Exam 31: Electromagnetic Oscillations and Alternating Current

A power transmission line carries 400A of current at a voltage of 765 kV.If the line has a resistance of 29 µΩ/m, what is the rate at which energy is being dissipated in 800 km of line?

We desire to make an LC circuit that oscillates at 100 Hz using an inductance of 2.5 H.We also need a capacitance of:

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

A capacitor in an LC oscillator has a maximum potential difference of 15 V and a maximum energy of 360 $\mu$ J.At a certain instant the energy in the capacitor is 40 $\mu$ J.At that instant what is the potential difference across the capacitor?

Radio receivers are usually tuned by adjusting the capacitor of an LC circuit.If C = C₁ for a frequency of 600 kHz, then for a frequency of 1200 kHz one must adjust C to:

An LC circuit has an inductance of 20 mH and a capacitance of 5.0 $\mu$ F.At time t = 0 the charge on the capacitor is 3.0 $\mu$ C and the current is 7.0 mA.The total energy is:

In an RLC series circuit, which is connected to a source of emf _mcos( t), the current lags the voltage by 45 ° if:

An RLC circuit has a resistance of 200 $\Omega$ and an inductance of 15 mH.Its oscillation frequency is 7000 Hz.At time t = 0 the current is 25 mA and there is no charge on the capacitor.After five complete cycles the current is:

In an oscillating LC circuit, the total stored energy is U and the maximum charge on the capacitor is Q.When the charge on the capacitor is Q/2, the energy stored in the inductor is:

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 voltage across the inductor is a maximum is:

In an oscillating LC circuit, the total stored energy is U.The maximum energy stored in the capacitor during one cycle is:

An LC circuit has an inductance of 20 mH and a capacitance of 5.0 $\mu$ F.If the charge amplitude is 40 $\mu$ C, what is the current amplitude?

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

The impedance of the circuit shown is:

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

In the diagram, the function y(t)= y_msin( t)is plotted as a solid curve.The other three curves have the form y(t)= y_msin( 11ef00c7_c7b5_b1d5_bc85_a1b64fc96bad_TB6585_11 t + ), where 11ef00c7_84d4_43e4_bc85_0f6454907e9b_TB6585_11 is between - $\pi$ /2 and + $\pi$ /2.Rank the curves according to the value of 11ef00c7_84d4_43e4_bc85_0f6454907e9b_TB6585_11 , from the most negative to the most positive.

The impedance of an RLC series circuit is definitely increased if:

The rms value of an ac current is:

A series circuit consists of a 15- $\Omega$ resistor, a 25-mH inductor, and a 35- $\Omega$ capacitor.If the frequency is 100 Hz the power factor is:

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: