Alternating Currents

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.

What is the phase angle between the voltages of the inductor and capacitor in a RLC series circuit?

• zero

• 90°

• 180°

• 270°

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

• 
• 
• 
• 

Quantity of charge can be measured in

• time (s)

• Ampere (A)

• coulombs (C)

• Joule (J)

The function of a generator is to change ____. 

• mechanical energy to electrical energy
• electrical energy to mechanical energy 
• electrical energy to chemical energy
• chemical energy to electrical energy 

The formula for inductive reactance is

• $\frac{1}{\omega L}$

• $\omega C$

• $\frac{1}{\omega C}$

• $\omega L$

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

• $V\ =\ V_0\ \sin\ \omega t,\ I\ =\ I_0\ \sin\left(\omega t-\frac{\pi}{2}\right)$

• $V=V_0\ \sin\ \omega t\ ,\ I\ =\ I_0\ \sin\left(\omega t\ +\frac{\pi}{2}\right)$

• $V\ =\ V_0\ \sin\omega t,\ I\ =I_0\ \sin\ \omega t$

• $V\ =\ V_0\ \sin\left(\omega t\ +\frac{\pi}{2}\right),\ I\ =\ I_0\ \sin\ \omega t$