Exam 31: Electromagnetic Oscillations and Alternating Current

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?

The rms value of an ac current is:

A 45-mH inductor 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 inductor is zero at time t = 0, what is the voltage at time t = 2.0 ms? Assume the phase constant is zero.

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

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:

An RLC circuit has a sinusoidal source of emf. The average rate at which the source supplies energy is 5 nW. This must also be:

The average power supplied to the circuit shown passes through a maximum when which one of the following is increased continuously from a very low to a very high value?