Exam 19: Dc Circuits

The figure shows a series ac circuit. The inductor has a reactance of $60 \Omega$ and an inductance of 150 $\mathrm { mH }$ . A $50 - \Omega R$ and a capacitor $C$ whose reactance is $90 \Omega$ are also in the circuit, and the rms current in the circuit is $1.5 \mathrm {~A}$ . What is the rms voltage of the source?

At what frequency will the capacitive reactance of a $0.010 - \mu \mathrm { F }$ capacitor be $100 \Omega$ ?

What current flows from the battery in the circuit shown in the figure? The battery is ideal, and all the numbers are accurate to two significant figures.

Which one of the following capacitances in series with a $100 - \Omega$ resistor and $15 - \mathrm { mH }$ coil will give a total impedance of $110 \Omega$ at $2.0 \mathrm { kHz }$ ?

The network shown is assembled with uncharged capacitors $X , Y$ , and $Z$ , with $C X = 8$ .- $\mu F$ , $C _ { Y } = 9 . - \mu F$ and $C _ { Z } = 1.0 \mu F$ . The switches $S _ { 1 }$ and $S _ { 2 }$ are initially open, and a potential difference $V _ { a b } = 120 \mathrm {~V}$ is applied between points $a$ and $b$ . After the network is assembled, switch $\mathrm { S } _ { 1 }$ is then closed, but switch $S _ { 2 }$ is kept open. How much charge is finally stored in capacitor $Y$ ?

A battery has an emf $\varepsilon = 12 \mathrm {~V}$ and an internal resistance $r = 2.0 \Omega$ , as shown in the figure. When a $3.0 - \Omega$ cable is connected across the battery terminals $a$ and $b$ , the rate at which chemical energy in the battery is depleted is closest to

The resistors in the circuit shown in the figure each have a resistance of $700 \Omega$ . What is the equivalent resistance between points $a$ and $b$ of this combination?

A number of resistors are connected across points $A$ and $B$ as shown in the figure. What is the equivalent resistance between points $A$ and $B$ ?

Two resistors in series are equivalent to $9.0 \Omega$ , and in parallel they are equivalent to $2.0 \Omega$ . What are the resistances of these two resistors?

In the circuit shown in the figure, $R _ { 1 } = 10 \Omega , R _ { 2 } = 12 \Omega , R _ { 3 } = 20 \Omega , V _ { 1 } = 1.0 \mathrm {~V} , V _ { 2 } = 7.0 \mathrm {~V}$ , and the batteries are both ideal. What is the current through $R _ { 1 }$ ?

A 25.0-mH inductor, a 2.00- $\mu \mathrm { F }$ capacitor, and a certain resistor are connected in series across an ac voltage source at $1.00 \mathrm { kHz }$ . If the impedance of this circuit is $200 \Omega$ , what is the value of the resistor?

In the figure, a bar magnet moves away from the solenoid. The direction of the induced current through the resistor $R$ is

Two 100-W light bulbs of fixed resistance are to be connected to an ideal 120-V source. What are the current, potential difference, and dissipated power for each bulb when they are connected (a) in parallel (the normal arrangement)? (b) in series?

An ideal solenoid with 3000 turns is $70.0 \mathrm {~cm}$ long. If its self-inductance is $25.0 \mathrm { mH }$ , what is its radius? $\left( \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } \right)$

A combination of a $2.0 - \Omega$ resistor in series with $4.0 - \Omega$ resistor is connected in parallel with a $3.0 - \Omega$ resistor. What is the equivalent resistance of this system?

An uncharged capacitor is connected in series with a resistor, a dc battery, and an open switch. At time t = 0 s, the switch is closed. Which of the graphs below best describes the Charge Q on the capacitor as a function of time t?

The reactance of a capacitor is $4.0 \mathrm { k } \Omega$ at a frequency of $0.60 \mathrm { kHz }$ . What is the capacitance?

The capacitor shown in the circuit in the figure is initially uncharged when the switch $\mathrm { S }$ is suddenly closed, and the battery is ideal. After one time constant has gone by, find (a) the current through the resistor and (b) the charge on the capacitor. Assume that the numbers shown are all accurate to two significant figures.

The primary coil of an ideal transformer has 100 turns and its secondary coil has 400 turns. If the ac voltage applied to the primary coil is $120 \mathrm {~V}$ , what voltage is present in its secondary coil?

The figure shows a series ac circuit. The inductor has a reactance of $50 \Omega$ and an inductance of 220 $\mathrm { mH }$ . An $80 - \Omega$ resistor and a capacitor whose reactance is $160 \Omega$ are also in the circuit, and the rms current in the circuit is $2.2 \mathrm {~A}$ . What is the voltage amplitude across the capacitor?