ALTERNATING CURRENT MODULE 25:
AC CIRCUITS DYNAMIC STUDY
MODULE QUESTIONS AND ANSWERS
WTH SOLUTIONS 2024
An alternating-current (AC) source supplies a sinusoidally varying voltage that can be described with the
function v of t is equal to V times cosine of begin quantity omega times t end quantity, where V is the
maximum voltage, omega is the angular frequency, and t is the time. If the oscillation frequency of this
source is 60 Hz, what is the oscillation period? - ANSWER 1/60 s
A capacitor with capacitance C is connected in series with an AC source that provides a sinusoidal
voltage of v of t is equal to V times cosine of begin quantity omega times t end quantity, where V is the
maximum voltage, omega is the angular frequency, and t is the time. If the angular frequency of the AC
source is increased from omega to 3 times omega, what happens to the capacitive reactance, XC? -
ANSWER XC decreases by a factor of 3.
A capacitor is connected in series with an AC source that provides a sinusoidal voltage of v of t is equal to
V times cosine of begin quantity omega times t end quantity, where V is the maximum voltage, omega is
the angular frequency, and t is the time. What is true about the current that flows in the circuit? -
ANSWER The current in the circuit is out of phase with the voltage and can be described with the
function i of t is equal to negative I times sine of begin quantity omega times t end quantity, where I is
the maximum current.
A fully charged capacitor is connected in series with an inductor, as shown in the figure. When the switch
is closed to complete the circuit, the capacitor can discharge through the circuit. What is true about the
current in the inductor at the instant the capacitor is fully discharged (when Q = 0 on the capacitor)? -
ANSWER The current in the inductor is at maximum at the instant the capacitor is fully discharged.
A resistor with resistance R, a capacitor with capacitance C, and an inductor with inductance L are all
connected in series with an AC source that provides a sinusoidal voltage of v of t is equal to V times
cosine of begin quantity omega times t end quantity, where V is the maximum voltage, omega is the
angular frequency, and t is the time. If the capacitive reactance, XC, is equal to the inductive reactance,
XL, what is true about the impedance of this R-L-C series circuit? - ANSWER The impedance is equal to R.
A resistor with resistance R and an inductor with inductance L are connected in series with an AC source
that provides a sinusoidal voltage of v of t is equal to V times cosine of begin quantity omega times t end
AC CIRCUITS DYNAMIC STUDY
MODULE QUESTIONS AND ANSWERS
WTH SOLUTIONS 2024
An alternating-current (AC) source supplies a sinusoidally varying voltage that can be described with the
function v of t is equal to V times cosine of begin quantity omega times t end quantity, where V is the
maximum voltage, omega is the angular frequency, and t is the time. If the oscillation frequency of this
source is 60 Hz, what is the oscillation period? - ANSWER 1/60 s
A capacitor with capacitance C is connected in series with an AC source that provides a sinusoidal
voltage of v of t is equal to V times cosine of begin quantity omega times t end quantity, where V is the
maximum voltage, omega is the angular frequency, and t is the time. If the angular frequency of the AC
source is increased from omega to 3 times omega, what happens to the capacitive reactance, XC? -
ANSWER XC decreases by a factor of 3.
A capacitor is connected in series with an AC source that provides a sinusoidal voltage of v of t is equal to
V times cosine of begin quantity omega times t end quantity, where V is the maximum voltage, omega is
the angular frequency, and t is the time. What is true about the current that flows in the circuit? -
ANSWER The current in the circuit is out of phase with the voltage and can be described with the
function i of t is equal to negative I times sine of begin quantity omega times t end quantity, where I is
the maximum current.
A fully charged capacitor is connected in series with an inductor, as shown in the figure. When the switch
is closed to complete the circuit, the capacitor can discharge through the circuit. What is true about the
current in the inductor at the instant the capacitor is fully discharged (when Q = 0 on the capacitor)? -
ANSWER The current in the inductor is at maximum at the instant the capacitor is fully discharged.
A resistor with resistance R, a capacitor with capacitance C, and an inductor with inductance L are all
connected in series with an AC source that provides a sinusoidal voltage of v of t is equal to V times
cosine of begin quantity omega times t end quantity, where V is the maximum voltage, omega is the
angular frequency, and t is the time. If the capacitive reactance, XC, is equal to the inductive reactance,
XL, what is true about the impedance of this R-L-C series circuit? - ANSWER The impedance is equal to R.
A resistor with resistance R and an inductor with inductance L are connected in series with an AC source
that provides a sinusoidal voltage of v of t is equal to V times cosine of begin quantity omega times t end
