31. Alternating Current

Capacitors in AC Circuits

Multiple Choice
The peak current to and from a capacitor is i when the emf source has a peak voltage V and frequency f. What is the peak current to and from the capacitor if the frequency and peak voltage are doubled to 2f and $2 V$ , respectively?
Open Question
A 0.30 μF capacitor is connected across an AC generator that produces a peak voltage of 10 V. What is the peak current to and from the capacitor if the emf frequency is (a) 100 Hz?
Multiple Choice
An AC source operates at a maximum voltage of 120 V and a frequency of 60 Hz. If it is connected to a 175 µF capacitor, what is the maximum charge stored on the capacitor?
Multiple Choice
A 300 µF capacitor is connected to an AC source operating at an RMS voltage of 120 V. If the maximum current in the circuit is 1.5 A, what is the oscillation frequency of the AC source?
Multiple Choice
An AC circuit consists of a capacitor and an emf source with frequency $0.25 Hz$ . If the source is turned on at $t = 0 s$ , and the first time the voltage across the capacitor reaches a maximum value is at $t = 1.4 s$ , when is the first time the current in the capacitor is at a maximum?
Multiple Choice
An AC circuit consists of a $20 μ F$ capacitor and an emf source with a peak voltage of 40 V. What is the frequency of the source if the peak current is $430 mA$ ?
Multiple Choice
A low-pass RC filter has a $10 k Ω$ resistor in series with a $450 μ F$ Capacitor. What is the crossover angular frequency?
Open Question
The small transformers that power many consumer products produce a 12.0 V rms, 60 Hz emf. Design a circuit using resistors and capacitors that uses the transformer voltage as an input and produces a 6.0 V rms output that leads the input voltage by 45°.