as inductive reactance when caused by inductance, and capacitive reactance when caused by capacitance.

Question 18

Since induced voltage is always in opposition to applied voltage, the applied voltage must overcome the induced voltage before current can flow through the circuit.

Accepted Answer

This is Faraday's Law of Electromagnetic Induction, which states that an induced voltage will be produced in a circuit due to a changing magnetic field. This induced voltage will always be in opposition to the applied voltage that is trying to drive the current through the circuit. Therefore, the applied voltage must overcome the induced voltage in order for current to flow.

Question 19

An electrical measurement called ____ is used to measure the reactive power in a pure inductive circuit.

Accepted Answer

The electrical measurement used to measure the reactive power in a pure inductive circuit is called VARs (Volt Ampere Reactive). Choice A (RAVs), B (AVRs), and C (VRAs) are not commonly used terms in electrical measurements.

Question 20

When inductors are connected in series, the total inductance of the circuit (LT) equals the sum of the inductances of all the inductors divided by the number of inductors.

Accepted Answer

When inductors are connected in series, the total inductance of the circuit is equal to the sum of the inductances of all the inductors. It is not divided by the number of inductors.

Quiz 3: Inductance in Alternating-Current Circuits