Question 1

The phase angle of a series $R L$ ac circuit with a $20.0 - \mathrm { mH }$ inductor and a certain resistor at $1000 \mathrm {~Hz}$ is $20.0 ^ { \circ }$. What is the resistance in this circuit?

Accepted Answer

A)  $145 \Omega$ 
B)  $245 \Omega$ 
C)  $345 \Omega$ 
D)  $100 \Omega$ 
E)  $200 \Omega$ 
A)  $145 \Omega$ 
B)  $245 \Omega$ 
C)  $345 \Omega$ 
D)  $100 \Omega$ 
E)  $200 \Omega$

Question 2

Four resistors are connected across an ideal dc battery with voltage $V$, as shown in the figure. If the total current in this circuit is $I = 1 \mathrm {~A}$, what is the value of the voltage $V$ ?

Accepted Answer

A)  $10 \mathrm {~V}$ 
B)  $2 \mathrm {~V}$ 
C)  $8 \mathrm {~V}$ 
D)  $6 \mathrm {~V}$ 
E)  $4 \mathrm {~V}$ 
A)  $10 \mathrm {~V}$ 
B)  $2 \mathrm {~V}$ 
C)  $8 \mathrm {~V}$ 
D)  $6 \mathrm {~V}$ 
E)  $4 \mathrm {~V}$

Question 3

A $10 - \Omega$ resistor is in series with a $100 - \mu \mathrm { F }$ capacitor at $120 \mathrm {~Hz}$. What is the phase angle?

Accepted Answer

A)  $- 37 ^ { \circ }$ 
B)  $- 53 ^ { \circ }$ 
C)  $- 82 ^ { \circ }$ 
D)  $- 4.7 ^ { \circ }$ 
E)  $+ 37 ^ { \circ }$ 
A)  $- 37 ^ { \circ }$ 
B)  $- 53 ^ { \circ }$ 
C)  $- 82 ^ { \circ }$ 
D)  $- 4.7 ^ { \circ }$ 
E)  $+ 37 ^ { \circ }$

Question 4

You have three capacitors with capacitances of 4.00 µF, 7.00 µF, and 9.00 µF. What is the
equivalent capacitance if they are connected (a) in series and (b) in parallel?

Accepted Answer

(a) 1.98 µ

Question 5

A pure inductor is connected to an ac power supply. In this circuit, the current

Accepted Answer

A)  leads the voltage by $90 ^ { \circ }$. 
B)  lags the voltage by $90 ^ { \circ }$. 
C)  is in phase with the voltage. 
D)  lags the voltage by $45 ^ { \circ }$. 
E)  leads the voltage by $45 ^ { \circ }$. 
A)  leads the voltage by $90 ^ { \circ }$. 
B)  lags the voltage by $90 ^ { \circ }$. 
C)  is in phase with the voltage. 
D)  lags the voltage by $45 ^ { \circ }$. 
E)  leads the voltage by $45 ^ { \circ }$.

Question 6

A flat coil is wrapped with 200 turns of very thin wire on a square frame with sides $18 \mathrm {~cm}$ long. A uniform magnetic field is applied perpendicular to the plane of the coil. If the field changes uniformly from $0.50 \mathrm {~T}$ to $0.00 \mathrm {~T}$ in $8.0 \mathrm {~s}$, find the emf induced in the coil.

Accepted Answer

A)  $2.1 \mathrm { mV }$ 
B)  $4.1 \mathrm { mV }$ 
C)  $0.41 \mathrm {~V}$ 
D)  $0.21 \mathrm {~V}$ 
A)  $2.1 \mathrm { mV }$ 
B)  $4.1 \mathrm { mV }$ 
C)  $0.41 \mathrm {~V}$ 
D)  $0.21 \mathrm {~V}$

Question 7

What is the magnitude of the potential difference between points $C$ and $D$ for the circuit shown in the figure? The battery is ideal, and all the numbers are accurate to two significant figures.

