Explain why birds can sit on power lines safely, whereas leanizp5k0+qy r9akng a metal ladder up against a power line to fetch a stuck kite is extremely dangero+0qk 95razkpyus.

Discuss the advantages and disadvantages ota k)dgax+93ceur (,z f Christmas tree lights connected in puzcxae9dar+), (g 3tkarallel versus those connected in series.

If all you have is a 120-V line, would it sn 0 04ilcw.dlbe possible to light several 6-V lamps without buriwln0lcs d04. ning them out? How?

Two lightbulbs of resistance 4fuq1u2jwmi 2:8cjet $R_1$ and $R_2(R_2>R_1)$ are connected in series. Which is brighter? What if they are connected in parallel? Explain.

Household outlets ar0hvi ab(xp594lwl5 rv j-wq*e x :8kove often double outlets. Are these connected in series or parallel? How j xrh4v iwvel5o*v0-(x 8:kq l5aw9pbdo you know?

With two identical lightbulbs and two identiig- -ira)* 7fkwv1 jg,gv*ypical batteries, how would you arrange the bulbs and batteries in a circuit to get the maximum poss gwfa-jkv-gg,ir*)7 i1ivp * yible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in series to a battery, does vknf6mo(z)*fe*da 9j the battery have to supply more power or less power tha)v k6* ofen f*9amjzd(n when only one of the resistors is connected? Explain.

You have a single 60-W bulb on in you *.01z,jpystpg-xk nfr room. How does the overall resistance of your room’s elen0jypt pfs*x.z 1k-g,ctric circuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as ,b 1)+x egrx*q,8ery: bw x pebbv6af(in Fig. Below), does the sign (or direction) ofab1wv*x),r bxgbreb(,:f6e q pe+ xy8 a battery’s emf depend on the direction of current through the battery? What about the terminal voltage?

  Given the circuit shown h(sms7( whc)i in Fig. 19–36, use the words “increases,” “decreases,” orih(7(c) smhsw “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 in series? For what use are e.j fmcwq1 3t,,nqg/kthey connected in p , qkwnq3ec ./m,tjfg1arallel? Does it matter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever exceed its emf? Ex +-lym yqm69lkplain.

Explain in detail how you could measure the internal resistance of a battery.fhos8c:1vd-q4 x g6(e:c mumd

Compare and discuss the formulas for resistor6.bwu 7q *dgfx-u fe-zs and for capacitors when connected in series and in *wbug.fdq7-u6x e -fzparallel.

Suppose that three identical capacitors are connected to a battery. Will t./a/u m5a(tvbilmr3x1e 7i hohey store more energy if connected in series or m htax/el a1rou 7mvi(.bi/35 in parallel?

Why is it more dangerous to turn on an electric appliance when you vi 73/ qc9 fzg8vdw*mc/jd3a xod.pn 4are standing outside in bare feeg4z*w dx8vjmacdd3 9c73/pi.vqnf /ot than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or u50u15o dqyu ccki ;xp0yi0e,condenser) microphone. The changing air pressure in a sound wave causes one platq 55ic;0ud0ie1uyp,0uc kx o ye 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 differentvj9/x6g5ark o switches of the type shown in (Fig. Below) can be used to operate the same lightbulb from opposite sides of a roo/a v9gxkj5 o6rm.

In an RC circuit, current flows from th5 mv17q7 q9ru 6evf+kn asugt7e battery until the capacitor is completely charged. Is the total energy supplied u9u 5 vmf7nvrq77st6+ gqka1eby the battery equal to the total energy stored by the capacitor? If not, where does the extra energy go?

What is the main difference betweer;z spifcern1x w.*u095wqz 5n an analog voltmeter and an analog ammeter?

What would happen if you mistakenly used an ammeter where yo-mc8zm2 2mdm-,xb h om;;aszzu needed to use a volt;mxhzmz -ma;8zb,2c d-2om msmeter?

Explain why an ideal ammeter would have i)oiiwugag.5g ,.m)a us) phcut )+*j 8;rlumzero resistance and an ideal voltmeter infinite resil,t 5mi iam wu)uog) gsc.a)8).ijhugp*u+;r stance.

A voltmeter connected across a resistor always re: +94nze . at(twnjrnfjl6ep7ads less than the actual voltage across th7.j6 wrjan:p ( nee+nt4t9zf le resistor when the meter is not present. Explain.

