Explain why birds can sit on power lin 7cpje5li:v;) wccng/ es safely, whereas leaning a metal ladder up against a power line to fetch a stuck kite is exvni5w7; cpcc:)/ gle jtremely dangerous.

Discuss the advantages an (-v1 g8n,)x n9m0m0beb7znssdee -mqjmo-yo d disadvantages of Christmas tree lights connected in parallel versus those connected in series. semxne7n(gjm-m1-)b bvdz 0n smeqy0 o9,8o -

If all you have is a 120-jt/e+v )o 9.l,agsvud8hrv:v V line, would it be possible to light several 6-V lamps vv8h so ,j a:/v)g vdet.+ur9lwithout burning them out? How?

Two lightbulbs of resistance x6e p/mb bk:dj3 c8v:z$R_1$ 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 double2lz y-i q18hbee 7 2jv-vhws-xeg2vs 4 outlets. Are these connected in series or parah--s qj 2zg2i hvwbeeyls42ev-vx781llel? How do you know?

With two identical lightbulbs and two identical batte g7- mh8la 8dqbya5w+iries, how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligible internal redqy wb758am+-8lg i ahsistance.)

If two identical resistors are connected in series to a bciwhb;i 2r9/n attery, does the battery have to supply more power or less power than when only one of the resistors is connectew;cir/9nb hi2d? Explain.

You have a single 60-W bulb mkql+ )j 0.fi 1 l:k(yxhhh6d e8p(ukk2/ txzron in your room. How does the overall resistance of your room’s electric circuit change when you turn on an additional 100-W .rj0phz1 xkmuk/d28k (el)f( :hlkt6iqxy h +bulb?

When applying Kirchhoff’s loop rule (such as in 8zaqmem 03.bds4)twz Fig. Below), does the sign (or direction) of a battery’s emf depend on the direction oq 0ba3w.z e)4m8 stmzdf current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, u y/0455h8vqva tgx 8rlji atv*se the words “increases,” “decreases,” or “ tyit0 hv5r54vv8jagl8a/x* q stays 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 connected iua3 abkuay fmpzrk u78o,pb 2 ,ngy3+0 -dg87jn series? For what use are they connected in parallel? Does it matter if the batteries are nearly identical or not in either caz +3 pna7u gku,b2p8jyrb738a ua-,y okfd mg0se?

Can the terminal voltage of a bnd0z k4 +lhb 8)zpzx;uus.2nqattery ever exceed its emf? Explain.

Explain in detail how you could measure the internal v9ov5f;acw+w k mm 7k4tf :sr,resistance of a battery.

Compare and discuss the formulvuo0wl b ;0b-sas for resistors and for capacitors when connected is ; w0o0vblu-bn series and in parallel.

Suppose that three identical capacitors ar1 k7e*f.r0nxozv wae. e connected to a battery. Will they store more e. xnvwa*.7e1 f ke0rzonergy if connected in series or in parallel?

Why is it more dangerous to turn on an electric appliance when kubz-ac 1 cu2us*7xj25 l9wvgyou are standing outside in bare feet than when you are 915uau wb*xlcg7uj- v22s kczinside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or conden/1+g nlx))dz w glwpj+p+gmils ,h c8/ser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to move back iwwhx+ g/g8 /gzp)pll,sl) +dc1m+ njand forth. Explain how a current of the same frequency as the sound wave is produced.

Design a circuit in wqtjn+ibto:sjtyw) ,z6 4 c: 6ziwo(+n hich two different switches of the type shown in (Fig. Below) can be usewt+ioz6i4sty 6n (qw,nbt :+j:j z)c od to operate the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from the battetn; h1f/vqfs kubyi.4 md7s24ry until the capacitor is completely charged. Is the total enerth. m/ ks2 1vfqs4;fi nyu4bd7gy 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 1/ lhw::2(uz4 -wc op tbcgvgm+6fkifand an analog ammeter?

What would happen if you mistakenly ugq 7t:b0an*fn sed an ammeter where you needed to use a voltmnf0t b7:a*n qgeter?

Explain why an ideal ammeter would have zero resistance and an idealyo uyia fp:jkon/.a1e. 2; m3l voltmeter infioo;13 n./ ak.m y:yifeu pjal2nite resistance.

A voltmeter connected across a resistor always reads a x:4i4l h2j,hxtu1 skless than the actual voltage across the resistor when the iaxlthsh4j:kx 41 u,2 meter is not present. Explain.

A small battery-operated flashligh4d.t9,h p3elv3rc;(0j lnoaqh fn o f6t requires a single 1.5-V battery. The bulb is barely glowing, but when l3rfv;4ncnd3ftqo h (.pl9oh ,6j0ea 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 resistance *, s yh u/*ts wrz/ag (+bo*wif*-lkzfof $0.900\Omega$ 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 co) ,zfxvw(hp0(qf, mresistance 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 havey 6icd,ia tw+ mz2j5h* 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 havet. :o7wvmwq+w4-w cis 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 of rhm bhspxc(( 2: yw:z9scw2,d$12.0\,V$ 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 i1c/xa,id rv2+yl 7f9c unyh )ln series across a $110-V$ 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 parallel t:znx.s5cegt9 f19w fo o 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 $    $\Omega$   

  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 thatgev5wa4:l7* p/ny0 d .q oqk5 lt2vslo 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. Below). Answer qualitativ4gvs+ xzmmtwrfynk-u ) l- 368ely: uz4n -sg6)+x8yflmt mw - v3rk
(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 co nry8r up,g-gn:z -a:mnnected to the battery in (Fig. Below)ypun8,mgrn:-r :-agz ? Each resistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown in (Fig. Berzc6t/9 /ez-p p-9g8kk9o,lez dpfmdlow). Qual rdm6c/z,o9--ket8 /lekpgfp dz99pzitatively, 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 jngpuypex-tl(thh s;k6 6.7 llw440y the sum of all the6glt76; 4ple .jx4utn-l hwshkyp 0(y voltage changes around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each bajq2 k 36 d69y:0l eg y6ocd1isnxz7gpxttery in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential difference between points a and d in (Fi fhgfkj2 g+u vjx zl;);9 7id1za5j+vvg. Below a) (same circuf97f5x;gk)dzv+jajg;iu 1v jvz h+l2it 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. Bet (xiz0 gux.0clow), find the potential difference between poig0 x(0ixczu.t nts a and b. Each resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudee1plp 0: 1e:ndu-fczbs and directions of the currents 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 xx6c;y63cj0w(c l1nmm2 a gco assuming that 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 ani25 fahr1( jbvd directions of the currents in each resistor shown in (Fig. Below). The batteries 2(1rh jiav fb5have 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 4- aof sp-ka2fhas 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 2nf1x7cev0g 1g pkxq87qo1uq each resistor of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curkmnk0 4me/g1urents $I_1$,$I_2$, 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 currente 3: p v3,xptvz:boq0q $I_1$ 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 emfsd ki 5,.pagiv1tyj+ k9 of 2.00 V and 3.00 V, are connected as shown in (Fikp1 v j9kady,+ti.5igg. 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, of cap6 1 g7qgqwlo+jacitance 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 ne /1 scp5d 3ngryqj2.petwork of (Fig. Below), calculate the voltage across 3g c.5 qre2n p/j1dpsyeach capacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of a circuit is to be reduced from 4800 4spo3qish0x*pb o u)9pF to 2900 pbshxq0 o9ou p43)*is pF.
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 accid3mprvp5l /y 53z y.sxgentally 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 shown in (Fig. Belowa jyr g9.9jfa+).

  In (Fig. Below), if /)c9g)/f1 fk xnedudj,s+ cad $C_1=C_2=2C_3=22.6\mu F$, 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), supposeu/6oriy2ca3g o- a8cg x4;tsh $C_1=C_2=2C_3=16.0\mu F$, 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, h2kd*ee/viojs 59z l $V\,=\,78V$ 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 con10rqck utoiv1ufgtf 41c9at:: fsn+6 nected as shown in (Fig. Below). 1ctvo:ungir 401ftsfc91k + f 6aq:ut
(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 capaci -my8+)gqcjl ytor hooked across a battery. It is desired to yyml8gc+j-q)store three times 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 in series with an unknown capacitance, and 7c tedd67b0 0mabpg c:as a series combination they are connected to a bagad pmb 6cet:7cb00 d7ttery with an emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often coar9yl:eiq 2wq uc.0/ dnnected as shown in (Fig. Below). The leads are said to be capacitively coupled. A time constant of 3.0 s is typical and allows rapid changes in potenti0/yr 9ql.ca ewd2qu:ial 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 Fig. Below b), t*3e 9mvwe o e4os+l46ymxq ikmvc 30j 0q62rxlhe 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 Fzbtv z3)6/)n)z 3 h j9nsywpkoig. 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(6w0 m8crxppeek mz w(o s,m98 uncharged capacitors are arranged as shown in (Fig. Below). Then a potential difference of 24 V is applied across the combination as shke(so0xz( 8p,m pww896 cremmown.
(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 sensit(u 2hwjb*2i bj7.decdivitbdej2bij.hdw7 u (2c* y is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a senzuw )5g mpvh1ts+o4-psitivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an inte/,krml j 9ao0irnal resistance 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 sensitv3j z.i:ktgw12or d3 nivity 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 consists or*tc(i rwp)5 u lj7icj 1t t6ygdp4n(-f 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 internal resistance is connected to a /9rn.,ohpy3pwcvl 1 o;hyr v 9$R_1$=$38-k\Omega$ 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 rej h6k0ul2lu+squk0x 8 n (qze+sistance 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 should the voltmeter of Example 19–15 ho v97s 6yc*apzave to be in error by less than v zcpoys67*a93%? $\approx$    k$\Omega$

  When the resistor R ) e-*.jze0 dsa 5cofl; znf8agin (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 apply a 0.25-V potzih4w 4f.jf 0 cb.on(bential difference between two points on thbfz b(4oc0 hj. f4nw.ie 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 1g3 +vdhfpd0v+ dvqj0 rupr7;f615 uhlx w,x3h20 V. Such a bulb contains two filaments that can be connected to th 3 6u 0h,+1vrq;d+v5ddvxpr x0f7g3 pwhfjluhe 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 ax7)gmkic--7 eaixwo 8pparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus ticx 7ixw8-ke )ao-gm7o 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, pa9wvzt1 1jhrad:wug;dq 6 , a-irticularly to patients who are connected to electrodes, such as an ECG. For example, suppose that the motor of a motorized 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 mdjr haqwi1g1 z,w:6 vau9td; -ade 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 y0 g*;nkkbd8d a 45-V battery 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 issez vf* f8 nt4i i(-h)m8muyl9 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 resistaeie2 rd:2z*gcnh 2yq47c x 8h(nqgn1tnce 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” un9-.nv t 1mhj,yn .qqqsed to make measurements of resistanmq.y,-t vq 9nh j.1nnqce. 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 is placed as tix95f6jf i(pzx nur(a:1fw -l he unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 anw5x lpfr(x:( ziu1f69 jfi a-nd 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 be obtained by z,c ap9jpt h*e6lc-uh*ai07nyv 4* ioconnecting four identical capacitors, eachl7 v eazh,-4*0uij9iycn *cot h *pap6 having a capacitance C?

  The variable capacitance of an ) +szxoi hbij3p89 -yxold 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 neighborz8+b-)p9ihoyjxix3 s 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 7c)uaa0;:wynl /g e u:z.40 A is drawn from it and 47.3 V when 2.20 A is drawn. What are the emf and a)0 uag/;w ecl:y zun:internal resistance 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 1j5tt7v xp., cg/z whithe $4.0-k\Omega$ 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 4n-q:-x zvyagyw 0u12pf hw2 vcapacitor 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 idb+rpp/ 36+va yi6 tdtn(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 square, has an output of 350 mA at 0.80 ,yzz qi4wwvm6t vt2rs:x,;5c V when exposed to full sunlight. A solar panel that delivers close to 16x,5sw;ymvr ti tv2zcw,4 :qz.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 output voltage9brr7l v,( *, s1(yz xqhosg avzie:d9 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 (Fyvt6(d.- rgfi ig. Below a) uses a neon-filled tube as in (Fig. Below b). This neon lamp has rtvdy gf.6i(-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 tz8 +kt+ sg7ut u*pqr e-fw+c2uhe $20-\Omega$ 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 ph7np0m : n4)/i6xdr7blya 9g 4wev7ox d.eip(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 the du 5 1w+fq-zpra) 2cdtcircuit 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 opbvsn ..:pwx 5;7,w1oxc qqlz r 9g+aan ammeter can be connected as shown in (Fig. Below a) to measure a resistance R. If V is the 7zxqa. lqbp+rc 5ws:gv ;9ownp.1ox, 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 ;n a 5yrv0epvcu43k3bfhx7v 2W and 3.0 V is operated by a 9.0-V battery. To lighv;buv 3f xkv 5ae7pr3y0c2hn4 t the bulb at its rated voltage and power, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$