Exam 31: Electromagnetic Oscillations and Alternating Current

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 emf induced in the inductor?

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:

Consider the mechanical system consisting of two springs and a block, as shown.Which one of the five electrical circuits (I, II, III, IV, V)is the analog of the mechanical system?

In the circuit shown, switch S is first pushed up to charge the capacitor.When S is then pushed down, the current in the circuit will oscillate at a frequency of:

Iron, rather than copper, is used in the core of transformers because iron:

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

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:

In order to maximize the rate at which energy is supplied to a resistive load, the power factor of an RLC circuit should be as close as possible to:

In a series RLC circuit the rms value of the generator emf is and the rms value of the current is i.The current lags the emf by $\phi$ .The average power supplied by the generator is given by:

For a power transmission line, the transmission should be at low current and high voltage because:

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:

In a purely capacitive circuit the current:

In a sinusoidally driven series RLC circuit, the inductive resistance is X_L = 200 $\Omega$ , the capacitive reactance is X_C = 100 $\Omega$ , and the resistance is R = 50 $\Omega$ .The current and applied emf would be in phase if:

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:

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

An RLC series circuit is driven by a sinusoidal emf with angular frequency _d.If 11ef00c9_0386_d8a7_bc85_1b8a7e3174ea_TB6585_11 _d is increased without changing the amplitude of the emf, the current amplitude increases.If L is the inductance, C is the capacitance, and R is the resistance, this means that:

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- $\Omega$ F capacitor.The rms current is:

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?

The rms value of a sinusoidal voltage is , where V₀ is the amplitude.What is the rms value of its fully rectified wave? Recall that V_rect(t)= $\mid$ V(t) $\mid$ .

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: