Explain why birds can sit on power lines safely, whereas lean+fo17+ ovvfq9v v8vml ing a metal ladder up agains7fqvvm1o9vvf 8ov l++ t a power line to fetch a stuck kite is extremely dangerous.

Discuss the advantages and disadvantages ofbx;e, jshivi ot** p2v 5c6yq, Christmas tree lights connected in parallel versuoq pv iv,s2jt,65h;ci*y bex*s those connected in series.

If all you have is a 120-V line, would it be possible to light severv6ybq 6awy2 k7al 6-V lamps without burning them out6yak7vwb62 yq? How?

Two lightbulbs of resistance 3*t -cmzod6pye+ygkh,c13h d$R_1$ and $R_2(R_2>R_1)$ are connected in series. Which is brighter? What if they are connected in parallel? Explain.

Household outlets are often double outlets. Arpo+8 h; qcmd/tt2xjc:c/vz7z e these connected in series or parallel? How do you know?oc8cd :hxq2 t;p+cm/7t / jvzz

With two identical lightbulbs and two identical batteries, qoqlf-wo v: u;6fn .cgu,)gt:how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligq fvguwof:)6t- c g;u,q .:lonible internal resistance.)

If two identical resistors are connecterwr bjqp8 (27q hf 2b(o/gke3p 9sho5qd in series to a battery, does the battery have to supply more poqwjgpr(b(5f pq hb2o q78/rh9 2e3skower or less power than when only one of the resistors is connected? Explain.

You have a single 60-W bulb on in your 0w9uq ps(uu 6zroom. How does the overall resistance of your room’s electric circuit ch6uu(p sqz uw09ange when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below), does the sign (or or 8 0hzy 0cxjf.w.z.ndirection) of a battery’s emf depend on the direction of current throuh0 xjocyr80.nzz. w .fgh the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “increases,” “decreai jmakbu7:bv-(3y:ib1yu+n erm mr0 7ses,” or “stays the same” to completej b -maeir r+ 7 1b3uu7iykn::(m0vymb the following statements:
(a) If $R_7$ increases, the potential difference between A and E  ----待选择----stays in samedecreaseincrease . Assume no resistance in Ann meter and power supply.
(b) If $R_7$ increases, the potential difference between A and E  ----待选择----stays in samedecreaseincrease . Assume Ann meter and power supply have resistance.
(c) If $R_7$ increases, the voltage drop across $R_4$  ----待选择----stays in samedecreaseincrease .
(d) If $R_2$ decreases, the current through $R_1$  ----待选择----stays in samedecreaseincrease .
(e) If $R_2$ decreases, the current through $R_6$  ----待选择----stays in samedecreaseincrease .
(f) If $R_2$ decreases, the current through $R_3$  ----待选择----stays in samedecreaseincrease .
(g) If $R_5$ increases, the voltage drop across $R_2$  ----待选择----stays in samedecreaseincrease .
(h) If $R_5$ increases, the voltage drop across $R_4$  ----待选择----stays in samedecreaseincrease .
(i) If $R_2$,$R_5$, and $R_7$ increase, power supply (r = 0)  ----待选择----stays in samedecreaseincrease .

For what use are batteries connected in series? For what use are they co1,;j)gzl n luwnnected in parallel? nugz)j l1lw;, Does it matter if the batteries are nearly identical or not in either case?

Can the terminal voltage276 jf hxg1rm (64r2u ibiren6 ax6ffq of a battery ever exceed its emf? Explain.

Explain in detail how you could measure the i- ohk 4a5y.qvtnternal resistance of a battery.

Compare and discuss the formulas f-lt rx/rau2w. or resistors and for capacitors when connected in series anxr rwa./ul2 -td in parallel.

Suppose that three identical capacitors are connected to a battery.7e93egds nm csp5:)xv Will they store more energy if connected in series or in parallel?9vn 7s)sgcdmx3 :ee5p

Why is it more dangerous to turnnu+-s(mxd6;i o1 5xgan- nb nt on an electric appliance when you are standing outside in ba-i mxsna o;6g b(t+n5 1-xnudnre feet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphone. The cha) , ha9fpv22lemqp*v:arz ql tj-(n-j s9vfk6nging air pressure in a sound wave causes one plate of the capacitor C to move back and forth. Explain how a current of the same frequmv2*vlla6f-j, p-e9h2zr psq)(9na :qvk jt fency as the sound wave is produced.

Design a circuit in which two different switches of the type show6glxpm 1jvz-04w;9zhz s1xj un in (Fig. Below)jvl; -9zw1zjgsz1 u m0x6ph4x can be used to operate the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from the battery until lbyew;t3r3m q5,v. bq the capacitor is completely charged. Is the total energy supplied by the battery equal to the total energy swe 5y qqb,mb3l.rtv ;3tored by the capacitor? If not, where does the extra energy go?

What is the main difference between an analog voltmeter w0rw*r 7zx n*yand an analog ammeter?

What would happen if you mistake79 /6msvte95z* v x:xpr3ro bbdjq wl5nly used an ammeter where you needed to use a voltmet3 9 5lbxjveqtb*wm9 vszxr 5o:rd7 p6/er?

Explain why an ideal ammeter would have zero resistance and an ideal voltm(k nm; 9pfx(taeter infinite m k;anx(9(fptresistance.

A voltmeter connected across a resistor always rv nw:n 0ldy87b0 lfgg8eads less than the actual voltage across d8n7 g0gv ybnw0 fl8:lthe resistor when the meter is not present. Explain.

A small battery-operated flashlight requires a single 1.5-V battery. Theq d46:q k.bqeq bulb is barely glowing, but when you take the battery out and check it with a voltmeter, it regist4dq6 e.qk:q bqers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an i,weuz.cm :-by jv,kl :e3.*li8tpke5 izpfx /nternal resistance of $0.900\Omega$ and an emf of $8.50\,V$ when the battery is connected in series with
(a) an $81.0-\Omega$ resistor,    V
(b) an $810-\Omega$ resistor.    V

  Four $1.5-V$ cells are connected in series to a $12-\Omega$ lightbulb. If the resulting current is $0.45\,A$, what is the internal resistance of each cell, assuming they are identical and neglecting the wires?    $\Omega$

  What is the internal r qy.qi 0)kvbhy60 kzu/ r6u.k*ikwyy e- p8kr:esistance of a $12.0-V$ car battery whose terminal voltage drops to $8.4\,V$
when the starter draws $75\,A$?    $\Omega$
What is the resistance of the starter?    $\Omega$

  A $1.5-V$ dry cell can be tested by connecting it to a low-resistance ammeter. It should be able to supply at least $22\,A$. What is the internal resistance of the cell in this case, assuming it is much greater than that of the ammeter?    $\Omega$

  Four $240-\Omega$ lightbulbs are connected in series.
What is the total resistance of the circuit?    $\Omega$
What is their resistance if they are connected in parallel?    $\Omega$

  Three $45-\Omega$ lightbulbs and three $75-\Omega$ lightbulbs are connected in series.
(a) What is the total resistance of the circuit?    $\Omega$
(b) What is their resistance if all six are wired in parallel?    $\Omega$

  A $650-\Omega$ and a $2200-\Omega$ resistor are connected in series with a $12-V$ battery. What is the voltage across the $2200-\Omega$ resistor?    V

  Given only one $25-\Omega$ and one $35-\Omega$ resistor, list all possible values of resistance that can be obtained.    $\Omega$    $\Omega$    $\Omega$    $\Omega$

  Suppose that you haveqhui rx;/e.91 rsdoe3x j,s:p a $680-\Omega$, a $940-\Omega$ and a $1.20-k\Omega$ resistor. What is
(a) the maximum,    $\Omega$
(b) the minimum resistance you can obtain by combining these?    $\Omega$

Suppose that you have aidykaqhf .)gey;y-bt cx/1 0, $6.0-V$ battery and you wish to apply a voltage of only $4.0\,V$. Given an unlimited supply of $1.0-\Omega$ resistors, how could you connect them so as to make a “voltage divider” that produces a $4.0-V$ output for a $6.0-V$ input?

  Three $240-\Omega$ resistors can be connected together in four different ways, making combinations of series and/or parallel circuits. What are these four ways, and what is the net resistance in each case?
The resistors can all be connected in series   $\Omega$
The resistors can all be connected in parallel.   $\Omega$
Two resistors in series can be placed in parallel with the third.   $\Omega$
Two resistors in parallel can be placed in series with the third.    $\Omega$

  A battery with an emf of 6gope s1ofo9m.g ;c;x$12.0\,V$ shows a terminal voltage of $11.8\,V$ when operating in a circuit with two lightbulbs rated at $3.0\,W$ (at $12.0\,V$) which are connected in parallel. What is the battery’s internal resistance?    $\Omega$

  Eight identical lights are connected in series across bsheou:w1 d :(y1+ agma $110-V$ line.
(a) What is the voltage across each bulb? V$\approx$    V(Round to the nearest integer)
(b) If the current is $0.50\,A$, what is the resistance of each bulb, and what is the power dissipated in each?
R $\approx$    $\Omega$(Round to the nearest integer)
P $\approx$    W(retain one decimal places)

  Eight lights are connected in parallepv6k85wl3gzzq g:z x 8l to a $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?
$V_R $ =    $\Omega$
firaction wasted =   

  Eight $7.0-W$ Christmas tree lights are connected in series to each other and to a $110-V$ source. What is the resistance of each bulb?    $ \Omega$

  A close inspection of an elec6-xhjybp 8o/t z4y -2x .fuwmstric circuit reveals that a $480-\Omega$ resistor was inadvertently soldered in the place where a $320-\Omega$ resistor is needed. How can this be fixed without removing anything from the existing circuit?    $\Omega$

  Determine
(a) the equivalent resistance of the circuit shown in (Fig. Below),
$R_{eq}$ =   $\Omega$
$V_{470}$ =    V
(b) the voltage across each resistor. $V_{parallel}$    V

  A $75-W$, $110-V$ bulb is connected in parallel with a 40-W, 110-V bulb. What is the net resistance?    $\Omega$(Round to the nearest integer)

  Consider the network of resistors shown in (Fig. gf*iz q4bklvos*xv 3v9p,t /d*dt .1y Below). Answer qualitatively: 1,x9 k.l t/ s **zpvvb4todyi3gd*qvf
(a) What happens to the voltage across each resistor when the switch S is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(b) What happens to the current through each when the switch is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(c) What happens to the power output of the battery when the switch is closed?  ----待选择----increasedecrease 
(d) Let $R_1=R_2=R_3=R_4=125\Omega$ and $V\,=\,22.0\,V$. Determine the current through each resistor before and after closing the switch. Are your qualitative predictions confirmed? Notice that the current through each of the parallel resistors is half of the total current, within the limits of significant figures. $I_1$ =    A $I_3$ =    A $I_4$    A Notice that the current through each of the parallel resistors is one third of the total current, within the limits of significant figures.$I_1$ =    A $I_2$ =    A $I_3$ =    A $I_4$ =    A  ----待选择----YesNo 

  What is the net resistance of the circuit connected to the battery in (Fig. Bel.jxzt xf5u.; c:jn4sfox4jj:s u ;c. ffx.tz5nw)? Each resistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a bawxy 2:u7y. llkih* r0uttery as shown in (Fig. Below). Qualitatively, what happens tw.:iyulxkr *2h7 0y luo
(a) the voltage drop across each of these resistors, $V_{left}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0 
(b) the current flow through each, $I_{left}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0 
(c) the terminal voltage of the battery, when the switch S is opened, after having been closed for a long time? terminal voltage  ----待选择----decreaseincrease0 
(d) If the emf of the battery is 15.0 V, what is its terminal voltage when the switch is closed if the internal resistance is $0.50\Omega$ and $R\,=\,5.5\Omega$?
$V_{terminal\,closed}$ =    V
(e) What is the terminal voltage when the switch is open? $V_{terminal\,closed}$ =    V

  A $2.8-k\Omega$ and a $2.1-k\Omega$ resistor are connected in parallel; this combination is connected in series with a $1.8-k\Omega$ resistor. If each resistor is rated at $\frac{1}{2}W$ (maximum without overheating), what is the maximum voltage that can be applied across the whole network?    V

  Calculate the current in the circuit of (Fig.bc , 76uyst.qp c3nya0 Below) and show that the sum of all the 3cut,by y70 pcn6 s.qavoltage changes around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal vowd6fy ( ln3he0ltage of each battery in (Fig. Below). 18V battery =    V 12V battery =    V

  (a) What is the potential diffeg0ufc. , fwn2krence between points a and d in (Fig. Below a) (samek.ff g wu,c0n2 circuit as Fig. Below b, ), $V_{ad}$    V
(b) what is the terminal voltage of each battery?
80V battery =    V
45V battery =    V

a
b

  For the circuit shown in (Fig. Below), find thee) a;y t/0hthgy((tno potential difference between points a and b. Each resistor(an(oyh;yhte 0gt )t/ has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the currenu9: c)/ dykyzy0 ffw8mts through $R_1$ and $R_2$ in (Fig. Below). $I_1$    A  ----待选择----leftright  $I_2$    A  ----待选择----leftright 

  Repeat Problem 27, now assuming thahb*g a4++;n vfd n0qpat each battery has an internal resistance $r\,=\,1.2\Omega$.
$I_1$ $\approx$    A  ----待选择----leftright (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftright  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftright  (retain two decimal places)

