Exam 31: Electromagnetic Oscillations and Alternating Current

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:

A source with an impedance of 100 $\Omega$ is connected to the primary coil of a transformer and a resistance R is connected to the secondary coil. If the transformer has 500 turns in its primary coil and 100 turns in its secondary coil the greatest power will be dissipated in the resistor if R =:

In an ideal 1:8 step-down transformer, the primary power is 10 kW and the secondary current is 25 A. The primary voltage is:

An RLC series circuit is connected to an oscillator with a maximum emf of = 100 V. If the voltage amplitudes V_R, V_L, and V_C are all equal to each other, then V_R must be:

In a purely capacitive circuit the current:

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

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 magnetic field of the inductor is a maximum is:

An LC circuit has an oscillation frequency of 10⁵ Hz. If C = 0.1 $\mu$ F, then L must be about:

A 150-g block on the end of a spring with a spring constant of 35 N/m is pulled aside 25 cm and released from rest. In the electrical analog the maximum charge on the capacitor is 0.25 C.The maximum current in the LC circuit is:

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:

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

The core of a transformer is made in a laminated form to:

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

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 (in volts) across the capacitor is:

In a purely resistive circuit the current:

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 charge on the capacitor is a maximum is:

The units of the power factor are:

A 150-g block on the end of a spring with a spring constant of 35 N/m is pulled aside 25 cm and released from rest. In the electrical analog the initial charge on the capacitor is:

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

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