Exam 31: Electromagnetic Oscillations and Alternating Current

An RLC series circuit has L = 100 mH and C = 1 $\Omega$ F.It is connected to a 1000-Hz source emf, and the voltage is found to lead the current by 75 ° .The value of R 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 charge on the capacitor is a maximum is:

The primary of a 3:1 step-up transformer is connected to a source and the secondary is connected to a resistor R.The power dissipated by R in this situation is P.If R is connected directly to the source it will dissipate a power of:

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

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

An electric motor, under load, has an effective resistance of 30 $\Omega$ and an inductive reactance of 40 $\Omega$ .When powered by a source with a maximum voltage of 420 V, the maximum 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.

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?

The resistance of the primary coil of a well-designed, 1:10 step-down transformer is 1 $\Omega$ .With the secondary circuit open, the primary is connected to a 12 V ac generator.The primary current is:

The reactance of a 35- $\mu$ F capacitor connected to a 400-Hz generator 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:

An LC series circuit with an inductance L and a capacitance C has an oscillation frequency f.If we now take two of those inductors, each with inductance L, and two of the capacitors, each with capacitance C, and wire them all in series to make a new circuit, its oscillation frequency will be:

An LC circuit consists of a 1 $\mu$ F capacitor and a 4 mH inductor.Its oscillation frequency is approximately:

The total energy in an LC circuit is 5.0 *10^-6 J.If L = 25 mH the maximum current is:

A 45-mH inductor 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:

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 inductor is:

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 capacitor is:

A generator supplies 100 V to the primary coil of a transformer.The primary has 50 turns and the secondary has 500 turns.The secondary voltage is:

Which of the following has the greatest effect in decreasing the oscillation frequency of an LC circuit? Using instead:

In a purely resistive circuit the current: