Exam 31: Electromagnetic Oscillations and Alternating Current

An LC series circuit with an inductance L and a capacitance C has an oscillation frequency f. Two inductors, each with inductance L, and two capacitors, each with capacitance C, are all wired in series and the circuit is completed. The oscillation frequency is:

In the diagram, the function y(t) = y_msin( $\omega$ t) is plotted as a solid curve. The other three curves have the form y(t) = y_msin( $\omega$ t + $\phi$ ), where $\phi$ is between - $\pi$ /2 and + $\pi$ /2. Rank the curves according to the value of $\phi$ , from the most negative to the most positive.

An RL series circuit is connected to an ac generator with a maximum emf of 20 V. If the maximum potential difference across the resistor is 16 V, then the maximum potential difference across the inductor is:

In a sinusoidally driven series RLC circuit the current lags the applied emf. The rate at which energy is dissipated in the resistor can be increased by:

A 35- $\mu$ F capacitor is connected to an ac source of emf with a frequency of 400 Hz and a maximum emf of 20 V. The maximum current is:

The total energy in an LC circuit is 5.0 *10^-6 J. If L = 25 mH the maximum current is:

An RC series circuit is connected to an emf source having angular frequency $\omega$ . The current:

When the frequency of the oscillator in a series RLC circuit is doubled:

The ideal meters shown read rms current and voltage. The average power delivered to the load is:

In a purely inductive circuit, the current lags the voltage by:

An RLC circuit has a capacitance of 12 $\mu$ F, an inductance of 25 mH, and a resistance of 60 $\Omega$ . The current oscillates with an angular frequency of:

The angular frequency of a certain RLC series circuit is $\omega$ ₀. A source of sinusoidal emf, with angular frequency $\omega$ , is inserted into the circuit and $\omega$ is varied while the amplitude of the source is held constant. For which of the following values of $\omega$ is the amplitude of the current oscillations the greatest?

A charged capacitor and an inductor are connected in series. At time t = 0 the current is zero, but the capacitor is charged. If T is the period of the resulting oscillations, the next time, after t = 0 that the current is a maximum is:

At time t = 0 the charge on the 50- $\mu$ F capacitor in an LC circuit is 15 $\mu$ C and there is no current. If the inductance is 20 mH the maximum current is:

An RLC series circuit, connected to a source E, is at resonance. Then:

In an RLC series circuit, the source voltage is leading the current at a given frequency f. If f is lowered slightly, then the circuit impedance will:

The impedance of the circuit shown is:

The primary of an ideal transformer has 100 turns and the secondary has 600 turns. Then:

An RLC series circuit has R = 4 $\Omega$ , X_C = 3 $\Omega$ , and X_L = 6 $\Omega$ . The impedance of this circuit is:

The rms value of an ac current is: