Explain why birds can sit on por9unqaeu:0r -v5f 1fa s14 yvgwer lines safely, whereas leaning a metal ladder up against a power line to fetch qfa1ev54gnv:10y-rsu ar9uf a stuck kite is extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree lights cd9b+it7 tb+f6* r*t k3bgyf . fvma7ijonnected in parallel versus those connected in sm a*t+.kj67 3f*tbf tr79d+bfgiivby eries.

If all you have is a 120-V line, would it be pos)(9bb o8i nnkzt-:xd tye1 v(psible to light several 6-V lamps without burning th9 ix:b e((bko1zt-pndy )vt8nem out? How?

Two lightbulbs of resistanc0j nmcgi3of7e6lf,2evz 8)o ie $R_1$ 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. Af6f jer6n2sh8 re these connected in series or parallel? How do y 6e2h8f fsj6nrou know?

With two identical lightbulbs and two identical batteries, how would y-ojs ,aqe-rzq ,h d86gou arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligible internal ress6- rzqehqaj -o d8,g,istance.)

If two identical resistors are connected in series to a batteryx3kzy*m (6 id61ildr.ovaj ,g, does the battery have to supply more power or less power than when only on.ia6xm l*di,j316 yor(z vgkde of the resistors is connected? Explain.

You have a single 60-W bulb onk1iq8 6 g cga7anc(2j4j, lvla in your room. How does the overall resistance of your room’s el7cnv a 6a4ag2lj 8 cg(k1jl,iqectric circuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (suh,wk ddzel3 ;ok6v zo.7rbn) 2ch as in Fig. Below), does the sign (or direction) of a battery’s emf depend on3. dr6oznekbh7 wok2)lv ,zd ; the direction of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “increa61 6mcvpxhhk, mw zh61ses,” “decreases,” or “st6,mzcp6 xh hh61vw1mkays 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 in series? For wai bhsxsn5 m066xd:8f hat use are they connected in parallel? Does it matter if the batteries are n bssi : 606x8mxf5dnhaearly identical or not in either case?

Can the terminal voltage of a batte/rerrf7y*rgx. dzf-a zg:w - +ry ever exceed its emf? Explain.

Explain in detail how you coul o1o)cqoeh24 nd measure the internal resistance of a battery.

Compare and discuss the fe+- bs5f,u8c.zatto m- eik kcn w,f3*ormulas for resistors and for capacitors when connected inf-m5z w-u*tsoci+8 t ke c,3fakn,eb. series and in parallel.

Suppose that three ide0 zo 5 tts*udek.mu4h.ntical capacitors are connected to a battery. Will they store oumdz h.50t*. uk4est more energy if connected in series or in parallel?

Why is it more dangerous to turn on an electric appliance when you are standi k*zbe s/sfbrm4d:.s7ng outside in bare feet than when you are inside wearing shoes with thick so:4*fs.sresdm7b zk b/ les?

(Fig. Below) is a diagram of a capacitor (or condenser) microphone. The changi js*fd-v;g( fkng air pressure in a sound wave causes one plate of the capacitor C to move baks f*fv -jdg(;ck and forth. Explain how a current of the same frequency as the sound wave is produced.

Design a circuit in which two different switchesmdz+ 58jxkd a5-3xh* kg2qjvm of the type shown in (Fig. Below) can be used to operate the same lightbulb from opposite si8x-jmkgh+ m ja3k*d2zv 55qdxdes of a room.

In an RC circuit, current flows from the battery until the capacitor is comus v8(2 m.ljfkpletely charged. Is the total energy supplied by the battery equal to th lm(8j f.sk2uve total energy stored by the capacitor? If not, where does the extra energy go?

What is the main difference between an analog voltmeter and an,qjyv)b8 v:4yxd,uu o analog ammeter?

What would happen if you mistakenly used an ammeter where you needed thls61 z jrnt pg00b7y:m7.olwo use a voltmet7zr0jhl ponl tsw6 ym.170g:ber?

Explain why an ideal ammeteyc.zm6 zw-t, jds*vizn92 3zo r would have zero resistance and an ideal voltmeter infini*-csyn 3v. 2zjzdmz9 z toi,6wte resistance.

