Chapter 28—Direct-Current Circuits

MULTIPLE CHOICE

	1.	At what rate is thermal energy being generated in the 2R-resistor when e = 12 V and R = 3.0 W?

a.	12 W	
b.	24 W	
c.	6.0 W	
d.	3.0 W	
e.	1.5 W	

ANS:	C	PTS:	2	DIF:	Average

	2.	At what rate is thermal energy generated in the 30-W resistor?

a.	20 W	
b.	27 W	
c.	60 W	
d.	13 W	
e.	30 W	

ANS:	D	PTS:	2	DIF:	Average

	3.	What is the magnitude of the potential difference across the 20-W resistor?

a.	3.2 V	
b.	7.8 V	
c.	11 V	
d.	5.0 V	
e.	8.6 V	

ANS:	B	PTS:	2	DIF:	Average

	4.	What is the current in the 10-W resistor ?

a.	0.60 A	
b.	3.0 A	
c.	1.2 A	
d.	2.4 A	
e.	0.30 A	

ANS:	A	PTS:	2	DIF:	Average

	5.	At what rate is thermal energy generated in the 20-W resistor when e = 20 V?

a.	6.5 W	
b.	1.6 W	
c.	15 W	
d.	26 W	
e.	5.7 W	

ANS:	B	PTS:	2	DIF:	Average

	6.	At what rate is thermal energy generated in the 5-W resistor when e = 24 V?

a.	13 W	
b.	3.2 W	
c.	23 W	
d.	39 W	
e.	51 W	

ANS:	B	PTS:	2	DIF:	Average

	7.	When a 20-V emf is placed across two resistors in series, a current of 2.0 A is present in each of the resistors. When the same emf is placed across the same two resistors in parallel, the current through the emf is 10 A. What is the magnitude of the greater of the two resistances?
a.	7.2 W	
b.	7.6 W	
c.	6.9 W	
d.	8.0 W	
e.	2.8 W	

ANS:	A	PTS:	3	DIF:	Challenging

	8.	A resistor of unknown resistance and a 15-W resistor are connected across a 20-V emf in such a way that a 2.0 A current is observed in the emf. What is the value of the unknown resistance?
a.	75 W	
b.	12 W	
c.	7.5 W	
d.	30 W	
e.	5.0 W	

ANS:	D	PTS:	2	DIF:	Average

	9.	What is the current in the 15-W resistor when e = 9.0 V?

a.	0.20 A	
b.	0.30 A	
c.	0.10 A	
d.	0.26 A	
e.	0.60 A	

ANS:	A	PTS:	2	DIF:	Average

	10.	How much heat is produced in the 10-W resistor in 5.0 s when e = 18 V?

a.	72 J	
b.	32 J	
c.	50 J	
d.	18 J	
e.	90 J	

ANS:	D	PTS:	2	DIF:	Average

	11.	Determine e when I = 0.50 A and R = 12 W.

a.	12 V	
b.	24 V	
c.	30 V	
d.	15 V	
e.	6.0 V	

ANS:	B	PTS:	2	DIF:	Average

	12.	Determine R when I = 0.20 A and e = 18 V.

a.	50 W	
b.	8.0 W	
c.	10 W	
d.	20 W	
e.	30 W	

ANS:	D	PTS:	2	DIF:	Average

	13.	Determine the current in the 10-V emf.

a.	2.3 A	
b.	2.7 A	
c.	1.3 A	
d.	0.30 A	
e.	2.5 A	

ANS:	A	PTS:	3	DIF:	Challenging

	14.	What is the magnitude of the current in the 20-W resistor?

a.	0.75 A	
b.	0.00 A	
c.	0.25 A	
d.	0.50 A	
e.	1.00 A	

ANS:	D	PTS:	3	DIF:	Challenging

	15.	Determine the potential difference Va - Vb shown in the circuit below.

a.	-5.0 V	
b.	+5.0 V	
c.	-10 V	
d.	+10 V	
e.	0 V	

ANS:	B	PTS:	3	DIF:	Challenging

	16.	What is the potential difference Vb - Va shown in the circuit below.

a.	-8.0 V	
b.	+8.0 V	
c.	-18 V	
d.	+18 V	
e.	-12 V	

ANS:	A	PTS:	3	DIF:	Challenging

	17.	At what rate is power supplied by the 10-V emf shown below?

a.	-10 W	
b.	+10 W	
c.	zero	
d.	+20 W	
e.	-20 W	

ANS:	B	PTS:	3	DIF:	Challenging

	18.	If e = 8.0 V, at what rate is that emf providing energy to the circuit shown below?

a.	8.4 W	
b.	7.6 W	
c.	5.6 W	
d.	11 W	
e.	2.0 W	

ANS:	C	PTS:	3	DIF:	Challenging

	19.	Determine the magnitude and sense (direction) of the current in the 500-W resistor when I = 30 mA.

a.	56 mA left to right	
b.	56 mA right to left	
c.	48 mA left to right	
d.	48 mA right to left	
e.	26 mA left to right	

ANS:	A	PTS:	2	DIF:	Average

	20.	Determine the magnitude and sense (direction) of the current in the 10-W resistor when I = 1.8 A.

a.	1.6 A right to left	
b.	1.6 A left to right	
c.	1.2 A right to left	
d.	1.2 A left to right	
e.	1.8 A left to right	

ANS:	A	PTS:	2	DIF:	Average

	21.	Determine the resistance R when I = 1.5 A.

a.	40 W	
b.	8.0 W	
c.	85 W	
d.	28 W	
e.	32 W	

ANS:	B	PTS:	2	DIF:	Average

	22.	What is the potential difference VB - VA when the I = 1.5 A in the circuit segment below?

a.	+22 V	
b.	-22 V	
c.	-38 V	
d.	+38 V	
e.	+2.0 V	

ANS:	B	PTS:	2	DIF:	Average

	23.	What is the potential difference VB - VA when I = 0.50 A in the circuit segment shown below?

a.	+28 V	
b.	+2.0 V	
c.	-28 V	
d.	-2.0 V	
e.	+18 V	

ANS:	A	PTS:	2	DIF:	Average

	24.	If R = 2.0 kW, C = 4.0 mF, e = 8.0 V, Q = 20 mC, and I = 3.0 mA, what is the potential difference Vb - Va?

a.	+7.0 V	
b.	+19 V	
c.	+9.0 V	
d.	-3.0 V	
e.	-14 V	

ANS:	C	PTS:	2	DIF:	Average

	25.	If R = 3.0 kW, C = 5.0 mF, e = 6.0 V, Q = 15 mC, and I = 4.0 mA, what is the potential difference Vb - Va?

a.	-3.0 V	
b.	+9.0 V	
c.	-15 V	
d.	+21 V	
e.	-6.0 V	

ANS:	A	PTS:	2	DIF:	Average

	26.	If R = 4.0 kW, C = 3.0 mF, e = 15 V, Q = 12 mC, and I = 2.0 mA, what is the potential difference Vb - Va?

a.	+3.0 V	
b.	-19 V	
c.	-3.0 V	
d.	+27 V	
e.	+21 V	

ANS:	C	PTS:	2	DIF:	Average

	27.	If R = 3.0 kW, C = 6.0 nF, e 1 = 10.0 V, Q = 18 nC, e 2 = 6.0 V, and I = 5.0 mA, what is the potential difference Vb - Va?

a.	-13 V	
b.	+28 V	
c.	+13 V	
d.	-28 V	
e.	+2.0 V	

ANS:	D	PTS:	2	DIF:	Average

	28.	If e 1 = 4.0 V, e 2 = 12.0 V, R1 = 4 W, R2 = 12 W, C = 3 mF, Q = 18 mC, and I = 2.5 A, what is the potential difference Va - Vb?

a.	-30 V	
b.	30 V	
c.	5.0 V	
d.	-5.0 V	
e.	-1.0 V	

ANS:	A	PTS:	2	DIF:	Average

	29.	If the current in the 4.0-W resistor is 1.4 A, what is the magnitude of the potential difference, VA - VB?

a.	69 V	
b.	55 V	
c.	62 V	
d.	48 V	
e.	31 V	

ANS:	D	PTS:	3	DIF:	Challenging

	30.	If I = 0.40 A in the circuit segment shown below, what is the potential difference Va - Vb?

a.	31 V	
b.	28 V	
c.	25 V	
d.	34 V	
e.	10 V	

ANS:	C	PTS:	2	DIF:	Average

	31.	If I = 2.0 A in the circuit segment shown below, what is the potential difference VB - VA?

a.	+10 V	
b.	-20 V	
c.	-10 V	
d.	+20 V	
e.	+30 V	

ANS:	C	PTS:	2	DIF:	Average

	32.	Determine the potential difference, VA - VB, in the circuit segment shown below when I = 2.0 mA and Q = 50 mC.

a.	-40 V	
b.	+40 V	
c.	+20 V	
d.	-20 V	
e.	-10 V	

ANS:	D	PTS:	2	DIF:	Average

	33.	If Q = 400 mC and the potential difference VA - VB = -10 V in the circuit segment shown below, what is the current in the resistor?

a.	1.0 mA right to left	
b.	1.0 mA left to right	
c.	3.5 mA right to left	
d.	3.5 mA left to right	
e.	None of the above	

ANS:	A	PTS:	2	DIF:	Average

	34.	If Q = 350 mC and I = 4.0 mA in the circuit segment shown below, determine the potential difference, VA - VB.

a.	-30 V	
b.	+80 V	
c.	+40 V	
d.	-40 V	
e.	+10 V	

ANS:	D	PTS:	2	DIF:	Average

	35.	In an RC circuit, how many time constants must elapse if an initially uncharged capacitor is to reach 80% of its final potential difference?
a.	2.2	
b.	1.9	
c.	1.6	
d.	3.0	
e.	5.0	

ANS:	C	PTS:	2	DIF:	Average

	36.	How many time constants must elapse if an initially charged capacitor is to discharge 55% of its stored energy through a resistor?
a.	0.60	
b.	0.46	
c.	0.52	
d.	0.40	
e.	1.1	

ANS:	D	PTS:	3	DIF:	Challenging

	37.	In an RC circuit, what fraction of the final energy is stored in an initially uncharged capacitor after it has been charging for 3.0 time constants?
a.	0.84	
b.	0.90	
c.	0.75	
d.	0.60	
e.	0.03	

ANS:	B	PTS:	2	DIF:	Average

	38.	How long will it take a charged 80-mF capacitor to lose 20% of its initial energy when it is allowed to discharge through a 45-W resistor?
a.	0.92 ms	
b.	0.64 ms	
c.	0.40 ms	
d.	0.19 ms	
e.	0.80 ms	

ANS:	C	PTS:	3	DIF:	Challenging

	39.	At t = 0 the switch S is closed with the capacitor uncharged. If C = 50 mF, e = 20 V, and R = 4.0 kW, what is the charge on the capacitor when I = 2.0 mA?

a.	360 mC	
b.	480 mC	
c.	240 mC	
d.	600 mC	
e.	400 mC	

ANS:	D	PTS:	3	DIF:	Challenging

	40.	At t = 0 the switch S is closed with the capacitor uncharged. If C = 30 mF, e = 30 V, and R = 5.0 kW, at what rate is energy being stored in the capacitor when I = 2.0 mA?

a.	32 mW	
b.	40 mW	
c.	44 mW	
d.	36 mW	
e.	80 mW	

ANS:	B	PTS:	2	DIF:	Average

	41.	At t = 0 the switch S is closed with the capacitor uncharged. If C = 40 mF, e = 50 V, and R = 5.0 kW, how much energy is stored by the capacitor when I = 2.0 mA?

a.	20 mJ	
b.	28 mJ	
c.	32 mJ	
d.	36 mJ	
e.	40 mJ	

ANS:	C	PTS:	2	DIF:	Average

	42.	At t = 0 the switch S is closed with the capacitor uncharged. If C = 30 mF, e = 50 V, and R = 10 kW, what is the potential difference across the capacitor when I = 2.0 mA?

a.	20 V	
b.	15 V	
c.	25 V	
d.	30 V	
e.	45 V	

ANS:	D	PTS:	2	DIF:	Average

	43.	A capacitor in a single-loop RC circuit is charged to 85% of its final potential difference in 2.4 s. What is the time constant for this circuit?
a.	1.5 s	
b.	1.3 s	
c.	1.7 s	
d.	1.9 s	
e.	2.9 s	

