Exam 31: Electromagnetic Oscillations and Alternating Current

A 35- $\mu$ F capacitor is connected to an ac source of emf with a frequency of 250 Hz and a maximum emf of 20 V.If the voltage across the capacitor is zero at time t = 0, what is the voltage at time t = 3.0 ms? Assume the phase constant is zero.

An LC circuit has a capacitance of 30 $\mu$ F and an inductance of 15 mH.At time t = 0 the charge on the capacitor is 10 $\mu$ C and the current is 20 mA.The maximum current is:

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

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:

The units of the power factor are:

An LC circuit has an inductance of 15 mH and a capacitance of 10 $\mu$ F.At one instant the charge on the capacitor is 25 $\mu$ C.At that instant the current is changing at the rate:

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 energy stored in the electric field of the capacitor is a maximum is:

An RLC circuit has a resistance of 200 $\Omega$ an inductance of 15 mH, and a capacitance of 34 nF.At time t = 0 the charge on the capacitor is 25 µC and there is no current flowing.After five complete cycles the energy stored in the capacitor is:

A step-down transformer is used to:

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:

The main reason that alternating current replaced direct current for general use is:

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:

An LC circuit has a capacitance of 30 $\mu$ F and an inductance of 15 mH.At time t = 0 the charge on the capacitor is 10 $\mu$ C and the current is 20 mA.The maximum charge on the capacitor is:

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

A series RL circuit is connected to an emf source of angular frequency .The current:

An ac generator producing 10 V (rms)at 200 rad/s is connected in series with a 50- $\Omega$ resistor, a 400-mH inductor, and a 200- $\mu$ F capacitor.The rms voltage across the resistor is:

An ac generator produces 10 V (rms)at 400 rad/s.It is connected to a series RL circuit (R = 17.3 $\Omega$ , L = 0.025 H).The rms current is:

The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLC circuit might due to:

A resistor, an inductor, and a capacitor are connected in parallel to a sinusoidal source of emf.Which of the following is true?

A sinusoidal voltage V(t)has an rms value of 100 V.Its maximum value is: