Explain why birds can sit once07 7tyt8oci power lines safely, whereas leaning a metal ladder up againt8y7ti o7ecc0 st a power line to fetch a stuck kite is extremely dangerous.

Discuss the advantages and dj u alk49g(9qze8*z tl)zeea.isadvantages of Christmas tree lights connected in parallel versus thos) g4. 8aj9zzz q*9letk ule(eae connected in series.

If all you have is a 120-V line, would it be posz:3lo h(rl hz/sible to light several 6-V lamps without burning them (hl3horlz z/:out? How?

Two lightbulbs of resistanceue xt,53ec zw( $R_1$ and $R_2(R_2>R_1)$ are connected in series. Which is brighter? What if they are connected in parallel? Explain.

Household outlets are often double outlets. Are these connected inn b49myzjg)f5.bgl6e series or parallel? How do ybfj. ylmge45 b9)gzn6 ou know?

With two identical lightbulbs and two identical batteries, how would yyy dvbynlo ,6cj) 986eou arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume y8yyv,j de6 obln)96c the batteries have negligible internal resistance.)

If two identical resistors are connected in series to a q*u 7j /olqdy*battery, does the battery have to supply more power or less power than when only one of the resistors is connected?j7*dq /uy*lq o Explain.

You have a single 60-W bulb on in your room. How does the overallu*e) m*;i//c ea9*sg ur ljmhp resistance of your room’s electric circuit change when you turn on an esa g ;*/e/ic)m9uprmuj* l*hadditional 100-W bulb?

When applying Kirchhoff’s loop run 8udlw:2kta+)brk1l-42vkufl7c p )3mqq e ole (such as in Fig. Below), does the sign (or direction) of a battery’s emf depend on the direction of current through the battery? What about the terminal voltagee2plmd fl ar)knlku q23:k4- tb)1wcu 8o7v+q?

  Given the circuit shown in Fig. 19–36, use the l-fgzl -v:ibzg 46ds7words “increases,” “decreases,” or “stays the same” to complete tglg zfb-7s 4l:vd 6i-zhe 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 con mq,(5sow9g/5pn 92 dkengllpnected in parallel? Does it matter if the batteries are nearly identical or not i(,5 ogkgdqlm5enwns l /9 9p2pn either case?

Can the terminal voltage of a battery ever exceed its6wtz yh 845vzt emf? Explain.

Explain in detail how you could ox1 1/ve;u opqyq*b9ra(f;lk measure the internal resistance of a battery.

Compare and discuss thn5ij3 ni4igw(,w 0 fg:ej hlt9e formulas for resistors and for capacitors when connected in series and inwii0ef :i5t,gjl4 3 wj nh(ng9 parallel.

Suppose that three identical capacitors are connected to a battery. W5hr 2j scp*3pzr era9*ill they store more energy if connected3r5e*2jrs *az9rp chp in series or in parallel?

Why is it more dangerous to turn on an electric appliance when you hy6nztva* hyw ubq / ;8im:)f7are standing outside in bare feet than when you are ifzhmvt;u8*hb :qn7 6)yyai w/nside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphone. The changin )buyl s84eqe8g air pressure in a sound wave causes one plate of the capacitor C to move back and forth. Explain how e4u l8sqy8)e ba current of the same frequency as the sound wave is produced.

Design a circuit in which two different switches of the type show+. onl9v8 r.clys p4bpx:w :wv)yd/w zn in (Fig. Below) can be used to operatev).l48cb +/.w:y 9:lrywo sxvzpwpnd the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from the battery until the capacitor i6v) s;i t-iqd,.huej ks completely charged. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If not, where does the ex jik)q-6 vid;, ste.uhtra energy go?

What is the main differepqhl dy/n5v. *wr cq))nce between an analog voltmeter and an analog ammeter?

What would happen if you mistakenl/. (vfuikx0co4 g:kjiy used an ammeter where you needed to use a volfg c .vk:k/0uxj(4 iiotmeter?

Explain why an ideal a h-3 gtvrv*g1 nf)fqdzzj, :g*mmeter would have zero resistance and an ideal voltmeter infi - jzg*,vqn :dhf tz*3f1vg)grnite resistance.

A voltmeter connected s y-ccv *b(c2;lz(v,2n 4wns 4jpxwji across a resistor always reads less than the actual voltage across the resistor when the meter icslv 4vnicpcb-( jy(*z wx2 4,ns;2 jws not present. Explain.

A small battery-opera8ntb m4z)r5n 3w/iyit ted flashlight requires a single 1.5-V battery. The bulb is barely glowinnwb ym ti3)t458z/ nirg, but when you take the battery out and check it with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an internal resi 3ide+rn/gd*cstance 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 f4q(0*vt tzsz3r(wyu 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 asn 1 (o.wjweo7nx9w /gfciq;) $680-\Omega$, 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 havem6y50q lvxf2t a $6.0-V$ battery and you wish to apply a voltage of only $4.0\,V$. Given an unlimited supply of $1.0-\Omega$ resistors, how could you connect them so as to make a “voltage divider” that produces a $4.0-V$ output for a $6.0-V$ input?

  Three $240-\Omega$ resistors can be connected together in four different ways, making combinations of series and/or parallel circuits. What are these four ways, and what is the net resistance in each case?
The resistors can all be connected in series   $\Omega$
The resistors can all be connected in parallel.   $\Omega$
Two resistors in series can be placed in parallel with the third.   $\Omega$
Two resistors in parallel can be placed in series with the third.    $\Omega$

  A battery with an emf of )3hmv:47): ps ymkcpgmjz+ bm $12.0\,V$ 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 he xw,l,pos jesq+671in 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 0zw1wz6 18 +zxljl fnjto 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 revealsm vwhdobdigff0,zk 2*:*gp/ ) 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 of6ecg t q.ij5ms.;1hz e resistors shown in (Fig. Below). Answer qualitatively: e htq c65jz1 ;i.gse.m
(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 ii3.vlw6j6 jpv a7p(dgn (Fig. Below)? Each resistance(vvjgi3 lpwa6dp.6j7 has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connectedr3wg8fr/oi )m)jne +ya+7g- vg2w kka to a battery as shown in (Fig. Below). Qualitatively, what wa2/vrjofwgk) )+a 8ig mgr7-3 +neykhappens to
(a) the voltage drop across each of these resistors, $V_{left}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0 
(b) the current flow through each, $I_{left}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0 
(c) the terminal voltage of the battery, when the switch S is opened, after having been closed for a long time? terminal voltage  ----待选择----decreaseincrease0 
(d) If the emf of the battery is 15.0 V, what is its terminal voltage when the switch is closed if the internal resistance is $0.50\Omega$ and $R\,=\,5.5\Omega$?
$V_{terminal\,closed}$ =    V
(e) What is the terminal voltage when the switch is open? $V_{terminal\,closed}$ =    V

  A $2.8-k\Omega$ and a $2.1-k\Omega$ resistor are connected in parallel; this combination is connected in series with a $1.8-k\Omega$ resistor. If each resistor is rated at $\frac{1}{2}W$ (maximum without overheating), what is the maximum voltage that can be applied across the whole network?    V

  Calculate the current in the circuit of (Fig. Below) and show that the sum of algfqe3 g/g*9 lel the voltage changes around the circuit is zeg*93e/g gq lfero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal voltage4 khk:zq;n6u t of each battery in (Fig. Below). 18V battery =    V 12V battery =    V

  (a) What is the poteuc 42pkpzz w ;l 1a5 tm6:m+p*uf(eejnntial difference between points a and d in (Fig. Below a) (same circuitpa tm*2;4:u+nu lk(j mwp1zpec6fe5z 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 potential difkyo 5e;rc2*t hference between points a and b. Each resis ckye;o5rt 2h*tor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directr 79gyw bl+ t8zh8re5hions 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 battu or s2uwjad9mw.,/o( k+6o yg *ml)daery 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 th.4 vo1l 38k1zi gxbmgdnhx/ 7td*t62 sczcdf; e currents in each resistor shown in (Fig. Below). The d2t4xg zdtb;g*vx fh13lks7.nc6 c8iom1 /zd 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 internal resistance 0xu/ebp.s1fi :sgcl8 :e q 5qz $r\,=\,1.0\Omega$.
$I_1$ $\approx$    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 ibucc() ,fp t k32,j5odwv0 arin each resistor of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curr e +sq7t ybc;lcof;jk,w.:r8sents $I_1$,$I_2$, 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 currew r4r6lu:-adf 5qf b3mnt $I_1$ 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 connectptzyuz1:j .)n+j w-eqtmk1mvv87s(yed as shown in (Fig. Below). If eac u1pwjzn:t ky-v8)yt(+. me7m1 qsjzvh 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 capacitance 320rwb 5.i82n .gscxfw w80 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. Below),v dn.p9iiot mk02a-r4 calculate the voltage acrosn.vd4 tai omk 0pi9-r2s each capacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of a circuit is to be reduced from 4800 pF to 290q ob;:mk(te,mp.sy *st;tk6d0 p*tk;t:ym q m,kt( os;. 6sdpebF.
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 accid o*+:uoyg 2jp) cfgu(dentally 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 showh87zg0jg( fq2xc5 sj t 6yaw0qde(m7y(h/mnc n in (Fig. Below).

  In (Fig. Below), if 3.f*s ssoqq2dg1o;xo $C_1=C_2=2C_3=22.6\mu F$, 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), suppos )jkk/yho51 h1cmx1)gk ;pf,h 4 lsywpe $C_1=C_2=2C_3=16.0\mu F$, 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,xup0 st e3 d:j)nri8u $V\,=\,78V$ 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. B*krsobmt i2w s*b dyq/,l48-gelow).4 ,2yqmi- b*/*swokr sbgld8t
(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 across a battery. It is drbbqmi-2d t u-2hak76 esired to store three timesq-tukm-rbb6i d 2a7 2h as much energy in a combination of two capacitors by adding a single capacitor to this one.
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is connected in series with an unknown capad cq -8upjtt3-citance, and as a series combination they are connected to a battery with an emf of 25.0 Vtq8cjp3- -tdu . 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 in (Fig. Below). The l:55w51rfwn sy.ng zjqeads are said to be capacitively coupled. rg1y5 qw:wfn.z5 5n sjA 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), b y9m f(, p hmj*hylt7*m+tk)mthe total resistance is $15.0k\Omega$, and the battery’s emf is 24.0 V. If the time constant is measured to be $35.0\mu s$, calculate
(a) the total capacitance of the circuit    $ \times10^{-9 }\;F$
(b) the time it takes for the voltage across the resistor to reach 16.0 V after the switch is closed.    $ \times10^{-5 }\;s$

a
b

  The RC circuit of Fig. Belb.zvubpckz ,li/12 5b u60jc mow a (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 uncha7ma g8.ep0jz zrged capacitors are arranged as shown in (Fig. Below). Then a potential difference of 24 V is applied across the combination as showmgzz.ja pe780 n.
(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 sensitxi4h5 y9wrtxmxx1ix6iw0. ,mivit40xxi ,i ixm5t hxwxm9w.ry 61y is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivittmv,egi go:., e *o3iny of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resip2q) swsz+f ;b h0 t 30zj-p)znr9tbenaei2f ;stance 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 s0yj7lng x 61,hw (myydensitivity 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 scalehsj v*9o*v 8ha. 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 internal resistance is co2nrr nfxvh4uob3 0 v.*)6q iswnnected 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 resic l6taqpd)55 npz i:n+stance 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 voltm fp5mpd5r2ct17rgy 1weter of Example 19–15 have to be in error by lessrtcm5r p1157w fgpy2 d than 3%? $\approx$    k$\Omega$

  When the resistor R intruvt 6:hckw9y0/q g) (Fig. Below) is $35\Omega$, the high-resistance voltmeter reads 9.7 V. When R is replaced by a $9.0-k\Omega$ resistor, the voltmeter reading drops to 8.1 V. What are the emf and internal resistance of the battery?
r $\approx$    $\Omega$(retain one decimal places)
$\varepsilon$ $\approx$   V(retain one decimal places)

  Suppose that you wish to a sv ao2b/y-y8zpply a 0.25-V potential difference between two points on the human body. The resistance i-a/v 2s 8bzoyys 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 1,0e9e fo uh6d flr,;sd20 V. Such a bulb contains two filament ;du,eerofhl 690,dsf s that 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 outlc6oks9k sbh m*f :+k8ket. Each of the wires connecting your appark+ 9os * mk6h8kbs:ckfatus 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 hogm:dduxy 7 :,,/;bbsne9u g sespitals, particularly to patients who are connected to electrodes, such as an ECG. For example, suppose that the motor of a motorized bed shorndexy, :bs9/m ;eud bs7u gg:,ts 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 45a8+ ,vgwkwll5 -V battery expend to charge a $0.40-\mu F$ and a $0.60-\mu F$ capacitor fully when they are placed
(a) in parallel,    $ \times10^{-3 }\;J$
(b) in series?    $ \times10^{-4 }\;J$
(c) How much charge flowed from the battery in each case?
$Q_a$ =    $\mu C$
$Q_b$ $\approx$    $\mu C$(Round to the nearest integer)

  A heart pacemaker is designed to hu)imjzls/,tx9r11.*vee qs 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 resisa c wi2l/ily4s8l1 zb/tance 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 measurement::zq6kracl 9,e 2hid71x n n*vm;ad yjs of resistance. The unknown resistance to be measured, mn vh acil:*dn j:21,q9dkayrezx7; 6$R_x$, is placed in the circuit with accurately known resistances $R_1$ ,$R_2$, and $R_3$(Fig. Below). One of these, $R_3$, is a variable resistor which is adjusted so that when the switch is closed momentarily, the ammeter Ann Meter shows zero current flow.
(a) Determine $R_x$ in terms of $R_1$ ,$R_2$, and $R_3$.
(b) If a Wheatstone bridge is “balanced” when $R_1\,=\,630\Omega$,$R_2\,=\,972\Omega$, and $R_3\,=\,42.6\Omega$, what is the value of the unknown resistance?    $\Omega$

  An unknown length of platinum wire 0.920 mm in diameter is placed as th6kpa9- 7v 3 . ybagrga*mv5ktbe unknown resist v7pbr3m ka a.k* yb-ag5tv96gance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 have resistance of $38.0\Omega$ and $46.0\Omega$ respectively. Balance is achieved when $R_3$ is $3.48\Omega$ How long is the platinum wire?    m

What are the values of effective capacitance which can be obtained by conv 9 a/nhvaer+t/ en0jd0 :xxx*necting four identical capacitors, each having a capacit*9had/ / vtx0:r x+jex n0evanance C?

  The variable capacitance of an old radio tuner consists of four plates connectedal26 4jhbk9sas gge5. together placed alternately between four other plates, also connected toj ksg95.be gs l42ha6agether (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 7.40 A is drawn from,mm32yqrc:11m6d b) ymeus .ykgn:w v it and 47.3 V when 2.20 A is drawn. What are the emf and internal resistance of the battkn cb2m6 1,yqvm3 : wyrmg.y)due 1m:sery?
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 t dzo54da/s,ov;5 otv zhe $4.0-k\Omega$ 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 parallubfq (xm95 cw*el-plate 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), dc2d: -ktdk,v 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 0exret: 4+ xp6b.80 V when exposed to full sunlight. A s4 x+teerb p6:xolar panel that delivers 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 12.ejmw*-c1en n0:gc 8 pdko3+aj.nl pn4 0 V, but you need $V_T\,=\,3.0V$ for an experiment.
(a) Using the voltage divider shown in (Fig. Below), what should $R_2$ be if $R_1$ is $10.0\Omega$? $\approx$    $\Omega$(retain one decimal places)
(b) What will the terminal voltage $V_T$ be if you connect a load to the 3.0-V terminal, assuming the load has a resistance of $7.0\Omega$? $\approx$    V(retain one decimal places)

  The circuit shown in (Fig. Below a) uses a neon-filled t0-t 1iyeh h+zxube as in (Fig. Below b). This neon lamp has a threshold vxtyhe+0 hzi- 1oltage $V_0$ 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 b ;hif(0z,1s-7 viaoeuz6obrxt +se )the $20-\Omega$ 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. Beloxi 7 0*g ,(/x:qrhdw0ya tyufww), 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 shyv3x8* yqug.d own 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 (Fig. Below a) 4 qko+-;zd( c +l5ojh8 un c2uqemjfr-to measure a resistance R. If V is the voltmeter readiqr5+mfco4no 2 qz ; hul8u(jk-dj-ce+ng, 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.jndp,5h7n g+g5zj1sb 0 V is operated by a 9.0-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 vgg1n, h5+jz b7dnj s5palue should the resistor have?    $\Omega$