Exam 19: Dc Circuits

A constant uniform magnetic field of $0.50 \mathrm {~T}$ is applied at right angles to the plane of a flat rectangular loop of area $3.0 \times 10 ^ { - 3 } \mathrm {~m} ^ { 2 }$ . If the area of this loop changes steadily from its original value to a new value of $1.6 \times 10 ^ { - 3 } \mathrm {~m} ^ { 2 }$ in $1.6 \mathrm {~s}$ , what is the emf induced in the loop?

For the circuit shown in the figure, $V = 60 \mathrm {~V} , C = 20 \mu \mathrm { F } , R = 0.10 \mathrm { M } \Omega$ , and the battery is ideal. Initially the switch S is open and the capacitor is uncharged. The switch is then closed at time $t =$ $0.00 \mathrm {~s}$ . What is the charge on the capacitor $8.0 \mathrm {~s}$ after closing the switch?

A series ac circuit has voltage supplied to it at a frequency of $25.0 \mathrm { kHz }$ with a phase difference between the current and the voltage of magnitude $0.80 \mathrm { rad }$ . If the circuit has a capacitance of $2.0 \mu \mathrm { F }$ and an inductance of $0.030 \mathrm { H }$ , find the resistance of the circuit.

Three resistors of $12 \Omega , 12 \Omega$ , and $6.0 \Omega$ are connected together, and an ideal $12 - \mathrm { V }$ battery is connected across the combination. What is the current from the battery if they are connected (a) in series or (b) in parallel?

What resistance should be added in series with a $6.0 \mathrm { H }$ inductor to give a circuit with a time constant of $3.0 \mathrm {~ms}$ ?

A 120 - $\mathrm { V }$ rms signal at $60.0 \mathrm {~Hz}$ is applied across a series combination of a $30.0 - \mathrm { mH }$ inductor and a $100 - \Omega$ resistor. What is the rms value of the voltage across the inductor?

A series circuit contains a $1.0 - \mathrm { k } \Omega$ resistor, a $5.0 - \mathrm { mH }$ inductor, and an ideal $25 - \mathrm { V }$ power supply. What is the time constant for the circuit?

If emf of the ideal battery is $V = 4.0 \mathrm {~V}$ , what is the current through $R _ { 6 }$ for the circuit shown in the figure?

What resistance must be put in series with a $30 - \mathrm { mH }$ inductor at $4000 \mathrm {~Hz}$ to have a total impedance of $8.0 \times 10 ^ { 4 } \Omega$ ?

The following three appliances are connected in parallel across an ideal $120 - V$ dc power source: 1200-W toaster, 650-W coffee pot, and 600-W microwave. If all were operated at the same time what total current would they draw from the source?

A $120 - \mathrm { V }$ rms voltage at $60 \mathrm {~Hz}$ is applied across an $R C$ circuit. The rms value of the current in the circuit is $0.60 \mathrm {~A}$ , and it leads the voltage by $60 ^ { \circ }$ . What is the resistance in this circuit?

When an initially uncharged capacitor is charged through a $25 - \mathrm { k } \Omega$ resistor by a $75 - \mathrm { V } \mathrm { dc }$ ideal power source, it takes $0.23 \mathrm {~ms}$ for the capacitor to reach $50 \%$ of its maximum charge? What is the capacitance of this capacitor?

A $1.5 - \mathrm { H }$ inductor is connected in series with a $200 - \Omega$ resistor through an ideal $15 - \mathrm { V }$ dc power supply and an open switch. After closing the, what is the maximum energy that will be contained in the inductor?

As shown in the figure, a coil of wire is placed in the $x y$ -plane, centered on the $z$ -axis. A solenoid is centered on the $z$ -axis and is carrying a steady dc current. Which one of the following actions will not result induce an emf in the coil?

The figure shows a series ac circuit. The inductor has a reactance of $80 \Omega$ and an inductance of 220 $\mathrm { mH }$ . A $30 - \Omega$ resistor and a capacitor whose reactance is $80 \Omega$ are also in the circuit, and the rms current in the circuit is $2.0 \mathrm {~A}$ . What is the capacitance of the capacitor?

As shown in the figure, two solenoids are side by side. The switch S is initially open. When $S$ is suddenly closed, the direction of the induced current through the resistor $R$ is

A15- $\Omega$ resistor is connected in parallel with a $30 - \Omega$ resistor. If this combination is now connected in series with an ideal $9.0 - \mathrm { V }$ battery and a $20 - \Omega$ resistor, what is the current through the $15 - \Omega$ resistor?

As shown in the figure, a straight wire carries a current $I$ into the page. The wire passes through the center of a toroidal coil. If the current $I$ is quickly reduced to zero, the direction of the induced current through the resistor $R$ is

A 9-V battery is hooked up to two resistors in series. One has a resistance of $5 \Omega$ , and the other has resistance of $10 \Omega$ . Several locations along the circuit are marked with letters, as shown in the figure. Through which resistor is energy being dissipated at the higher rate?

A transformer is a device that normally