A voltmeter connected across a rest skqq *rw2wyzmr49;-.5 dmhl a7zl3sistor always reads less than the actual voltage across the resistor when the meter is notz7s*95htyrmqlz lwswam ;q. k 34-2dr present. Explain.

A small battery-operated flashlight r,+h:mvesuy g1 equires a single 1.5-V battery. The bulb is barely glowing, but when you take the batteryyu,mh 1sg+v:e out and check it with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage f.e ;s(qs,skro or 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 resistfqq(i cr t0 uuk ,.r4c6w-mvt,ance 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 +eab6 :tcit/*td jld6$680-\Omega$, 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 a r7xc w/aap1(f$6.0-V$ 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 hk( jz-h5c 2ze: rlh)vof $12.0\,V$ 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 conn ) t6jh6.zh)wa*wwq avected 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 parallel to 1g/(zip; saold9lqa5a $110-V$ 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 cirw81 v v2crqe2ncuit reveals that a $480-\Omega$ resistor was inadvertently soldered in the place where a $320-\Omega$ resistor is needed. How can this be fixed without removing anything from the existing circuit?    $\Omega$

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

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

  Consider the network of resistors shown in (Fig. Below(lg*k(k*yjduqok kyq7 z tk7b+3fs ; )). Answer qualitatively: k+7y(kg *l7kqz;*u 3y s qt(o)jk fbdk
(a) What happens to the voltage across each resistor when the switch S is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(b) What happens to the current through each when the switch is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(c) What happens to the power output of the battery when the switch is closed?  ----待选择----increasedecrease 
(d) Let $R_1=R_2=R_3=R_4=125\Omega$ and $V\,=\,22.0\,V$. Determine the current through each resistor before and after closing the switch. Are your qualitative predictions confirmed? Notice that the current through each of the parallel resistors is half of the total current, within the limits of significant figures. $I_1$    A $I_3$    A $I_4$    A Notice that the current through each of the parallel resistors is one third of the total current, within the limits of significant figures.$I_1$    A $I_2$    A $I_3$    A $I_4$    A  ----待选择----YesNo 

  What is the net resistance of the circuit connected to the battery innh:vg oozh-s0x6p* )c (Fig. Below)? Each resistance has voh pg oh)x6:cn*0-sz $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) arpxq.weaw 6334 gb, tc a:grh9pe connected to a battery as shown in (Fig. Below). Qualitatively, what happeph t3qw3c.x :eg rabag 694wp,ns 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 5 + +:piuzy;8nidpueu; klp-dthe circuit of (Fig. Below) and show that the sum of all the voltage changes around the circuit is zu klnzp;+pedp;du5+ u: yi-i8ero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each battery in (Fig. Below). 18V eac) 4tpn0ap8 /lxla(j),jke battery    V 12V battery    V

  (a) What is the potential difference between points a and d in (Fig. Below av x:8flwhvzk(w30 -zb ) (same c xkzb3w- zv0wv8f: lh(ircuit as Fig. Below b, ), $V_{ad}$    V
(b) what is the terminal voltage of each battery?
80V battery    V
45V battery    V

a
b

  For the circuit shown in (Fig. Below), find the potl lbeh7n+. +w6kt xo5dential difference between points a and b. Eac.tl++blhd6 x5woe7nk h resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the curren 3 i,f4mhco:qqts 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 tultd+djdr3 (3h3s)iz o5 ba1d:ua j; vhat each battery has an internal resistance $r\,=\,1.2\Omega$.
$I_1$ $\approx$    A  ----待选择----leftright (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftright  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftright  (retain two decimal places)

  Determine the magnitudes and directions of the curna/ xs/m h9)aarents in each resistor shown i )n//xh9a msaan (Fig. Below). The batteries have emfs of $E_1\,=\,9.0V$ and $E_2\,=\,12.0V$ and the resistors have values of $R_1\,=\,25\Omega$,$R_2\,=\,18\Omega$, and $R_3\,=\,35\Omega$
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Repeat Problem 29, assuming each battery has inte2vxhej w3x7 u(rnal 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 resisz97bw* 5q:2ss(xgnfoonqsu 9gm mr9qy xl;(9tor of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currea.ivq:b);,b so.xabq nts $I_1$,$I_2$, 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 v:hxndb)2(ffc1c0x j aj 1u/b$I_1$ 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 2.00 V and 3.00 V, are con lb)g38 ju jj/94aa,h;m4y uu zmt .d;ldlgrg(nected as shown in (Fig. Below). If eacz(4ud9uj )gy;3;u, l/ bd.hlg r48ajjtgalmmh 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 capp5 yn62aitbm. 39 jsfjacitance 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 +x,wplm) aa1vf2er8t . Below), calculate the voltage acrospe 1v+2r8aw fax,l)t ms each capacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of a circuit oa4(u85;/i hn b3 uwume--h8qfb x cdlis to be reduced from 4800 pF to 2900 u3d-hql-f 5e 488 mwinu cbh/a(obxu;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 accidentally construbec;hi;d6h8pxs bt t7lcfes37)t)v: cted 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. Bhtubi80 gv9v89pcla4d0 vm 5r elow).

  In (Fig. Below), if ub: hn /n k4:.x8s,x8k,joirww 3 bqsu$C_1=C_2=2C_3=22.6\mu F$, 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), supposeod(8:5x,qca2 q u gtvz $C_1=C_2=2C_3=16.0\mu F$, 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,09ktnqv-s,h uw txc: p- ol;k7u/ jwt $V\,=\,78V$ and $C_1=C_2=2C_3=7.2\mu F$. How much energy is stored in the capacitor network?    $ \times10^{-2 }\;J$

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

Three conducting plates, each of area A, are connected as shown in (Fig. 5p t/+7jtgd83.xth ib krjfk7Below).7hrdt.58bi/ txpj7 k3j +kf gt
(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 capacitor hoo w;v)eozvbmu*1 ;dx5k ked across a battery. It is desired to store three times as much energy in a combination of two capacitor)*kvb; d 51e;uzowm vxs 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 connecteoy 12(y, +u3n9n gcadsith(a ad in series with an unknown capacitance, and as a series combination they are coya o3nh1t(i g+y c9(ada2 nsu,nnected 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 capacitance?    pF

  Electrocardiographs are often connected as shown+otf: fl k ir:7-zf1pf 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 poten +:f1pfif7k-ftr:zlotial 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), the total resisc adym)3y/3dz tance 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. /df wvlq(rmsoh294d (same as Fig. Below b) has $R\,=\,6.7k\Omega$ and $C\,=\,3.0\,\mu F$. The capacitor is at voltage $V_0$ at $t=0$. when the switch is closed. How long does it take the capacitor to discharge to 1.0% of its initial voltage?    $ \times10^{ -2}\;s$
a
b

  Two resistors and two uncharged capacitors are arranged as showw dlno wig,:z:v9a5j,n in (Fig. Below). Then a potential difference of 24 V is applied across the comb9o :ziad j: gl5,n,vwwination 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 thezeu40amoi0fiv;f9wwh:tu 8u i5(jz5 250-V scale if the meter sensitivity f9uhj vi w w5it(;zfmziou0 :58aeu 04is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensi-i5 g+ p8: .k1wtosnuvsvth;+fjy .nx tivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resi f dnbs8( rz s5-bx-v(ivf.mw9stance 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 sent+ban2xg(2v8byvd3 yqn 31f r sitivity 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 fliw2(4,q o b.jt ni,zeull 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 intps8jj; f8a,cnfj.dunw3zt 1 6ernal 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 resistanc vl +8niluohwb)*z s/;e 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 voltmer /(z8mcwc)q2q2f eqy ter of Example 19–15 have to be in error by less than 3%/ q wz(r q8qc2)yfmec2? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) x *zs/ypxt7*.v .inbmis $35\Omega$, 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 potential differencj(b ba5w6rh ivxm7 xfo1 )w5:ce between two points on the human )xwcj5 rmf7(o5ahi :1vx6bbw 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 7zs 1l9aj mrr8)9ap udW, 100 W, or 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually or in paraa d9a9l 781sz jumrpr)llel.
(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 acx(3 ,ou5e zdrun some apparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 120-V source has a resistance per unidoc 3(za u,5ext 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, particu ;6dfb frf/f*tnm*8 dblarly 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 drb/n *ff fm b;*8d6ftplace). 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 batte0d+qp3qssdg5 w)9t pnry 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 desig :ylnc6k5v; jh.pi;vhned 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 resistance isgp nyv0+:*bfrqkm)7z $950\Omega$
(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 v ozyj(c( c4hs/n7c6mcircuit” used to make measurements of reh (m/(jnzc6vco47cyssistance. 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 platin 2y-r5*umdqsu um wire 0.920 mm in diameter is placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Be sur2-5* dyqumlow). 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 cao d/ , ga,+r)syl:agzgpacitance which can be obtained by connecting four identical capag aos,dgz,l:/yra+g)citors, each having a capacitance C?

  The variable capacitance of a*eeec+6 yvew:nn 3nab3vp70 in old radio tuner consists of four plates connected together placed alternately between four other plates, also connected together (Fig. Below). Each plat6 e3v: n0 w bec3ny7nv+eepai*e is separated from its neighbor by 1.5 mm of air. One set of plates can move so that the area of overlap of each plate varies from $2.0cm^2$ to $9.5cm^2$
(a) Are these seven capacitors connected in series or in parallel?  ----待选择----parallelseries 
(b) Determine the range of capacitance values. from    pF to    pF

  A battery produces 40.8 V when 7.40 A is drawn from mhi 78 c qp/dch4rf4o0it and 47.3 V when 2.20 A is drawn. What are the emf andihfq 40 8hop/cd4r7mc 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 the u :yx/ vef/rb9zu(sl )$4.0-k\Omega$ 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-playkq ;26cb-u/zw1teel te capacitor has capacitance $C_0$. If two identically sized dielectric slabs of dielectric constants $K_1$ and $K_2$ are inserted as shown in Fig. 19–64, what is the new capacitance? [Hint: treat this as two capacitors in combination.]

  For the circuit shown in(Fiveu j+;/ w(ful(jf s4s7 :htxfg. 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 when exposed tc0qz2 4uye211junds 1msv4 vl bp z*hm,8ial 8o full sunlight. A solar panel that deliv v c2 01pm1yd ize1z4n*ula8 hulvssqmbj2,84 ers close to 1.0 A of current at an emf of 120 V to an external load is needed.
How many cells will you need to create the panel?    cells
How big a panel will you need, and how should you connect the cells to one another?    $m^2$
How can you optimize the output of your solar panel?    banks of    cells in series per bank, with the banks in  ----待选择----parallelseries  always have the panel ----待选择---- pointedturned  directly at the sun。

  A power supply has a fixed output voltage of /pvnxtig59v1 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 uz..hd5 zcafvu(wf7ys26y sw e5y7 (9jruxi8 a neon-filled tube as in (Fig. Below b). This neon lamp has a tfwj.irf5( (uu287u y v sxy6cz.75zde9wsa hyhreshold 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 pzp z:m0h-rxe*8-t u rthe $20-\Omega$ 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 (Fikv04 9usy*d2q w*j .ev5 gveeo;.uror g. 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 resisif lw**-qg ufsbg*1 1rtance of 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 connecdmr 5d*zd :. ,z42 l2:d:wsuvsthoim ated as shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter rea.rstz5uwdosh: m 2v:4d*lzdm:2 a,idding, and I is the ammeter reading, the value of R will not quite be $V/I$ (as in Ohm’s law) because some of the current actually goes through the voltmeter. Show that the actual value of R is given by
$\frac{1}{R}=\frac{I}{V}-\frac{1}{R_\mathrm{V}}$,
where $R_V$ is the voltmeter resistance. Note that $R\approx V/I\quad\mathrm{if}\quad R_\mathrm{V}\gg R$ .
(b) A voltmeter and an ammeter can also be connected as shown in (Fig. Below b) to measure a resistance R. Show in this case that
$R=\frac{V}{I}-R_\mathrm{A},$
where V and I are the voltmeter and ammeter readings and $R_A$ is the resistance of the ammeter. Note that $R_\mathrm{A}\quad\mathrm{if}\quad R\approx V/I\quad\mathrm{if}\quad
R_\mathrm{A}\ll R.$

  A flash lightbulb rated at 2.5 W and 3.0 V is operated by a 9.0-V battery. To l6q2 z q(gon 3giqw)+7 i6;nnalc5adnjight the bulb at its rated voltage and power, a resistor R is connected in series as shown 7cg6nqqlon;zn d3ani w+ai)5jq(26 gin (Fig. Below). What value should the resistor have?    $\Omega$