Accepted Answer

A)  $6.0 \mathrm {~V}$ 
B)  $4.0 \mathrm {~V}$ 
C)  $3.0 \mathrm {~V}$ 
D)  $2.0 \mathrm {~V}$ 
A)  $6.0 \mathrm {~V}$ 
B)  $4.0 \mathrm {~V}$ 
C)  $3.0 \mathrm {~V}$ 
D)  $2.0 \mathrm {~V}$

Question 8

For the circuit shown in the figure, $C = 12 \mu \mathrm { F }$ and $R = 8.5 \mathrm { M } \Omega$. Initially the switch $\mathrm { S }$ is open with the capacitor charged to a voltage of $80 \mathrm {~V}$. The switch is then closed at time $t = 0.00 \mathrm {~s}$. What is the charge on the capacitor, when the current in the circuit is $3.3 \mu \mathrm { A }$ ?

Accepted Answer

A)  $620 \mu \mathrm { C }$ 
B)  $340 \mu \mathrm { C }$ 
C)  $480 \mu \mathrm { C }$ 
D)  $700 \mu \mathrm { C }$
Е) $350 \mu \mathrm { C }$ 
A)  $620 \mu \mathrm { C }$ 
B)  $340 \mu \mathrm { C }$ 
C)  $480 \mu \mathrm { C }$ 
D)  $700 \mu \mathrm { C }$
Е) $350 \mu \mathrm { C }$

Question 9

American power plants usually supply $120 \mathrm {~V}$ ac.
(a) At what frequency is this voltage supplied?
(b) What is the maximum voltage?

Accepted Answer

(a) 60 Hz

Question 10

A system of four capacitors is connected across a $90 - V$ voltage source as shown in the figure.
(a) What is the charge on the $4.0 - \mu \mathrm { F }$ capacitor?
(b) What is the charge on the $2.0 - \mu \mathrm { F }$ capacitor?

Accepted Answer

(a) 120 µC

Question 11

A battery you buy at the store has an internal emf of $3.0 \mathrm {~V}$. If it has an internal resistance of $14.0 \Omega$, what current will this battery put out if it is short-circuited?

Accepted Answer

A)  $0.21 \mathrm {~A}$ 
B)  $4.7 \mathrm {~A}$ 
C)  $42 \mathrm {~A}$ 
D)  $130 \mathrm {~A}$ 
A)  $0.21 \mathrm {~A}$ 
B)  $4.7 \mathrm {~A}$ 
C)  $42 \mathrm {~A}$ 
D)  $130 \mathrm {~A}$

Question 12

You wish to construct a simple ac generator with a maximum output of $12 \mathrm {~V}$ when rotated at $60 \mathrm {~Hz}$. A magnetic field of $0.050 \mathrm {~T}$ is available. If the area of the rotating coil is $100 \mathrm {~cm} ^ { 2 }$, how many turns are needed?

Accepted Answer

The answer of You wish to construct a simple ac...

Question 13

A 4.0- $\Omega$ resistor is connected with a $12 - \Omega$ resistor and this combination is connected across an ideal dc power supply with $V = 6.0 \mathrm {~V}$, as shown in the figure. When a total current $I$ flows from the power supply, what is the current through the $12 - \Omega$ resistor?

Accepted Answer

A)  $2.0 \mathrm {~A}$ 
B)  $3.0 \mathrm {~A}$ 
C)  $1.5 \mathrm {~A}$ 
D)  $0.50 \mathrm {~A}$ 
E)  $2.5 \mathrm {~A}$ 
A)  $2.0 \mathrm {~A}$ 
B)  $3.0 \mathrm {~A}$ 
C)  $1.5 \mathrm {~A}$ 
D)  $0.50 \mathrm {~A}$ 
E)  $2.5 \mathrm {~A}$

Question 14

The current through a $50 - \Omega$ resistor is $I = ( 0.80 \mathrm {~A} ) \sin ( 240 t )$, where $t$ is measured in seconds. How much power on average is dissipated in the resistor?

Accepted Answer

A)  $16 \mathrm {~W}$ 
B)  $45 \mathrm {~W}$ 
C)  $64 \mathrm {~W}$ 
D)  $32 \mathrm {~W}$ 
A)  $16 \mathrm {~W}$ 
B)  $45 \mathrm {~W}$ 
C)  $64 \mathrm {~W}$ 
D)  $32 \mathrm {~W}$

Question 15

A $2.0 - \Omega$ resistor is in series with a parallel combination of $4.0 - \Omega , 6.0 - \Omega$, and $12 - \Omega$ resistors. What is the equivalent resistance of this system?

