Explain why birds can sit on power lines safely, buysh33qgx ckq /s;.; whereas leaning a metal ladder up against a power line to fetch a stuck kite is ext3b./sxqgyqs uk; ch3;remely dangerous.

Discuss the advantages and disadmn qmqnb 8)2/mai* h/tvantages of Christmas tree lights connected in parallel vm/m2 i m*h 8ntab)/nqqersus those connected in series.

If all you have is a 120-V line, would it be possible to light several 6-V lv0z, nw,ziqv-mykqbz le z, n /hb:m*l m855:jamps witho leb jb zvm/lv0: 8,wzqnz,n,: q h5i-mmyz5*kut burning them out? How?

Two lightbulbs of resistance8/pp 0 ufqngn6 $R_1$ 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 conneczrd(c:/ m0ds- ggz,szted in series or parallel? How do you md,(rg0 szs-cd zgz/ :know?

With two identical lightbulbs and two xq8yaxm )dfhr6o 8a. /identical batteries, how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligibq8 /6amh)x.dofxy 8a rle internal resistance.)

If two identical resistors are connected in series to a batt gu9say 0ry :vf ,);bbl9qkwe., z-zzwery, does the battery have to supply more power or less power than when-,0 )vgquy;,.br ksbza9w9lzewfz: y only one of the resistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the overal:he/ho 4p(; wca scy+cl resistance of your room’s electric circuc;ysoe(: h+hca /wc4pit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below),ue50si77rq is4g/pc g does the sign (or direction) of a battery’s emf depend on the direction of current through the battery? What about the teus7/0 p7siqc eig5rg4rminal voltage?

  Given the circuit shown in Fig. 19–36, use t:y/g8 vwsafsqq;;7r she words “increases,” “decreases,” or “stays the same” to co7ag fw ;s;:vqrssq/y 8mplete 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 colio,hi.9aju 22rkkb2q:efqe9 ;mfp1:x q yb0nnected in parallel? Does it matter if the batteries are nearly identm9. :k2p:0u;,qjq exq92ei yk lirabbf1ofh2ical or not in either case?

Can the terminal voltage of s fh*/ ydv(c-no7iq,g4c*n nqa battery ever exceed its emf? Explain.

Explain in detail how you could measure the internal rsj19fi9m3:w6a hkxmk esistance of a battery.

Compare and discuss the formulas for resistors and for capacitoyf,ruc; ra88. ukjnyze8c.* jrs when connected in series and in parall.creayk ,nj 88 zucufy;*. 8rjel.

Suppose that three identical ca dx3c+lw-dsc-pacitors are connected to a battery. Will they store more energcdls c3-+ d-xwy if connected in series or in parallel?

Why is it more dangerous to turn on an el+v)6 j- /j(eh4gr yeruah; t. bfwn8eeectric appliance when you are standing oyu (;evg jh-fw6)+r 8.n4rbejeea/h tutside in bare feet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor ( *am +e(ap0v4mbgv c6oor condenser) microphone. The changing air pressure in a sound wga6 vb p*ma0v(o4m+ecave causes one plate of the capacitor C to move back and forth. Explain how a current of the same frequency as the sound wave is produced.

Design a circuit in which two different switches of the type shown in (Fi itadp k-5+jp25cm+6dh2zr hzg. Below) can be used to operate the same lightbulb from opposit52 i+mzh+p 5 jdrtha6k -d2zpce sides of a room.

In an RC circuit, current flows from the battery un ,jo 4xojvh13zixf2:yn:n x gm6 :j)omtil the capacitor is completely charged. Is the total energy supplied by the battery equal to the total energy stored by thji6ov4 m: j,fj:x1mo3 ygzn:n xo2 xh)e capacitor? If not, where does the extra energy go?

What is the main difference between an analog voltmeter and an, 3 k yg(kk)6i8xvpoks analog ammeter?

What would happen if you mistakenly used an ammeter where you needed to use a zvyr ,y2.m.db p/sp6fsdxsn0 7ew:u: voltmety 0nsbudsd7wp se2 v:r.mf : y6.p/xz,er?

Explain why an ideal ammeter would have zero resistance and ankdvn7x)/kts 7 ideal voltmeter ixt)nkdk /7 s7vnfinite resistance.

A voltmeter connected across a resistor always reads less than the actual voltae+1:yo 3 e+u5uyss wflge across the resistor when the meter is neeuy ou+3l5y1:+ fwssot present. Explain.

A small battery-operated flashlight requires a single 1.5-V batterz gxez w1h.4c m-85 .kqx)egldy. The bulb is barely glowing, but when you take the battery out -g .mc4gd1 xz ewq58ekzx).lh and check it with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltaxgdezt,*e9 p n57xi) ch;ji gt0b:(w jg3t/rpge for a battery with an internal 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 resistance of a 1idx 8ye9r2r n$12.0-V$ 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 e/i9acdo67 wcte 99k8lwhd6oa $680-\Omega$, 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;tzid k:h92 l7lq a qd97y8ikqs5 )pbq 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 em :wlr 5i tei9+7wcpsirg)5( vpwtow66f of $12.0\,V$ 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 connelrj0rt3e a nw6b0 ;,pdag5y/ dd mh,i;cted in 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 parall6+cey kl+nk(/s c *yxoel 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 $    $\Omega$   

  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 reve) xt dezvr460o /m)jnnals 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 iilgg sw .m;wiq*32j9l z1 j+ign (Fig. Below). Answer qualitatively: 2 gwiz+9mjjw.1iigll *3q s;g
(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 resist 8yzc km(n4u4eance of the circuit connected to the battery in (Fig. Below)? Each resistance cu8ym 4ez(4nk has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connec rly vn.q6ml9(ted to a battery as shown in (Fig. Below). Qualitatively, wha(yn.m vlr9q6 lt 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 thatzs pf.q y .j-n7tzm5l/ the sum of all the . /fsjyz7q5plnzm.t-voltage changes around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of eachubl em4:m7fu w,,+nx c battery in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential difference between points a and d in (Fig. Belo+c4r6 xh. zfyp;y7 snsw a) (same circuit as Fig. Below b, )pr;.cy 6zf 4s7 +xshyn, $V_{ad}$    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 the potential difference between p2 8-tkosi jc vn,,v5eubg.h5noints a and b. Each resistor tu58 5scvn k,jo-.ivn2,hbeg has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitu4o0)v0q (8v ; nfce wx7bfswixdes 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 assuming that each battery has an 3fdwchv21ohhpxx9 yng- ;u ;t :ey*5qinternal 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 shown wkyz9f 3jz,m:in (Fig. Below). Thz3jkyw:9m,f ze 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 batts7n1*0 huexv ,n xe2u,rdqzx1 ery has 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 each ol)qfx, 6*wa pm0nwt;i,57 a h+wsbeeresistor of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currents +;qpap nxbwh/ -;:sff$I_1$,$I_2$, 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 current u:/at5hd i2xx9yj 8yw4ukdf( $I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, 1(24z;d3nqrfheo bx pwith unequal emfs of 2.00 V and 3.00 V, are connected as shown in (Fig(3ex 12foznd4hqr;b p . 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 capaci, l scedaa:m6o ad6 cyb980fn)tors, 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 whole n u30f/pwfge 2l 3a.wj3 xfkyd4etwork of (Fig. Below), calculate the voltayfa.3pfu03fj2 wx4/d w3lgekge across each capacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portize4t 0p90uskpon of a circuit is to be reduced from 4800 pF to 2900 pF. p0ep 4 9zku0st
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 a 2t3m gl)+n7 nlwn8kiqccidentally 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. t8sfoll; g/ r60(zhyyBelow).

  In (Fig. Below), if cnvg1*o d kata ,jk233$C_1=C_2=2C_3=22.6\mu F$, 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), supp 6x*n ;d 2)prl ox*xvfz2uw-/ cstrt)uose $C_1=C_2=2C_3=16.0\mu F$, 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 ,54nz qvx)k j(g6wpqb$V\,=\,78V$ 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 conn/p man;l p3c8iected as shown in (Fig. Below). ma3i/l cp;np8
(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-pck9z3 xe3.n abF capacitor hooked across a battery. It is desired to store three times as much znbxe3c ak3.9 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 a- g, (;gccjy n-e6i s* h7jwp8aw(uyfps a series combination they are connected to a battewf* jhjyia 6,( wcnpcyu7g-g8 sp-(e;ry 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 a 02 m dw i0fdj99t(evomg6-wsoften connected 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 potential to beivmaogsem w dd29f9tw6j0-0( 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), the total reewa ,7.4h - -kbdatbazsistance 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) hasi g 7i-as0hrl+ 97fuqo $R\,=\,6.7k\Omega$ 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 iniv ms+9msot7: (Fig. Below). Then a potential difference of 24 V is applied acrossm9s7:im vs+to 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 sensiti 3e iaugr1h,,uvity ghe3r u, ui1a,is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensi ;ljonrj.vz l0t( 9*o:oz*a3a xtaq4w tivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resiv yx4v7sd9 wr6y.3naystance 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 sensitivity of )y10h3*5nb lsex zlmn -: e3qyiklx+k $35k\Omega/V$ 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 1xsl,a59c n5 x eck8zb+.v5evj0 mA 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 i t):fsok * q 3vwwbha.o1(s7rlnternal 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 resisqe(gu 2i wwk7 0r4r(cptance 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 have to bbkp oy (jh-/v-+ y 3hdnhvp34rr 9we6xe in error by less thanpxor hp-9r vwh/ 3ej3d(h4- +6 kybvyn 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) 92s *mefk,8ss6d0nkln n3i h cis $35\Omega$, 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 0.2mu f.qu 13ej0a.-xxj-7 5i elzq it,jo5-V potential difference between two points on the human body. The resistanceal0ex jqji qz7f1 35t u moj..e-x-,ui 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 pa s ho+5o)nrqr mp08j3; dqut5roduce 50 W, 100 W, or 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually +oa8jt mhdq)r0pr5q s5;on 3uor 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 from an en*mi- -yfacr 0lectric outlet. Each of the wires connecting your apparatus to the 120-V source has ac0-y mn r*i-fa 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 wkmgy;p(n lg 7-0v s; uj:j,zfaho are connected to electrodes, such as an ECG. For example, suppose that the motj 7yg-vz gsl:k(n;m;a 0jup ,for 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 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 a w9e7kbuea a795 y lkhf/mo8 )zob4b* l$0.40-\mu F$ 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 designed to operp 1ha5y wmozj.qj ,+b*f+a i;zate 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 resistanbfs 4t *rf87sopy f1 p damg9j1+3hxd,ce 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” used to make measurementsxqtn,z0 4+e tb of resistance. The unknown resistancetq0ben,xtz +4 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.a+rz2l:t2 bx v4iod;2d3 w0mxw 5lk ok920 mm in diameter is placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Am23:w t 02b5 dk4 wok+2dillvxroax;zrms 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 t f6g)gnp.(zirm7v2 ccan be obtained by connecting four identical capacitv p .mfc6g)7(ni2rgzt ors, each having a capacitance C?

  The variable capacitance of an old radl/ rw5zdph 9(fio tuner consists of four plates connected together placed alternately between f/fw 9dzhr5(l pour 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 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 4093px 48eiybod/*p 6u*ucwh sw .8 V when 7.40 A is drawn from it and 47.3 V when 2.20 A is dr/ puwd poui*wce84x3 *yb s6h9awn. What are the emf and 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 thsdtsym8 .f8fc+wsihf0 t:6w,e $4.0-k\Omega$ 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 capacitor h4o+te-m / y4l ;6y3tfbuucy 6+kunnmf as 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(F ussl+z*/mtxy4 f;8vygs 6bu)ig. 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 V whe2rf+u ojpj,+j4fwx 8:fizu z5 n exposed to full sunlight. A solar panel that delivers close to 1.0 A of current atj8jfo: , 4fuz5r2jzpwxu+if+ 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 voltage of 12.0 h-q6/l -grnf ey i/oz5V, 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 (Fioc *03xn,h 4woar 0aocg. Below b). This neon lamp has a thnah0 c4oor,ox*3 ca0wreshold 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 the cara8k -w 8h-e 6w0)dy3przrr$20-\Omega$ 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. Below),;l:le.b2cu 6egxkcv v4 n r59r9prp0d 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 nrjq4pkr o z:12*p-nw the 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 shown in ibb-, cjq a v.w.cc0ymo:rq+mv-en: - (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeter reading, the valueyovinac b -:qwc0,j-bq +..erm-: vmc 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 ii hle*d-,n6m at 2.5 W and 3.0 V is operated by a 9.0-V battery. To light the bulb at its rated voltage and power, ae ii-hn,m6l d* resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$