  Determine the magnitudes and directions of tu2xq r*/ tnl2whe currents in each resistor shown in (Fig. 2*/2 ntqrwxulBelow). The batteries have emfs of $E_1\,=\,9.0V$ and $E_2\,=\,12.0V$ and the resistors have values of $R_1\,=\,25\Omega$,$R_2\,=\,18\Omega$, and $R_3\,=\,35\Omega$
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Repeat Problem 29, assuming each battery h6y ze;.bx 8uiwas internal resistance $r\,=\,1.0\Omega$.
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Calculate the currents in ea +jujfx 9tc69w l45 hpxd.(tks hhiqdaj 6u+3:ch resistor of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curren(nyfz-iz eibi+ *gak0+ 3c)eb3 hehu -ts $I_1$,$I_2$, and $I_3$ in (Fig. Below). Assume the internal resistance of each battery is $r\,=\,1.0\Omega$$I_1$ $\approx$    A(retain two decimal places)
$I_2$ $\approx$    A (retain two decimal places)
$I_3$ $\approx$    A (retain three decimal places)
(b) What is the terminal voltage of the 6.0-V battery? $V_{terminal}$    V

  What would the curren7j t0 55m4:d9eyhuo kd .i expu+jw vayv*sf61t $I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, with unequal emfsdm+5,10;dy og cpbdw j of 2.00 V and 3.00 V, are connected as showm ;pb d,y1gj +w5ddco0n in (Fig. Below). If each internal resistance is $r\,=\,0.100\Omega$ and $R\,=\,4.00\Omega$, what is the voltage across the resistor R? $V_R$ $\approx$    V (retain two decimal places)

  (a) Six $4.7-\mu F$ capacitors are connected in parallel. What is the equivalent capacitance? $C_{eq}$ =    $\mu F$
(b) What is their equivalent capacitance if connected in series? $C_{eq}$ =    $\mu F$

  You have three capacitors, 07pheqe,bctuh .l7 w)of capacitance 3200 pF, 7500 pF, and $0.0100\mu F$ . What maximum and minimum capacitance can you form from these? How do you make the connection in each case?
$C_{max}$ =    $ \times10^{-8 }\;F$ in  ----待选择----parallelseries 
$C_{min}$ =    $ \times10^{-9 }\;F$ in  ----待选择----parallelseries 

  A $3.00-\mu F$ and a $4.00-\mu F$ capacitor are connected in series, and this combination is connected in parallel with a $2.00-\mu F$ capacitor (see Fig. Below). What is the net capacitance? $C_{eq}$ =    $\mu F$

  If 26.0 V is applied across the yi81a3r cm3j soq/kt3whole network of (Fig. Below), calculate the voltage across each cayj3at3coi mr38 1k/qspacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of a circuit is to be reduced 1yisop n() dm/from 4800 pF to 2900 pF. (p dn/) omisy1
What capacitance can be added to the circuit to produce this effect without removing existing circuit elements?    $ \times10^{ -9}\;F$
Must any existing connections be broken in the process?  ----待选择----YesNo 

  An electric circuit was accidentally ( 1f:4czt 0/*yu kfi wsueg(vyconstructed using a $5.0-\mu F$ capacitor instead of the required $16-\mu F$ value. Without removing the $5.0-\mu F$ capacitor, what can a technician add to correct this circuit?
   $\mu F$
conneected in  ----待选择----parallelseries 

Determine the equivalent capacitance of the circuit lhaig-b9 a ap 1dzh88l:do,10/b4h6x ipa a uvshown in (Fig. Below).

  In (Fig. Below), if z- ka )-pqmra /j0ltue3sx.e:$C_1=C_2=2C_3=22.6\mu F$, how much charge is stored on each capacitor when $V\,=\,45.0V$?
$Q_1$   $ \times10^{-3 }\;C$
$Q_2$   $ \times10^{-4 }\;C$
$Q_3$   $ \times10^{-4 }\;C$

  In (Fig. Below), sup 5ge,bk ;6sdmtpose $C_1=C_2=2C_3=16.0\mu F$, If the charge on $C_2$ is $Q_2\,=\,24.0\,\mu C$, determine the charge on each of the other capacitors, the voltage across each capacitor, and the voltage V across the entire combination.
$ Q_{1}$ =    $\mu C$, $V_{1}$=   V
$ Q_{2}$ =    $\mu C$, $ V_{2}$=    V
$ Q_{3}$ =   $\mu C$, $ V_{3}$=    V
V=    V

  In (Fig. Below), let )2vn h4u nqf(o$V\,=\,78V$ and $C_1=C_2=2C_3=7.2\mu F$. How much energy is stored in the capacitor network?    $ \times10^{-2 }\;J$

  A $0.40-\mu F$ and a $0.60-\mu F$ capacitor are connected in series to a 9.0-V battery. Calculate
(a) the potential difference across each capacitor,
$V_1$ =    V
$V_2$ =    V
(b) the charge on each. $Q_1$ =    $ \times10^{-6 }\;C$
(c) Repeat parts (a) and (b) assuming the two capacitors are in parallel.
$V_1$ =    V
$V_2$ =    V
$Q_1$ =    $ \times10^{-6 }\;C$
$Q_2$ =    $ \times10^{-6 }\;C$

Three conducting plates, each of area A, are connected as shoy7c1sub q e0fhl x8)g*wn in (Fig. Below).)x g*8e sfqyhc ul71b0
(a) Are the two capacitors formed connected in series or in parallel?
(b) Determine C as a function of $d_1$,$d_2$, and A. Assume $d_1+d_2$ is much less than the dimensions of the plates.

  A circuit contains a d8h 4(gndnwq hw*.85 os k*mfhsingle 250-pF capacitor hooked across a battery. It is desired to store three times as much energy in a combid 4o(w m8whfgk8.n5 dn qh**hsnation of two capacitors by adding a single capacitor to this one.
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is connecteduj 9vlu.;w(qsup 1 uqcuy- c:vn,j7z 0 in series with an unknown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its pucvzyp jv ;9u10sq7 unju. -:l,uw(qclates, what is the unknown capacitance?    pF

  Electrocardiographs lw*t v(2x rar5 c+o5v-sjg2jhare often connected as shown in (Fig. Below). The leads are said to be capacitively coupled. A time constant of 3.0-j sh v2o5cvt 5 +(grx2jwl*ar s is typical and allows rapid changes in potential to be recorded accurately. If $C\,=\,3.0\mu F$, what value must R have? [Hint: consider each leg as a separate circuit.]    $ \times10^{6 }\;\Omega$

  In Fig. Below a (same as Fpgpa(2 bkp/oc 2g vl)8ig. Below b), the total resistance is $15.0k\Omega$, and the battery’s emf is 24.0 V. If the time constant is measured to be $35.0\mu s$, calculate
(a) the total capacitance of the circuit    $ \times10^{-9 }\;F$
(b) the time it takes for the voltage across the resistor to reach 16.0 V after the switch is closed.    $ \times10^{-5 }\;s$

a
b

  The RC circuit of Fig. Below a (same as Fpl.f(5z5 nzh oeb/isbl46jyhb2ln, ;ig. Below b) has $R\,=\,6.7k\Omega$ and $C\,=\,3.0\,\mu F$. The capacitor is at voltage $V_0$ at $t=0$. when the switch is closed. How long does it take the capacitor to discharge to 1.0% of its initial voltage?    $ \times10^{ -2}\;s$
a
b

  Two resistors and two uncharged capacitors are arranged as shown in (Fig. Belo8 c(a bag,ha6tw). Then a potentia ,(aa8 6hatgbcl difference of 24 V is applied across the combination as shown.
(a) What is the potential at point a with switch S open? (Let $V=0$ at the negative terminal of the source.)    V
(b) What is the potential at point b with the switch open?    V
(c) When the switch is closed, what is the final potential of point b?    V
(d) How much charge flows through the switch S after it is closed?    $\mu F$

  What is the resistance of a voltmeter on the 250-V scale if the meter sensitijtfxaby5 7 in/3n+a* wvity isnwjtb yax+ a* f37in/5 $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensiti *( srhrjw,f9evity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resistance o1rgf spm en2k2 /2u2xpf $30\Omega$ and deflects full scale for a $50-\mu A$ current. Describe how to use this galvanometer to make
(a) an ammeter to read currents up to 30 A,    $ \times10^{-5 }\;\Omega$
(b) a voltmeter to give a full-scale deflection of 250 V.    $ \times10^{6 }\;\Omega$

  A galvanometer has a sennd3:zzlw+ v/ rsitivity of $35k\Omega/V$ and internal resistance $20.0\Omega$. How could you make this into
(a) an ammeter that reads 2.0 A full scale,
   $ \times10^{-4 }\;\Omega$ in
 ----待选择----parallelseries 
(b) a voltmeter reading 1.00 V full scale?
   k$\Omega$
 ----待选择----parallelseries 

  A milliammeter reads 10 mA full scale. It cons:/r au6nzxr9uck 2b 4iists of a $0.20-\Omega$ resistor in parallel with a $33-\Omega$ galvanometer. How can you change this ammeter to a voltmeter giving a full-scale reading of 10 V without taking the ammeter apart? What will be the sensitivity ($\Omega/V$) of your voltmeter?
$R_{ser}$ $\approx$    $\Omega$(Round to the nearest integer)
The sensitivity is    $\Omega/V$

  A 45-V battery of negligible int7qw7d4yr6 q iuernal resistance is connected to a $R_1$=$38-k\Omega$ and a $R_2$=$27-k\Omega$ resistor in series. What reading will a voltmeter, of internal resistance $95k\Omega$ give when used to measure the voltage across each resistor? What is the percent inaccuracy due to meter resistance for each case?
$V_1$$\approx$    V (retain one decimal places) % error    % too  ----待选择----uplow 
$V_2$$\approx$    V (Round to the nearest integer) % error    % too  ----待选择----uplow 

  An ammeter whose intedpqf *bhhk 7al 8z3 j8oo7,zx(rnal resistance is $63\Omega$ reads 5.25 mA when connected in a circuit containing a battery and two resistors in series whose values are $750\Omega$ and $480\Omega$. What is the actual current when the ammeter is absent?    $ \times10^{ -3}\;A$

  A battery with $E\,=\,12.0V$ and internal resistance $r\,=\,1.0\Omega$ is connected to two $9.0-k\Omega$ resistors in series. An ammeter of internal resistance $0.50\Omega$ measures the current, and at the same time a voltmeter with internal resistance $15k\Omega$ measures the voltage across one of the $9.0-k\Omega$ resistors in the circuit. What do the ammeter and voltmeter read?
$I_{source}$   $ \times10^{ -4}\;A$
$V_{meter}$    V

  Two $9.4-k\Omega$ resistors are placed in series and connected to a battery. A voltmeter of sensitivity $1000\Omega/V$ is on the 3.0-V scale and reads 2.0 V when placed across either resistor. What is the emf of the battery? (Ignore its internal resistance.) $\approx$    V（Round to the nearest integer）

  What internal resistance shoulv); sziumz s4*fyb5 r: n16moad the voltmeter of Example 19–15 have to be in errm)aru1v:b;z*45iyzo s6fsm n or by less than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) i)9pk/fjzzfp; s $35\Omega$, the high-resistance voltmeter reads 9.7 V. When R is replaced by a $9.0-k\Omega$ resistor, the voltmeter reading drops to 8.1 V. What are the emf and internal resistance of the battery?
r $\approx$    $\Omega$(retain one decimal places)
$\varepsilon$ $\approx$   V(retain one decimal places)

  Suppose that you wish to appzyf9 p6i+lx f:g.kw2 yy-ba 2ely a 0.25-V potential difference between two points on the human body. Thi: za2yypkw+ e96-lf gxb. f2ye resistance is about $2000\Omega$, and you only have a 9.0-V battery. How can you connect up one or more resistors to produce the desired voltage?    k$\Omega$

  A three-way lightbulb can produce 50 W, 100 W, or 15 f)fttv+xg:92xwc3nz 0 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individuvc) 39txnw+: tgz2x ffally or in parallel.
(a) Describe how the connections to the two filaments are made to give each of the three wattages.
50 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
100 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
150 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
(b) What must be the resistance of each filament?
$R_{50W}$    $\Omega$
$R_{100W}$    $\Omega$

  Suppose you want to run some apparatus that is 95 m fro2h n j62zoeobw5;pj*t qka92;u 4nv obn kn2*nm an electric outlet. Each of the wires connecting your apparatus to the 120-V source has a resistance per unit lengohnq;vo naezk j 2 pno;2n2t*j6 52nwk4b9u*bth of $0.0065\Omega/m$. If your apparatus draws 3.0 A, what will be the voltage drop across the connecting wires and what voltage will be applied to your apparatus?
$V_{wires}$    V
the voltage applied to the apparatus is $\approx$    V(Round to the nearest integer)

  Electricity can be a hazard in hospnq( f 9c*o*wkdzxt)8mi*1ortitals, particularly to patients who are connected to electrodes, such as an ECG. For example, suppose that the motor of a motorizfno)(ct9*rizod* *w q 1m8txked bed shorts out to the bed frame, and the bed frame’s connection to a ground has broken (or was not there in the first place). If a nurse touches the bed and the patient at the same time, she becomes a conductor and a complete circuit can be made through the patient to ground through the ECG apparatus. This is shown schematically in Fig. 19–60. Calculate the current through the patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must a 45-V battery expend to charge 0ofqcv 540*j fiov)fu a $0.40-\mu F$ and a $0.60-\mu F$ capacitor fully when they are placed
(a) in parallel,    $ \times10^{-3 }\;J$
(b) in series?    $ \times10^{-4 }\;J$
(c) How much charge flowed from the battery in each case?
$Q_a$ =    $\mu C$
$Q_b$ $\approx$    $\mu C$(Round to the nearest integer)

