Explain why birds can sit 6gh/g;uv ( 5ktntj dee ai ol943ps).yon power lines safely, whereas leaning a metal ladder up against a vh y4; 6g ens oalp3/9j).ug5ttdik (epower line to fetch a stuck kite is extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree lights c*n*-rb wieum2 ju3;wwly (ts4onnected in parallel versus those connected in ser* je-uywsr;b4m wnw(l3tu 2*iies.

If all you have is a 120-V line, would it be possible to light sejvc5x(w5e t *everal 6-V lamps without (5evt5 *ew xcjburning them out? How?

Two lightbulbs of resistancew; j6 2xa;elxa $R_1$ 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. Are these connected in series or pa1nj6xd wef1i *ralleiwfx 1d6ejn*1l? How do you know?

With two identical lightbulbs and two identical batteries, how would you a8qkbe,k6e3 ae rrange the bk3 8aee6, qkebulbs and batteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in series to a battery, does the batt.h w/t5 htzq20qjv i1 tujaq.2ery have to supply more power or less po. quv0.a2jtzqhqjh 51tiw2t/wer than when only one of the resistors is connected? Explain.

You have a single 60-W t0k-i vo*zm-ar1ul9s bulb on in your room. How does the overall resistance of your room’s electric circuit change when you turn on*kmal os -iv- 1r9tz0u an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as(lou )oj+u3pvs d5gy. in Fig. Below), does the sign (or direction) of a battery’s emf depend on the direction of current through the battery? What about the terminal vol+5guo)uo v sy(dp3j l.tage?

  Given the circuit shown in Fig. 19–36, use the words “increases,” “decreases,” ,y+wwkw5i 2 )g 1c6ipncd q:neor “stays 1egww5 iic d 2k6cy+)wnn, pq:the same” to complete 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 connectea kl w3u xc*+izi2scr,d(q,2rd in series? For what use are they connected in parallel? Does 3dka lr, i2x+ciurz q, (w2s*cit matter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery everse1ccai :tm m250ogw20 j xc9gw6ha yol8d1a7 exceed its emf? Explain.

Explain in detail how you could measure tcel4a2nu l 3p*he internal resistance of a battery.

Compare and discuss the formulas f3dxp 3q )y6ha hkt9i/uor resistors and for capacitors when connectedxqtuh/ai3k y p93d6h) in series and in parallel.

Suppose that three identical capacitors are conr smp rws65 1)3bt/o -b.deystnected to a battery. Will they storobew.s6)b/ 5r dts-1 pmtsy r3e more energy if connected in series or in parallel?

Why is it more dangerous to turn on an electric appliance w.fy8 9q9,;yodaqsg mh,qel +phen you are standing outside in bare feet than when you are inside wearing shoes with thick soles?qsop.+med8,fy, ql9h; qyga9

(Fig. Below) is a diagram of a capacitor (or condenser) microphone. ;q*u(poq vnacuk8d) )The changing 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 freqk ;quanod() p)8c*vuquency as the sound wave is produced.

Design a circuit in which two different 22+ zc .k:ihz(kie1 b;lcwwmz switches of the type shown in (Fig. Below) can be used to operate the same lightbulb fro;mwzhlk b1 .+ze:cw czik (i22m opposite sides of a room.

In an RC circuit, current flows from the battery until the capacitor is c ,w fp6m 0tpq-pdz+zj,ompletely - pzpzqftpw, mj,d+60 charged. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If not, where does the extra energy go?

What is the main difference between an analog voltmeter asue i*)zb2u9q nd an analog ammeter?

What would happen if you mistakenly used an ammeter where you needed to use a vacpghp( chk 3 t)hm/1;2lwd.v e,lxv-oltmeter1 la wecph),g dk2v3v . ;l-mcxthp(/h?

Explain why an ideal avg(gtlg 3 f3hoyy6m, 4mmeter would have zero resistance and an ideal voltmeter infin3 g(4yy,hg6lv3 om tfgite resistance.

A voltmeter connected across b08 /r/7fgvyul ,natx a resistor always reads less than the actual voltage across the resistor when the meter is not present. Expl v yx/8l0,ur/7gab ftnain.

A small battery-operatedl oow +qb8kojz7./.eo 9i**zjxr9ww p flashlight requires a single 1.5-V battery. The bulb is barely 9+lr7*ozobw.kw pe9. zx/ *ioqwoj8jglowing, but when you take the battery out and check it with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an internal resistanced mbo evn f7tw95e (76eot5p/a 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 resistr3ni2/o 3 ;(sucbavh +d a-spcance 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 have a:j djp4jb9 2iz $680-\Omega$, 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 havcuw -2uual9t76u bn f5e a $6.0-V$ 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 of0rx jf5uolwr-+89 d bd2 odxb* $12.0\,V$ 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 a 6pz e kbt,5pb5$110-V$ 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 conscc- lom55l)0 woz 9zonected in parallel 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 electric circuit reveals that a :iu 8v/jgqqxm 84i78s 4dd2(auolt b v$480-\Omega$ 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. Below). Answer qualiy aux2kd6 gip)a0w*q/rear:.ij l *)ytatively: gx w6*ya2j).alr i: kqa*diur0 eyp)/
(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 circuirqau.cqw )nb z2jh0 nj:40z( nt connected to the battery in (Fig. Below)? Each resistaur4 bj)qhq0(0c. 2 njw zznna:nce has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connecteqic:8e n5y l0g+ 8uzqed to a battery as shown in (Fig. Below). Qualeinuy:0 8q+5 e zq8gclitatively, what happens to
(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. Below) and show that thb2n ke2*9-b3 nt n,u byz7xxnje sum of all the voltage changes around the circuit is zexe n9tbu,n-bn2 jkb*n73zx 2 yro.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal voltage of each battery in (Fig. Below). 18V batteryb8ch.dpapw 5lfx :c )8 =    V 12V battery =    V

  (a) What is the potential difference between points a and d in (Fig. Below a) (tzh/ b( )nsk 07qig*5hpf0. b kz*mdkygx.5kwsame circuit a5kb*w0/)5hhz*kz nf s pmkd.x. 0yb g qigkt7(s 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 vm-(szbl ae, y,i)jg7), find the potential difference between points a and b. Eachb je(-y)gm zi7va,,ls resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the currents througw+zhs9nc;ap ewv ma:y2 a (zmx+o.l*;h $R_1$ 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 that each battery has an inqb*8 h.)fk) bwzbx*dxternal 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 the currents in each resistor showronk+0qv7;z(1 yie bxn in (Fig. Below). The bat0bqxnr1vk eozi+ ;7( yteries 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 has internasc,vpi.1rd8n l 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 each resirr.ar(h )-r mm8q/xrkx r(r l4stor of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currents mfno q3 2jem(01h7rp w$I_1$,$I_2$, 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 curren.vh*d+x.j4 bwxes xl9t $I_1$ 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 emfs of 2.j3gmwl:h0:gv0f 8rh g6 k,lwz 00 V and 3.00 V, are connected as shown in (Fig. Below). If each internal resistance i6wkw0lzg,j: g3r fh8:0lgm hvs $r\,=\,0.100\Omega$ 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, of cmc ccg,1 hf;m ;kkvu0 :.igk1gapacitance 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 whole network of (Fig. Bep(pm 0z6nut6h0 +xl0jgp0z colow), calculate the voltage across eap0tl6 zxpcp(znm0j0og+6hu0 ch capacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of a circuit is to be reduc fce (b2ptz,+25utptxed from 4800 pF to 2900 pFcu2(zpbt,+ft5e tp2x .
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 wa n.hedwh)bg /(s accidentally constructed 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 /ls4ied:a b z 1pz9yyur(4 h.yshown in (Fig. Below).

  In (Fig. Below), if c1mv1,z+e 4s:;l8fkrtku o 2g ccjc7s$C_1=C_2=2C_3=22.6\mu F$, 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), supposesmax k9t /mmj/uy*i25 $C_1=C_2=2C_3=16.0\mu F$, 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 ;)pl.5b qro sb$V\,=\,78V$ 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 platesu/ks2u.7,sq-: cri w uhrtm.f, each of area A, are connected as shown in (Fig. Below). ush:,q2 / tu.rcsum7i.-kfwr
(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 single 250-pF capacixokfwo 3*. l.p q70-m0 uwyej6mg7aqv tor hooked across a battery. It is desired to store three f7oy.qoe *p majgx0vmk7 3.0lw -6qwutimes as much energy in a combination 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 connected ini(bsl-5y9zrm tx 2.po 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 plates, what is the unknown rb.-ysp9o2x ti5m zl(capacitance?    pF

  Electrocardiographs are often connected as shown in (Fig. Below). Ti8sj gg:z08szal 3kg tp7o5k ;he leads are said to be capacitively coupled. As80kig p;t 7gg3lzzj ks5o:a 8 time constant of 3.0 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 uy6p-go+gfdw8xf f2. as Fig. 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 Fig. Below b) z:, :hpqe3dqg 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 capacilas2au(w0 v384xu8tz.c si9vjkkl ( htors are arranged as shown in (Fig. Below). Then a potential difference of 24 V is applied across a0u8(lh49tvs cl 2svzik3(ku 8.x ajw 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 eec**6 x0yuch(o6z qwscale if the meter sensitivity isz 6 uwe(eco*6hx*cq 0y $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensi.v wj1a8 kxck6m6 9+poo rfk0htivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resiu:m/n4*xf a ae7p4lq jstance of $30\Omega$ 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 sensitivw js1 d,m+()l+ddp ixpity 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 m,) p9td4aurmewtw )2v 2hd4k e y.;w/jiaj(akA full scale. It consists 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 internaf0. v6p,bsq qzl 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 internal resistance i b:68uqpr7vp gs $63\Omega$ 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 should the voltmeter of Exazmp /o 8kao9/vmple 19–15 have to be in error bmooz98k /v/ap y less than 3%? $\approx$    k$\Omega$

  When the resistor R in /cb)k5 qns+ yb8cfr:d (Fig. Below) is $35\Omega$, 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 2 wpf2uz9x/mr apply a 0.25-V potential difference between two points on themfr/x2p zu29w human body. The 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 150 W, at 120 V. Such a buaro-1ywe7nw. .qdyh* jm 8(y xlb contains two filaments that can be co y. dj1.*hnyywrm8(owexa- q7nnected to the 120 V individually 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 ipiux)/ y- lfo)osl.egmz 0;w. s 95 m from an electric outlet. Each of thl/i.))g0wsfo -oxule;.zmp y e wires connecting your apparatus to the 120-V source has a resistance per unit length 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 hospitals, particularly to patients who are qbc80p 2-mxwcconnected to electrodes, such as an ECG. For example, suppose that the motor of a motorized pm-w8bcc 0qx2 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 li* a5:fp;cy ( fpuc8dbattery expend to charge 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 dr +f2omy0rl 8sesigned 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 resis n:7)iapezdsr9ubq - cu.*o b4tance 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 ty : olak n-uw-i,u4f-2bzk4nom pe of “bridge circuit” used to make measurements of resistancekaolk4- uimn n2b- ,zwo4-u :f. 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 in diameter isis88a e4q fup7 placed as the unknown resistanf87squ a4ei8 pce in a Wheatstone 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 capacitance which can b8y n0:zhy 35ps)mlxgtyg n a0/e obtained by connecting fxyn y0ps) hzt8lagn:m /0yg35 our identical capacitors, each having a capacitance C?

  The variable capacitance of an old0tfs 745s6pj9eagis v radio tuner consists of four plates connected together placed alternately between four other plates, also connected together (Fig. Below). 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 eacpg t5ia6se 9s 74sfj0vh 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 - ngrueoj/5pcu r2* e8V when 7.40 A is drawn from it and 47.3 V when 2.20 A is drawn. What are the emf and internal resistancr *n g/e5jpc-u 82oreue 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 ty (.dn9fx+zhsuo9 ud p+8n w2fhe $4.0-k\Omega$ 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 parallel-plate bu: uqn(7zxksy)m+ / bcapacitor 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 ik4.fe23 7 zhvejxkw+ 49vs* xfx.xkqa n(Fig. Below), determine
(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 sqt9n sio.-d p+ fb9gut2uare, has an output of 350 mA at 0.80 V when exposed to full sunlight. A solar panel that delivers close to 1.0 A of current at an emf of 120 V to an exp.b-f9tso+n2 u g9idt ternal 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 out54knag1 *h nc,birx +rput 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 tube as in (Fign n(1o+qx:q/ ;rhgwqr. Below b). This neon lamp :nwnhrqr/x;qo ( q +g1has a threshold voltage $V_0$ 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 tw5c x6z8zcg 9the $20-\Omega$ 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 (Fig.,y dz cl)9-boa 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 the circuit shown ,z7 asp w/p2uf9tk.g qin (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 anhvl40xo+8a8 o/9zfb:spm6)fchgb vkgfu 3y6 ammeter can be connected as shown in (Fig. Below a) to measure a resistance R. If V isff bh8o 4op89c0kx/f6:+mhz as3gv6 )uyg lbv 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 2.5c) +a7fn 1tp/clna8mfx kfdc3-nce7 ) W and 3.0 V is operated by a 9.0-V battery. To light the bulb at its rated voltage and power, a resistor R icfc l n7ta n7+d)kefcx caf/8mn)31- ps connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$