Chapter 6 Alternating Current (C1 & C2)

What is alternating current

• the process of inducing an emf (voltage) with a change in magnetic flux

• Electric currents whose direction and magnitude change periodically depending on time are called alternating current

• Steady current which delivers the same average power as the a.c. to a resistive load.

• Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor​

Which of the following general equations represent AC current

The highest value reached by the voltage or current in one cycle is called:

• Instantaneous value

• Peak to peak value

• Peak value

• Root mean square value

All of the following have the same units except:

• inductance.

• capacitive reactance.

• impedance.

• resistance.

A resistor is connected to an AC power supply. On this circuit, the current

• leads the voltage by 90°.

• lags the voltage by 90°.

• is in phase with the voltage.

• none of the given answers

A pure inductor is connected to an AC power supply. In this circuit, the current

• leads the voltage by 90°.

• lags the voltage by 90°.

• is in phase with the voltage.

• none of the given answers.

If the frequency of the AC voltage across an inductor is doubled, the inductive reactance of that inductor

• increases to 4 times its original value.

• increases to twice its original value.

• decreases to one-half its original value.

• decreases to one-fourth its original value.

Which of the following diagrams is the correct phasor diagram for V_R, V_L and V?

• 
• 
• 
• 

The equations for alternating emf and alternating current in a circuit containing capacitor are