Accepted Answer

A)  $4.0 \Omega$ 
B)  $1.8 \Omega$ 
C)  $24 \Omega$ 
D)  $2.7 \Omega$ 
A)  $4.0 \Omega$ 
B)  $1.8 \Omega$ 
C)  $24 \Omega$ 
D)  $2.7 \Omega$

Question 16

A $120 - \mathrm { V }$ rms voltage is applied across a $6.0 - \mu \mathrm { F }$ capacitor. If the frequency of the generator is 60 $\mathrm { Hz }$, what is the rms value of the current in the circuit?

Accepted Answer

A)  $0.071 \mathrm {~A}$ 
B)  $0.37 \mathrm {~A}$ 
C)  $0.17 \mathrm {~A}$ 
D)  $0.27 \mathrm {~A}$ 
E)  $0.47 \mathrm {~A}$ 
A)  $0.071 \mathrm {~A}$ 
B)  $0.37 \mathrm {~A}$ 
C)  $0.17 \mathrm {~A}$ 
D)  $0.27 \mathrm {~A}$ 
E)  $0.47 \mathrm {~A}$

Question 17

As shown in the figure, a wire and a $10 - \Omega$ resistor are used to form a circuit in the shape of a square with dimensions $20 \mathrm {~cm}$ by $20 \mathrm {~cm}$. A uniform but non-steady magnetic field is directed into the plane of the circuit. The magnitude of the magnetic field is steadily decreased from $2.70 \mathrm {~T}$ to $0.90 \mathrm {~T}$ in a time interval of $96 \mathrm {~ms}$. What is the induced current in the circuit, and what is its direction through the resistor?

Accepted Answer

A)  $75 \mathrm {~mA}$, from $b$ to $a$ 
B)  $45 \mathrm {~mA}$, from $b$ to $a$ 
C)  $45 \mathrm {~mA}$, from $a$ to $b$ 
D)  $110 \mathrm {~mA}$, from $a$ to $b$ 
E)  $75 \mathrm {~mA}$, from $a$ to $b$ 
A)  $75 \mathrm {~mA}$, from $b$ to $a$ 
B)  $45 \mathrm {~mA}$, from $b$ to $a$ 
C)  $45 \mathrm {~mA}$, from $a$ to $b$ 
D)  $110 \mathrm {~mA}$, from $a$ to $b$ 
E)  $75 \mathrm {~mA}$, from $a$ to $b$

Question 18

A charged capacitor is connected in series with a resistor 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?

Accepted Answer

A)   
B)   
C)   
D)   
E)   . 
A)   
B)   
C)   
D)   
E)   .

Question 19

The capacitive network shown in the figure is assembled with initially uncharged capacitors. Assume that all the quantities in the figure are accurate to two significant figures. The switch $\mathrm { S }$ in the network is kept open throughout. What is the total energy stored in the seven capacitors?

Accepted Answer

A)  $96 \mathrm {~mJ}$ 
B)  $48 \mathrm {~mJ}$ 
C)  $144 \mathrm {~mJ}$ 
D)  $72 \mathrm {~mJ}$ 
E)  $120 \mathrm {~mJ}$ 
A)  $96 \mathrm {~mJ}$ 
B)  $48 \mathrm {~mJ}$ 
C)  $144 \mathrm {~mJ}$ 
D)  $72 \mathrm {~mJ}$ 
E)  $120 \mathrm {~mJ}$

Question 20

A $120 - \mathrm { V }$ rms voltage at $60.0 \mathrm {~Hz}$ is applied across an inductor, capacitor and a $100 - \Omega$ resistor in series. If the maximum value of the current in this circuit is $1.60 \mathrm {~A}$, what is the rms value of the current in this circuit?

Accepted Answer

A)  $1.82 \mathrm {~A}$ 
B)  $2.26 \mathrm {~A}$ 
C)  $1.60 \mathrm {~A}$ 
D)  $1.13 \mathrm {~A}$ 
E)  $2.66 \mathrm {~A}$ 
A)  $1.82 \mathrm {~A}$ 
B)  $2.26 \mathrm {~A}$ 
C)  $1.60 \mathrm {~A}$ 
D)  $1.13 \mathrm {~A}$ 
E)  $2.66 \mathrm {~A}$

Exam 19: Dc Circuits

The phase angle of a series RLR LRL ac circuit with a 20.0−mH20.0 - \mathrm { mH }20.0−mH inductor and a certain resistor at 1000 Hz1000 \mathrm {~Hz}1000 Hz is 20.0∘20.0 ^ { \circ }20.0∘ . What is the resistance in this circuit?