ANS:	B	PTS:	2	DIF:	Average

	44.	What is the equivalent resistance between points a and b when R = 13 W?

a.	29 W	
b.	23 W	
c.	26 W	
d.	20 W	
e.	4.6 W	

ANS:	D	PTS:	2	DIF:	Average

	45.	What is the equivalent resistance between points a and b when R = 30 W?

a.	27 W	
b.	21 W	
c.	24 W	
d.	18 W	
e.	7.5 W	

ANS:	D	PTS:	2	DIF:	Average

	46.	What is the equivalent resistance between points a and b when R = 12 W?

a.	20 W	
b.	16 W	
c.	24 W	
d.	28 W	
e.	6.0 W	

ANS:	B	PTS:	2	DIF:	Average

	47.	What is the equivalent resistance between points a and b?

a.	14 W	
b.	8.0 W	
c.	6.0 W	
d.	25 W	
e.	40 W	

ANS:	D	PTS:	2	DIF:	Average

	48.	If R1 = 10 W, R2 = 15 W, R3 = 20 W, and I = 0.50 A, at what rate is heat being generated in these resistors?

a.	29 W	
b.	16 W	
c.	22 W	
d.	11 W	
e.	1.1 W	

ANS:	D	PTS:	2	DIF:	Average

	49.	If R1 = 3.0 W, R2 = 6.0 W, R3 = 12 W, and I = 0.50 A, at what rate is heat being generated in R1?

a.	20 W	
b.	17 W	
c.	12 W	
d.	31 W	
e.	6.0 W	

ANS:	C	PTS:	2	DIF:	Average

	50.	A certain brand of hot dog cooker applies a potential difference (120 V) to opposite ends of the hot dog and cooks by means of the joule heat produced. If 60 kJ is needed to cook each hot dog, what current is needed to cook four hot dogs simultaneously in 3.0 min?
a.	11 A	
b.	2.8 A	
c.	8.3 A	
d.	2.1 A	
e.	3.6 A	

ANS:	A	PTS:	2	DIF:	Average

	51.	If 480 C pass through a 4.0-W resistor in 10 min, what is the potential difference across the resistor?
a.	3.6 V	
b.	2.8 V	
c.	2.4 V	
d.	3.2 V	
e.	5.0 V	

ANS:	D	PTS:	2	DIF:	Average

	52.	A 10-V battery is connected to a 15-W resistor and an unknown resistor R, as shown. The current in the circuit is 0.40 A. How much heat is produced in the 15-W resistor in 2.0 min?

a.	0.40 kJ	
b.	0.19 kJ	
c.	0.29 kJ	
d.	0.72 kJ	
e.	0.80 kJ	

ANS:	C	PTS:	2	DIF:	Average

	53.	What is the equivalent resistance between points A and B in the figure when R = 20 W?

a.	77 W	
b.	63 W	
c.	70 W	
d.	84 W	
e.	140 W	

ANS:	C	PTS:	2	DIF:	Average

	54.	What is the equivalent resistance between points A and B in the figure when R = 18 W?

a.	48 W	
b.	64 W	
c.	80 W	
d.	96 W	
e.	110 W	

ANS:	D	PTS:	2	DIF:	Average

	55.	What is the equivalent resistance between points A and B in the figure when R = 10 W?

a.	20 W	
b.	10 W	
c.	25 W	
d.	15 W	
e.	3.2 W	

ANS:	B	PTS:	2	DIF:	Average

	56.	In a loop in a closed circuit, the sum of the currents entering a junction equals the sum of the currents leaving a junction because
a.	the potential of the nearest battery is the potential at the junction.	
b.	there are no transformations of energy from one type to another in a circuit loop.	
c.	capacitors tend to maintain current through them at a constant value.	
d.	current is used up after it leaves a junction.	
e.	charge is neither created nor destroyed at a junction.	

ANS:	E	PTS:	1	DIF:	Easy

	57.	When a capacitor is fully charged, the current through the capacitor in a direct-current circuit is
a.	zero.	
b.	at its maximum value.	
c.	equal to the current in a resistive circuit in parallel with the capacitor circuit.	
d.	greater than the current in a resistor that is farther from the battery than the capacitor.	
e.	zero if it is the only capacitor, but maximum if there is another capacitor in series with it.	

ANS:	A	PTS:	1	DIF:	Easy

	58.	The algebraic sum of the changes of potential around any closed circuit loop is
a.	zero.	
b.	maximum.	
c.	zero only if there are no sources of emf in the loop.	
d.	maximum if there are no sources of emf in the loop.	
e.	equal to the sum of the currents in the branches of the loop.	

ANS:	A	PTS:	1	DIF:	Easy

	59.	The circuit below contains three 100-W light bulbs. The emf e = 110 V. Which light bulb(s) is(are) brightest?

a.	A	
b.	B	
c.	C	
d.	B and C	
e.	All three are equally bright.	

ANS:	A	PTS:	1	DIF:	Easy

	60.	The circuit below contains three 100-watt light bulbs. The emf e = 110 V. Which light bulb(s) is(are) the brightest?

a.	A	
b.	B	
c.	C	
d.	B and C	
e.	All three are equally bright.	

ANS:	A	PTS:	1	DIF:	Easy

	61.	The circuit below contains three 100-watt light bulbs and a capacitor. The emf e = 110V. The capacitor is fully charged. Which light bulb(s) is(are) dimmest?

a.	A	
b.	B	
c.	C	
d.	A and B	
e.	All three are equally bright (or dim).	

ANS:	C	PTS:	1	DIF:	Easy

	62.	The circuit below contains three 100-W light bulbs and a capacitor. The emf e = 110V. At the instant the switch S is closed, which light bulb is brightest?

a.	A	
b.	B	
c.	C	
d.	A and B	
e.	All three are equally bright.	

ANS:	C	PTS:	1	DIF:	Easy

	63.	The circuit below contains three resistors, A, B, and C, which all have equal resistances. The emf e = 110V. Which resistor generates the most thermal energy after the switch is closed?

a.	A	
b.	B	
c.	C	
d.	A and B	
e.	All three generate equal amounts of thermal energy.	

ANS:	C	PTS:	1	DIF:	Easy

	64.	The diagram shown represents a portion of a wire in a circuit. A current is flowing in the wire in the direction shown. Under the convention that it is positive charge that flows the electric field points in the direction of the current. How can the electric field change direction where the wire bends?

a.	There is an excess of negative charge in the center of the wire.	
b.	There is an excess of positive charge at the bottom end of the wire.	
c.	There is an excess of negative charge at the right end of the upper portion of the wire.	
d.	There is an accumulation of positive charge on the surface, particularly at the bend, such that the sum of electric fields gives the new electric field.	
e.	There is an accumulation of electrical potential as the current traverses the wire: The higher potential in the lower half is the source of the field.	

ANS:	D	PTS:	1	DIF:	Easy

	65.	The circuit below contains three 100-W light bulbs and a capacitor. The emf is 110 V and the capacitor is fully charged. Which light bulb(s) is(are) brightest?

a.	A	
b.	B	
c.	C	
d.	A and B	
e.	A and C	

ANS:	B	PTS:	1	DIF:	Easy

	66.	The circuit below contains 4 100-W light bulbs. The emf is 110 V. Which light bulb(s) is(are) brightest?

a.	A	
b.	B	
c.	C	
d.	D	
e.	C and D	

ANS:	B	PTS:	1	DIF:	Easy

	67.	The circuit below contains 4 100-W light bulbs. The emf is 110 V. Which light bulb(s) is(are) brightest?

a.	A	
b.	B	
c.	C	
d.	D	
e.	C and D	

ANS:	B	PTS:	1	DIF:	Easy

	68.	The circuit below contains 3 100-W light bulbs and a capacitor. The emf is 110 V. Which light bulb(s) is(are) brightest? (Assume the capacitor is fully charged.)

a.	A	
b.	B	
c.	C	
d.	A and B	
e.	All three are equally bright.	

ANS:	D	PTS:	1	DIF:	Easy

	69.	Which of the identical light bulb(s) is(are) brightest when the capacitor has half its maximum charge?

a.	A	
b.	B	
c.	C	
d.	A and B	
e.	All three are equally bright.	

ANS:	B	PTS:	1	DIF:	Easy

	70.	The circuit below contains 5 identical light bulbs. The emf is 110 V. Which light bulb(s) is(are) brightest?

a.	A: The one closest to the positive terminal of the battery.	
b.	A and C: The bulbs closest to the positive terminal of the battery.	
c.	A and B: Because they are closest to the terminals of the battery.	
d.	C and D: Because they receive current from A and B and from E.	
e.	E: Because the potential difference across E is that of the battery.	

ANS:	E	PTS:	1	DIF:	Easy

	71.	The battery is disconnected from a series RC circuit after the capacitor is fully charged and is replaced by an open switch. When the switch is closed,
a.	the current through the resistor is always greater than the current through the capacitor.	
b.	the current through the resistor is always less than the current through the capacitor.	
c.	the current through the resistor is always equal to the current through the capacitor.	
d.	the capacitor does not allow current to pass.	
e.	the current stops in the resistor.	

ANS:	C	PTS:	1	DIF:	Easy

	72.	The capacitors are completely discharged in the circuit shown below.

The two resistors have the same resistance R and the two capacitors have the same capacitance C. After the switch is closed, the current
a.	is greatest in C1.	
b.	is greatest in C2.	
c.	is greatest in R1.	
d.	is greatest in R2.	
e.	is the same in C1, C2, R1 and R2.	

ANS:	E	PTS:	1	DIF:	Easy

	73.	Which two circuits are exactly equivalent?

a.	A and B	
b.	B and C	
c.	C and D	
d.	D and E	
e.	B and E	

ANS:	E	PTS:	1	DIF:	Easy

	74.	A circuit consists of 2N resistors, all of resistance R, connected as shown below. A potential difference V is applied to one end, and the other end is at ground potential. The equivalent resistance of the circuit is

a.	.	
b.	R.	
c.	.	
d.	NR.	
e.	2NR.	

ANS:	C	PTS:	2	DIF:	Average

	75.	A circuit consists of N resistors, all of resistance R, connected as shown below. A potential difference V is applied to the circuit. The equivalent resistance of the circuit is

a.	.	
b.	R.	
c.	.	
d.	NR.	
e.	4NR.	

ANS:	C	PTS:	2	DIF:	Average

	76.	A circuit consists of N resistors, all of resistance R, connected as shown below. A potential difference V is applied to the circuit. The equivalent resistance of the circuit is

a.	.	
b.	.	
c.	R.	
d.	NR.	
e.	2NR.	

ANS:	B	PTS:	1	DIF:	Easy

	77.	The circuit below shows three resistors in parallel. R3 > R2 > R1. The resistors are all made of the same wire with the same diameter but have different lengths. Rank the magnitudes of the electric fields in the resistors from least to greatest.

a.	E3 < E2 < E1.	
b.	E2 < E1 = E3.	
c.	E1 = E2 = E3.	
d.	E1 = E3 < E2.	
e.	E1 < E2 < E3.	

ANS:	A	PTS:	2	DIF:	Average

	78.	The circuit below shows three resistors in series. R3 > R2 > R1. The resistors are all made of the same wire with the same diameter but have different lengths. Rank the magnitudes of the electric fields in the resistors from least to greatest.

a.	E3 < E2 < E1.	
b.	E2 < E1 = E3.	
c.	E1 = E2 = E3.	
d.	E1 = E3 < E2.	
e.	E1 < E2 < E3.	

ANS:	C	PTS:	2	DIF:	Average

	79.	A series circuit consists of a 100 V DC power source, a 100 W resistor, and a variable resistor of resistance R, which varies from 0 to 100 W. The current in the circuit is

a.	directly proportional to R.	
b.	inversely proportional to R.	
c.	directly proportional to (100 W + R).	
d.	inversely proportional to (100 W + R).	
e.	neither directly nor inversely proportional to R or to (100 W + R).	

ANS:	D	PTS:	1	DIF:	Easy

	80.	A parallel circuit consists of a 100 V DC power source, a 100 W resistor, and a variable resistor of resistance R, which varies from 0 to 100 W. The current in the circuit is

a.	directly proportional to R.	
b.	inversely proportional to R.	
c.	directly proportional to (100 W + R).	
d.	inversely proportional to (100 W + R).	
e.	neither directly nor inversely proportional to R or to (100 W + R).	

ANS:	E	PTS:	2	DIF:	Average

	81.	A battery has an internal resistance of 4.0 W. Which of the following load resistors would have the most power delivered to it when connected across the battery?
a.	1.4 W	
b.	2.0 W	
c.	4.0 W	
d.	8.0 W	
e.	16 W	

ANS:	C	PTS:	2	DIF:	Average

PROBLEM

	82.	What is the maximum number of 100-W lightbulbs you can connect in parallel in a 120-V home circuit without tripping the 20-A circuit breaker?

ANS:	
23

PTS:	2	DIF:	Average

	83.	A 5000-W resistor and a 50-mF capacitor are connected in series at t = 0 with a 6-V battery. The capacitor is initially uncharged. What is the current in the circuit at t = 0? At t = 0.5 s? What is the maximum charge stored on the capacitor?

ANS:	
1.2 mA, 0.162 mA, 300 mC

PTS:	3	DIF:	Challenging

	84.	An initially uncharged 10-mF capacitor is charged by a 10-V battery through a resistance R. The capacitor reaches a potential difference of 4 V in a period of 3 s after the charging began. Find the value of R.

ANS:	
587 kW

PTS:	3	DIF:	Challenging