ET 26201

What is the relationship of two sine waves if the vector diagram of two AC waveforms is a right angle?

• are in phase

• are 90* out of phase

• have the same frequency

• have the same peak voltage

What is the relationship of two sine waves if the phase angles are both at 0 degrees at the same time?

• are in phase

• the current lags the voltage

• the current leads the voltage

• are 90* out of phase

What is the effective voltage value of a circuit that has a peak of 310V?

• 155V

• 197V

• 219V

• 438V

Answer explanation

RMS = Effective Voltage

RMS= 0.707 x 310

RMS= 219V

If the time for one cycle is 0.02 seconds, what is the frequency?

• 2Hz

• 20Hz

• 50Hz

• 60Hz

Answer explanation

Frequency = 1 sec/time it takes to complete 1 cycle

Example: 1/.02 = 50Hz

What is one type of non sinusoidal waveform?

• sine wave

• peak wave

• sawtooth wave

• phase angle wave

Answer explanation

Page 10 in Level 2 Text Book

What is the frequency of an AC waveform that completes 25 cycles per half second?

• 12.5Hz

• 40Hz

• 50Hz

• 60Hz

Answer explanation

25hz x 2 = 50Hz

What is the total capacitance of a 20-microfarad capacitor is in parallel with a 10-microfarad capacitor?

• 10 microfarad

• 20 microfarad

• 30 microfarad

• 40 microfarad

Answer explanation

Connecting capacitors in parallel is equivalent to adding the plate area. Therefore, the total capacitance is the sum of the individual capacitances.

10mf + 20mf = 30mf

What is the opposing force that an inductor presents to the flow of alternating current?

• true resistance

• inductive reactance

• inductive capacitance

• inductive resistance

Answer explanation

The opposing force that an inductor presents to the flow of AC cannot be called resistance because it is not the result of friction within a conductor. The name given to this force is inductive reactance because it is the reaction of the inductor to AC.

What is the voltage on each of two capacitors of the same value in series?

• half

• two times

• four times

• the original value

Answer explanation

Capacitors connected in series each carry only a portion of the total voltage.

Example if 3 capacitors were connected in series each capacitor would only carry 1/3 of the total series circuit voltage.

In a circuit that has both capacitance and resistance, how will the current lead the voltage?

• always by an angle of 90*

• by some angle between 0* and 90*

• with an impedance between 0 and 1

• the resistance is too small to have any effect

Answer explanation

In resistance and capacitance circuits the current will lead the voltage by some angle between 0* and 90*.

Level 2 pg. 28