  A heart pacemaker is c5/drm mi.va4opr9y 0 g3)pbkl7z7 nw designed to operate at 72 beats/min using a $7.5-\mu F$ capacitor in a simple RC circuit. What value of resistance should be used if the pacemaker is to fire (capacitor discharge) when the voltage reaches 63% of maximum?    $ \times10^{-5 }\;\Omega$

  Suppose that a person’s body resir( op 5dt 9jnca0m/i1astance is $950\Omega$
(a) What current passes through the body when the person accidentally is connected to 110 V?   A
(b) If there is an alternative path to ground whose resistance is $45\Omega$, what current passes through the person?   A
(c) If the voltage source can produce at most 1.5 A, how much current passes through the person in case (b)? $\approx$    mA(retain three decimal places)

  A Wheatstone bridge is a type of “bridge circuit” usequ,3gnab5pj * d to make measurements of resistancp,n35j *g uaqbe. The unknown resistance to be measured, $R_x$, is placed in the circuit with accurately known resistances $R_1$ ,$R_2$, and $R_3$(Fig. Below). One of these, $R_3$, is a variable resistor which is adjusted so that when the switch is closed momentarily, the ammeter Ann Meter shows zero current flow.
(a) Determine $R_x$ in terms of $R_1$ ,$R_2$, and $R_3$.
(b) If a Wheatstone bridge is “balanced” when $R_1\,=\,630\Omega$,$R_2\,=\,972\Omega$, and $R_3\,=\,42.6\Omega$, what is the value of the unknown resistance?    $\Omega$

  An unknown length of platinum wire 0.920 mm inzcgiskzy91e 7,+v8 nt diameter is placed as the unknown resistance in a Wheatstonei +nkz9eyc sgt18v7z, bridge (see Problem 71;Fig. Below). Arms 1 and 2 have resistance of $38.0\Omega$ and $46.0\Omega$ respectively. Balance is achieved when $R_3$ is $3.48\Omega$ How long is the platinum wire?    m

What are the values of effective capacitanc2py d w/-sa ( n9zd24iu ;ds6vbjekn5me which can be obtained by connecting four identical capacitors, each havi 2m( n6n/;dw9jp24-zedbds5s y u aikvng a capacitance C?

  The variable capacitance of an old raw)zx;/p-pxsya w2/k sdio tuner consists of four plates connected together placed alternately between four other plates, also connected together (Fig. -/ ;s2p) w kpywxsax/zBelow). Each plate is separated from its neighbor by 1.5 mm of air. One set of plates can move so that the area of overlap of each plate varies from $2.0cm^2$ to $9.5cm^2$
(a) Are these seven capacitors connected in series or in parallel?  ----待选择----parallelseries 
(b) Determine the range of capacitance values. from    pF to    pF

  A battery produces 40.8 V when 7.40 A is drawn from it and 47.3 V when 2.20 6)h h n3)unkvoA is drawn. What are the emf and internal resis)n vh)nh63o kutance of the battery?
r =    $\Omega$
$\varepsilon$ =    V

  How many $\frac{1}{2}-W$ resistors, each of the same resistance, must be used to produce an equivalent $2.2-k\Omega$, $3.5-W$ resistor?    $\Omega$ resistors, each rated at ½ W, in  ----待选择----seriesparallel 
What is the resistance of each, and how must they be connected? Do not exceed $P\,=\,\frac{1}{2}W$ in each resistor.    k$\Omega$ resistors, each rated at ½ W, in  ----待选择----seriesparallel 

  The current through the +aj9 rom1 ag1y5a xy8m$4.0-k\Omega$ resistor in (Fig. Below) is 3.50 mA. What is the terminal voltage $V_{ba}$ of the “unknown” battery? (There are two answers. Why?) [Hint: use conservation of energy or Kirchhoff’s rules.]
right $V_{ab}$    V
left $V_{ab}$    V

An air-filled parallellu9v/c -e mis pr9.m1k-plate capacitor has capacitance $C_0$. If two identically sized dielectric slabs of dielectric constants $K_1$ and $K_2$ are inserted as shown in Fig. 19–64, what is the new capacitance? [Hint: treat this as two capacitors in combination.]

  For the circuit shown in(Fig. Below), ;p *sus7d3 llkdetermine
(a) the current through the 14-V battery $I_1$ =    $ \times10^{-5 }\;A$ ----待选择----downupward 
(b) the potential difference between points a and b, $V_a-V_b$ =    V

  A solar cell, 3.0 cm square, has an output of 350 mA at 0.80 V when exposwjhw z.78oine+w 6w fk+6bwy 1ed to full sunlight. A solar panel that deliv f7niwh6 6zbwwojyk+1+8e. wwers close to 1.0 A of current at an emf of 120 V to an external load is needed.
How many cells will you need to create the panel?    cells
How big a panel will you need, and how should you connect the cells to one another?    $m^2$
How can you optimize the output of your solar panel?    banks of    cells in series per bank, with the banks in  ----待选择----parallelseries  always have the panel ----待选择---- pointedturned  directly at the sun。

  A power supply has a fixed og55sbtco *u(h6k kurf;. lxq:t3hfbd7 s o:6autput voltage of 12.0 V, but you need $V_T\,=\,3.0V$ for an experiment.
(a) Using the voltage divider shown in (Fig. Below), what should $R_2$ be if $R_1$ is $10.0\Omega$? $\approx$    $\Omega$(retain one decimal places)
(b) What will the terminal voltage $V_T$ be if you connect a load to the 3.0-V terminal, assuming the load has a resistance of $7.0\Omega$? $\approx$    V(retain one decimal places)

  The circuit shown in (Fig. Below a) uses a neon-filled 8sql6lx 9:ma qtube as in (Fig. Below b). This neon lamp has a threshold voltage86 la:x9sm lqq $V_0$ for conduction, because no current flows until the neon gas in the tube is ionized by a sufficiently strong electric field. Once the threshold voltage is exceeded, the lamp has negligible resistance. The capacitor stores electrical energy, which can be released to flash the lamp. Assume that $C=0.150\mathrm{~}\mu\mathrm{F},R=2.35\times10\mathrm{~}^6\Omega,V_0=90.0\mathrm{~V}$ and Ann meter=105 V
(a) Assuming that the circuit is hooked up to the emf at time $t\,=\,0$, at what time will the light first flash?    s
(b) If the value of R is increased, will the time you found in part (a) increase or decrease?  ----待选择---- increase decrease 
(c) The flashing of the lamp is very brief. Why?
(d) Explain what happens after the lamp flashes for the first time.

a
b

  The current through odl eydi22ld46w8fb 04ehwcg6 y2 e,ithe $20-\Omega$ resistor in (Fig. Below) does not change whether the two switches $S_1$ and $S_2$ are both open or both closed. Use this clue to determine the value of the unknown resistance R.    $\Omega$

  In the circuit shown in (m 8y4+ )hbxbmag(jri6dh: za*Fig. Below), the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance of thm( pf3oq a::oge circuit shown in (Fig. Below)? $R_{eq}$ $\approx$    $\Omega$(retain one decimal places)
(b) What is the current in the $18-\Omega$ resistor?    A
(c) What is the current in the $12-\Omega$ resistor?    A
(d) What is the power dissipation in the $4.5-\Omega$ resistor?   W

(a) A voltmeter and an ammeter can be connected as show0wvuk(wd/+x:jgq xj0jus lp;/o:z k/n in (Fig. Below a) to measure a r0/;quxgw+x sl /k:pkwz/0jj(uv:d ojesistance R. If V is the voltmeter reading, and I is the ammeter reading, the value of R will not quite be $V/I$ (as in Ohm’s law) because some of the current actually goes through the voltmeter. Show that the actual value of R is given by
$\frac{1}{R}=\frac{I}{V}-\frac{1}{R_\mathrm{V}}$,
where $R_V$ is the voltmeter resistance. Note that $R\approx V/I\quad\mathrm{if}\quad R_\mathrm{V}\gg R$ .
(b) A voltmeter and an ammeter can also be connected as shown in (Fig. Below b) to measure a resistance R. Show in this case that
$R=\frac{V}{I}-R_\mathrm{A},$
where V and I are the voltmeter and ammeter readings and $R_A$ is the resistance of the ammeter. Note that $R_\mathrm{A}\quad\mathrm{if}\quad R\approx V/I\quad\mathrm{if}\quad
R_\mathrm{A}\ll R.$

  A flash lightbulb rated at 2.5 W and 3.0 V is operated by a 9lm7vjdc-h p)vnb1f59.0-V battery. To light the bulb at its rated voltage and power, a resistor R is connected in series as shown in (Fig. Below). What value should the resif1jb- n7vh cv) 9lmd5pstor have?    $\Omega$