Four resistors are connected across an ideal dc battery with voltage VVV , as shown in the figure. If the total current in this circuit is I=1 AI = 1 \mathrm {~A}I=1 A , what is the value of the voltage VVV ?

A 10−Ω10 - \Omega10−Ω resistor is in series with a 100−μF100 - \mu \mathrm { F }100−μF capacitor at 120 Hz120 \mathrm {~Hz}120 Hz . What is the phase angle?

You have three capacitors with capacitances of 4.00 µF, 7.00 µF, and 9.00 µF. What is the equivalent capacitance if they are connected (a) in series and (b) in parallel?

A pure inductor is connected to an ac power supply. In this circuit, the current

What is the magnitude of the potential difference between points CCC and DDD for the circuit shown in the figure? The battery is ideal, and all the numbers are accurate to two significant figures.

American power plants usually supply 120 V120 \mathrm {~V}120 V ac. (a) At what frequency is this voltage supplied? (b) What is the maximum voltage?

A system of four capacitors is connected across a 90−V90 - V90−V voltage source as shown in the figure. (a) What is the charge on the 4.0−μF4.0 - \mu \mathrm { F }4.0−μF capacitor? (b) What is the charge on the 2.0−μF2.0 - \mu \mathrm { F }2.0−μF capacitor?

A battery you buy at the store has an internal emf of 3.0 V3.0 \mathrm {~V}3.0 V . If it has an internal resistance of 14.0Ω14.0 \Omega14.0Ω , what current will this battery put out if it is short-circuited?

The current through a 50−Ω50 - \Omega50−Ω resistor is I=(0.80 A)sin⁡(240t)I = ( 0.80 \mathrm {~A} ) \sin ( 240 t )I=(0.80 A)sin(240t) , where ttt is measured in seconds. How much power on average is dissipated in the resistor?

A 2.0−Ω2.0 - \Omega2.0−Ω resistor is in series with a parallel combination of 4.0−Ω,6.0−Ω4.0 - \Omega , 6.0 - \Omega4.0−Ω,6.0−Ω , and 12−Ω12 - \Omega12−Ω resistors. What is the equivalent resistance of this system?

A 120−V120 - \mathrm { V }120−V rms voltage is applied across a 6.0−μF6.0 - \mu \mathrm { F }6.0−μF capacitor. If the frequency of the generator is 60 Hz\mathrm { Hz }Hz , what is the rms value of the current in the circuit?

A charged capacitor is connected in series with a resistor 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?

Introduction, Measurement, Estimating

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Filters

The phase angle of a series $R L$ ac circuit with a $20.0 - \mathrm { mH }$ inductor and a certain resistor at $1000 \mathrm {~Hz}$ is $20.0 ^ { \circ }$ . What is the resistance in this circuit?

A $10 - \Omega$ resistor is in series with a $100 - \mu \mathrm { F }$ capacitor at $120 \mathrm {~Hz}$ . What is the phase angle?

What is the magnitude of the potential difference between points $C$ and $D$ for the circuit shown in the figure? The battery is ideal, and all the numbers are accurate to two significant figures.

American power plants usually supply $120 \mathrm {~V}$ ac. (a) At what frequency is this voltage supplied? (b) What is the maximum voltage?

A battery you buy at the store has an internal emf of $3.0 \mathrm {~V}$ . If it has an internal resistance of $14.0 \Omega$ , what current will this battery put out if it is short-circuited?

The current through a $50 - \Omega$ resistor is $I = ( 0.80 \mathrm {~A} ) \sin ( 240 t )$ , where $t$ is measured in seconds. How much power on average is dissipated in the resistor?

A $2.0 - \Omega$ resistor is in series with a parallel combination of $4.0 - \Omega , 6.0 - \Omega$ , and $12 - \Omega$ resistors. What is the equivalent resistance of this system?

A $120 - \mathrm { V }$ rms voltage is applied across a $6.0 - \mu \mathrm { F }$ capacitor. If the frequency of the generator is 60 $\mathrm { Hz }$ , what is the rms value of the current in the circuit?