Level 2 Module 1 Alternating Currents

2:1

What is the step-down turns ratio of a transformer with 200 turns in the primary and 100 turns in the secondary?

induced high voltage

Opening the secondary of a CT under load will cause a dangerous level of___.

40Hz

What is the hertz rating of an AC circuit if the frequency is 20 cycles per 1/2 second?

340V

Given: A circuit has an rms voltage of 120VAC. What is the peak-to-peak voltage?

175V

A circuit has a peak voltage of 275V. What is the average voltage value?

one-third the applied voltage

Each of three equal capacitors in series has___.

XL=2piefL

The formula for inductive reactance is___.

10A

Given: An AC circuit containing resistance only. What is the current flow if the resistance is 15 ohms and the voltage is 150v?

Lags the voltage

The current in inductive circuit___.

Rms values

Unless otherwise noted, the calculations in AC circuits use___.

Increases

When frequency decreases, capacitive reactance___.

It leads the voltage.

Which of the following is true of the current in a capacitive circuit?

0.637 x peak value

In sine wave terminology, the average value is___.

All DC rules and laws apply, including Ohm's law

In AC circuits containing only resistance,___.

Increases

If the area of the plates of a capacitor is increased, the amount of capacitance___.

Current with respect to time

The self-induced voltage across in inductance is equal to the change in___.

45

Given: A 30-microfarad capacitor in parallel with a 15-microfarad capacitor. The total capacitance is___.

Inductance

Which of the following opposes any change in circuit current?

Phase relationships that exist between voltage and current in an inductive circuit

"ELI the ICE MAN" is used to remember___.

Greater than the true power

According to the power triangle, the apparent power is___.

Transformer

Which of the following uses electromagnetic induction to transfer electrical energy from one circuit to another?

75V AC

Given: A transformer has 200 turns in the primary, 100 turns in the secondary, and 150V AC applied to the primary. What is the voltage across the secondary?

Unlike-wound transformers

Transformers in which the primary and secondary voltages are 180 out of phase are known as___.

Across the field at 90°

Maximum voltage is generated by rotating wire when the conductor is moving___.

10 Hz

If the time for one cycle is 0.1 second, the frequency is___.

Are in phase

If the phase angles of two sine waves are both 0 degrees then the waves___.

400W

Calculate the true power in a 2A series RL circuit with a 100 ohms resistor.

Frequency increases

Inductive reactance increases as the___.

Apparent power

The power factor can be defined as the ratio of true power to___.

Increasing capacitance

For a given frequency, the capacitive reactance decreases with___.

By some angle between 0° and 90°

In a circuit that has both capacitance and resistance, the current will lead the voltage___.

Are 90° out of phase

If the vector diagram of two AC waveforms is a right angle, then the waves___.

Zero

In an inductive AC circuit, when the applied voltage is at its maximum negative value, the current is___.

Apparent power

The product of the source voltage and the total current is___.

The same as the applied voltage

In a parallel LC circuit, the voltage across the branches is___.