A small battery-operated flashlight requires a single 1.5-V battery. The bu)pita ,2(fwyc3 p rcf46wq 3ymlb is barely glowing, but when you take the battery out and check it with i,3my4rqf2c )wc y pa(pf3w6ta voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the termin9(rxmw7q:cvnq ;v n,tm4p ik3 mdi8 9pal voltage 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 yjhyhj./2e )2kem- o2 zdt8da$12.0-V$ 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 zywzw ,,r f:dh5+lci* a $680-\Omega$, a $940-\Omega$ and a $1.20-k\Omega$ resistor. What is
(a) the maximum,    $\Omega$
(b) the minimum resistance you can obtain by combining these?    $\Omega$

Suppose that you have s6jsu elbq)vnc3)r tf. 6oi 43a $6.0-V$ 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 o:54 cr)cy z3aqxs6avef $12.0\,V$ shows a terminal voltage of $11.8\,V$ when operating in a circuit with two lightbulbs rated at $3.0\,W$ (at $12.0\,V$) which are connected in parallel. What is the battery’s internal resistance?    $\Omega$

  Eight identical lights are connected in series acrosr*h: s4e,gfe gh (tig+s 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 tmyco j9)0mqf /re3w4yo a $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?
$V_R $ =    $\Omega$
firaction wasted =   

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

  A close inspection of an electric circuit reveals that a v4.zahma4we* $480-\Omega$ 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 shoy 1 v; wfu (6;.g: -imknzsqzqp*3xqlown in (Fig. Below). Answer qualitatively: mi-; 3 z q*qqksx(ouzn61yg;lf:w .pv
(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 connehyo 9cyv8/ gm-cted to the battery in (Fig. Below)? Each resistan/9o yyv-mc 8ghce has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as sdy.vpo8 559 ml*bmxld hown in (Fig. Below). Qualpyxdd85 .*mllm b9vo5 itatively, 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) anezy zir+ghq.r2 . .*zqd show that the sum of all the voltage changes around the circuit is zero. ry2z*zr. q .eq +.hzig
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal voltage of each battery in (Fig. Below). 18V batte9da hw4q8f4331ez1 4 twcqj v(brv kbxry =    V 12V battery =    V

  (a) What is the potential difference between points a and d in (Fig. Below atupepx(ujoyfd,.oh1vp1 fvz-;2 4o3 ) (same circuit as Fig. Belowf.to-p jpvodu, 2 f(voz x31;4 phue1y 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 potentiaadx.fo*5xvz:nnzrl 47k + p)ul difference between points a and bzva nx7l5fx)n dop+4zk:u* .r. Each resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directc2sk7 )laq,+3781kirp vhw tlja( nzsions 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 internal 9 b0eusl51gwf u)q7vdt03tvda n8vi6 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 1qlt m9mkw r(d0(hk xfz)3 9xhshown in (Fig. Below). The batteriesh0 k)f9k mq9t1mx( lxh3zr( wd 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, assumzql4+: u 1wlz d+yi-rsing each battery 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 resistor of (Fig. Belqr++*hac-- vn .sai.g0 )c nf *dxqynsow).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the cu4*kdjgc .lc 7mrrents $I_1$,$I_2$, 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 n9mzod.9+m lvc q.w f5$I_1$ 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, arecwmur1 4 )9-)1qf;ekhyy jbrv connected as shown in (Fig. Below). If each internal resistcw);-y)1v419ykm rf he qubr jance 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 capacitance 3200 pF, 7500 p .qfaxdl iw/c; 8wk+5aF, 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 bupk0 st/qfl:m3u -9r-f e;h0f nf+oqnetwork of (Fig. Below), calculate the voltage across each capacb tl /mq+foh0f-;sqr3 -9 unkffpeu0 :itor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of a circuitbty 3((lje;kvgs;d )7 e e.ep rg/5jpj is to be reduced from 4800 pF to 2900 pF.j(yrsjk ) 75( g/b3e.dgvee ;jeppt;l
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 constructed usingomba,j84r 4qg 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 ci8mcx4a7 i c3omrcuit shown in (Fig. Below).

  In (Fig. Below), if )s;mjn 3hxue-y8 u9o s$C_1=C_2=2C_3=22.6\mu F$, 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), supposoc ;lc5 maxua 01rg*kut1/ b.1 a4zjsoe $C_1=C_2=2C_3=16.0\mu F$, 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), letysjanbg a3e()3, n t,n $V\,=\,78V$ 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 plateo plx(gjn+zd.o/ 3/p xgsmv-+s, each of area A, are connected as shown in (Fig. Below). .-og+/zp3lop sm+v x(jng / xd
(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 hooked-ffu j m/(ztp3b;h) fv across a battery. It is desired to store three times as much energy in a combination of two capacitors by adding a single ca-tfvpf3z ;u)(/ bfm hjpacitor 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 capacitane9p ,t/ k;f:wkmgs.ae ce, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 185-pF captkg :/w9 ks,p eaefm;.acitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often connected as shown in (Fig. Below).ll: kt;iwviw1s 2l;a9.xs.)qe e yml;5 pk.jz The leads are said to be capacitively coupled. .iq.:l.ji9e2e1mk sak;;; 5yxw l tsz) vwllpA time constant of 3.0 s is typical and allows rapid changes in potential to be recorded accurately. If $C\,=\,3.0\mu F$, what value must R have? [Hint: consider each leg as a separate circuit.]    $ \times10^{6 }\;\Omega$

  In Fig. Below a (same as Fig. Below b), the total resis9m8rbllhe*ffk7za;0i j xde5 )g,sb9 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 (same as Fig.j/fqcf+7*v:0*x mlsl cyntq+bus l-1 Below b) has $R\,=\,6.7k\Omega$ and $C\,=\,3.0\,\mu F$. The capacitor is at voltage $V_0$ at $t=0$. when the switch is closed. How long does it take the capacitor to discharge to 1.0% of its initial voltage?    $ \times10^{ -2}\;s$
a
b

  Two resistors and two uncharged capacitors are arranged as shown in u-prik +(7 8lhsz:gti(Fig. Below). i+khpgil us7rz : -t(8Then a potential difference of 24 V is applied across the combination as shown.
(a) What is the potential at point a with switch S open? (Let $V=0$ at the negative terminal of the source.)    V
(b) What is the potential at point b with the switch open?    V
(c) When the switch is closed, what is the final potential of point b?    V
(d) How much charge flows through the switch S after it is closed?    $\mu F$

  What is the resistance of a voltmeter on the 250-V scale if thlqorj8i ;i.4 jevcxvt) ,.bg 0e meter sensitivity icbx;0 i4g 8. vjj qlr.v,oite)s $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensiti(dc7 m-qn vjf+vity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal b,7v 3c3tmtfhresistance 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 an3.fahat yj m4z ki0pwa48 mig,*9+op sensitivity 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. n4bc 0 )n6 odlvl.m8esj5+f q11uczlpIt 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 internal resistance is co9jyq o+xsb 7 )5sod5nknnected 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 resistanhn e;11g m 5n*t/xc znfyzi.l9ce 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 thm /d xz;yert9 i374z 9wuh2m;u+g frqce voltmeter of Example 19–15 have to be in error by less than 3%? u/wzd 3uc iqx+zy4gm2 r r;7mf9;9eth $\approx$    k$\Omega$

  When the resistor R in (Fig. l 8cye2(uo g6lxt9tn,** ffqtBelow) 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 pot/ tds*7wwtpq3p+a/w c ential difference between two points on the human body. The resistance t/3a/ w*pwsdp+7c wqtis about $2000\Omega$, and you only have a 9.0-V battery. How can you connect up one or more resistors to produce the desired voltage?    k$\Omega$

  A three-way lightbulb can produce 50 W, 100 W, or 150 W, at 120 V. Such a b 0v 6thez--e0fn3d9yvlvo (dxulb contains two filaments thavyvev0f3l dxn69 -t-0zh(edot can be connected to the 120 V individually or in parallel.
(a) Describe how the connections to the two filaments are made to give each of the three wattages.
50 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
100 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
150 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
(b) What must be the resistance of each filament?
$R_{50W}$    $\Omega$
$R_{100W}$    $\Omega$

  Suppose you want to run some apparatus that is 95 m from an electric rn*6aex)xj on n9 8dr.to0kp,outlet. Each of the wires connet 8k9onepdxj* r oax6r.,n)0ncting your apparatus to the 120-V source has a resistance per unit length of $0.0065\Omega/m$. If your apparatus draws 3.0 A, what will be the voltage drop across the connecting wires and what voltage will be applied to your apparatus?
$V_{wires}$    V
the voltage applied to the apparatus is $\approx$    V(Round to the nearest integer)

  Electricity can be a hazard in hospitalk16kno7lsz(it7 k ma,s, particularly 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, k1 mzk ,sl(67ko7nita 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 ba9b/-rp:a 73lmpnvkj qk qa ;lhby*d60 ttery 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 designed to operat1+; pbdqhv e)qe 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 bod*,l )qoic4e qzy resistance 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 circu 6m )/s3kxzsxh2v+ tmtit” used to make measurements of resistance. The unknown resistance z)hm2+sx / tx3tvks 6mto 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 place 7apls*mi 4pbbk04; t*hi6nftd as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 have resist6k* ls7ttfa;mi 0np i 4bbph4*ance 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 obtainkj *u9fl 1r. p1dao6bced by connecting four identical capacitors, each having a c r*6du1pkf .1ao ljb9capacitance C?

  The variable capacitance of an old radio tuner consists of four pla 2pwlpd *cku4sw:1a;ba9kv9l tes connected together placed alternately between fw4ac1p ka*dk9 9lu 2vsb:;wplour 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 40.8 V when 7.4o8gz8lq r+mr, s2a te,0 A is drawn from it and 47.3 V when 2.20 A is drawn. What are that2rsg8r+l,8zom qe ,e 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 thesw *-k)cvi1s-k c wi:s $4.0-k\Omega$ 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 itm hb2i: 2 ke(kwu1f)capacitor has capacitance $C_0$. If two identically sized dielectric slabs of dielectric constants $K_1$ and $K_2$ are inserted as shown in Fig. 19–64, what is the new capacitance? [Hint: treat this as two capacitors in combination.]

  For the circuit shown in(Fig. Below), deterl1ftf/ 7l 8dnsx3z2m amine
(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, hlxd/e; c3 u;7rg 2+) xcmpkptzas an output of 350 mA at 0.80 V when exposed to full sunlight. A solar panel that delivers clo c+p)gx/x7ct;2pe kz mld ;ru3se 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 12.0 V, but you needp8o ghg -;u1z ieg*2+abg7ivj.au* jg $V_T\,=\,3.0V$ 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. Bomydvw34vxe 5m03rg:3 (uzcx elow a) uses a neon-filled tube as in (Fig. Below b). This neon lamp has a thresholdr mgc:vue3xom5wxz 03y3 vd 4( 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 th5,l5 m1 b5 w.bemmwwwye $20-\Omega$ 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 .,g7.nc,z w lcjh 9kbwin (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 circuit shown in (Fig. Below)3 r; ; uelfow./f4yamm? $R_{eq}$ $\approx$    $\Omega$(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 conebnoc uqj )t( y6t4:3j7z 3udhnected as shown in (Fig. Below a) to measure a:()dnt63y4zce boutj7 q ju3 h resistance R. If V is the voltmeter reading, and I is the ammeter reading, the value of R will not quite be $V/I$ (as in Ohm’s law) because some of the current actually goes through the voltmeter. Show that the actual value of R is given by
$\frac{1}{R}=\frac{I}{V}-\frac{1}{R_\mathrm{V}}$,
where $R_V$ is the voltmeter resistance. Note that $R\approx V/I\quad\mathrm{if}\quad R_\mathrm{V}\gg R$ .
(b) A voltmeter and an ammeter can also be connected as shown in (Fig. Below b) to measure a resistance R. Show in this case that
$R=\frac{V}{I}-R_\mathrm{A},$
where V and I are the voltmeter and ammeter readings and $R_A$ is the resistance of the ammeter. Note that $R_\mathrm{A}\quad\mathrm{if}\quad R\approx V/I\quad\mathrm{if}\quad
R_\mathrm{A}\ll R.$

  A flash lightbulb rated at 2.5 W and 3.0 V is operated by a 9.kj/ hwf ux,+q)0-V battery. To light the bulb at its rated voltage and power, a resistor R is connected in series as shown in (Fig. Below). What vfj w /khq+,ux)alue should the resistor have?    $\Omega$