Explain why birds can sit on poweyv nnfe433. qo 1vrsa-r lines safely, whereas leaning a metal ladder up against a power line to fetch a stuck kite is ext3nv 3.n- sav1fryo4qe remely dangerous.

Discuss the advantages and disadvantages of Christmas tree lights connec);v ) uon*(a4togsvoqted in parallel versus those connected in s4uvqs (;o ngaovto*))eries.

If all you have is a 120-V line, would it b.zpl3eh 3mqlpxl:g7c;,nt . ve possible to light several 6-V lamps withoupm.g .c,3z tl:7xl neqh; 3vplt burning them out? How?

Two lightbulbs of resi/utqazl- fn:0 dh1, yg kr/d62ztfggja7b a (6stance $R_1$ 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 thez4 jpv6d x-ug psqm85y z..ch;se connected in series or parallel? How do qp-cypdvjz46.8 zs.h; x5mug you know?

With two identical lightbulbs and twvev50zuw6i6v- vzyj 0 c3heq-o identical batteries, how would you arrange the bulbs and batteries in a czvu-vcz6 e iyh036q50j evvw-ircuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in /u(o f.z e3rms-, ghqzseries to a battery, does the battery have to supply more power or less power than when only one of the resistorq m ush(eo/-gfzr3z.,s is connected? Explain.

You have a single 60-W bulb on in your room. How does the overall reir+ iz0 da.q 4og mybs2c 1ma-50hybr9sistance of your room’s electric circuit change when you turn o+.y49 d0h ybqc bim-2r1 agos5rmz0ain an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below), does the sign (or jbr izls.z*(/;jlr937khig zlgf/3 ndirection) of a battery’s emf depend on the direction of current through the battery? What about the terminal volj79; *zrz z l3r.f(/iki l/sbgljn 3hgtage?

  Given the circuit shown in Fig. 19–363 mkk42crgv65x 6hp/y t1 emcd, use the words “increases,” “decreases,” or “sttkx6 dvp yc3he2c5grmk1 4 6/mays 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 whu o1 zk3uidr, o)ta,)vat use are they connected in parallel? Douou1a t)v3do , zr,)kies it matter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever exc5gk2 c1z qp5qheed its emf? Explain.

Explain in detail how you n(j2ibfgx:t kry4,vc c)ux h*3pu;w 3 could measure the internal resistance of a battery.

Compare and discuss the formulas for resistors and fp1k )r1lr mrb.m56g3zgwi8 jlor capacitors when connected in serbp1rg5.3 ml l6)rgzjimk18w ries and in parallel.

Suppose that three identical capacitors are connected to a battery. Wieeqr8zg0 )+chqqsq : ,ll they store moqe :c qqeqz+g rs8h0),re energy if connected in series or in parallel?

Why is it more dangerous to turn on an electric appliance when you ds+*88gng pnj are standing outside in bare feet than when you are inside wearing sh+ 8dpn *sn8ggjoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or n5ub+tl2 r ucy8mn:6econdenser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to uc 2nmby 5:tnr 68lu+emove back and forth. Explain how a current of the same frequency as the sound wave is produced.

Design a circuit in which two different swj)0 -6jur.0kq cd qbkfitches of the type shown in (Fig. Below) f.)q kcrbd u-0j6qjk0can be used to operate the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from thejnlo0kxa84r:v f 23gu battery until the capacitor is completely charged. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If l4uj rk 2xa0fnvo 3g:8not, where does the extra energy go?

What is the main difference betweeh+3h3yr x0xkj n an analog voltmeter and an analog ammeter?

What would happen if you mistakenly used an ammeter where you needed to use f.h6e4 5cbk;xbba)stkbk z+ ,l;p0v ua voltmeter?; .efk b6ub4vbx c;bhzs5k t,+ al)kp0

Explain why an ideal ammete/:ym.it59(di qcfr nkr would have zero resistance and an ideal voltmeter infinite resista itcqk:5idfy9 mr(. n/nce.

A voltmeter connected acrqln znum3og ik64 w,,ox08pr;oss a resistor always reads less than the actual voltage across the resistor when the meter is not presen, kx3piq6n ;,40lo ozwmur8gn t. Explain.

A small battery-operated flashlight requires bc .+tmkbev c.33b c2ja single 1.5-V battery. The bulb is barely glowing, but when you take the battery out and check it with .3mjc bck bctb2+e.v 3a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an i/y6 c6v9tz(-rm kx mdhacdv+5 nternal 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 resisu0mkvqpv-37u 4 e/4tp 6jpoumtance 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 6qz4u j 0gg027ilazlo$680-\Omega$, 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 fx;cwwg:7 f i:rh/uj 1a $6.0-V$ 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 o nxl0,q:5;nqkvmk) k $12.0\,V$ 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 k)(d.i/;vchpt d+ozd 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 conne1b jk5r*w o/i:s e1ewicted in parallel to a $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?$V_R $    $\Omega$   

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

  A close inspection of an electric circuit revealhg7jedaa3 3jfz +e27zs 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 ofvpz -h5 re(tqqbj 7/p: resistors shown in (Fig. Below). Answer qualitatively: eq:7 tr( /v-b5pjpqzh
(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 con hv ).de/zmm9tnected to the battery in (Fig. Below)? Each resvtd.9 m/)em hzistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are c 3p +wbw65w*qkm1gr/wt +f dnsonnected to a battery as shown in (Fig. Below). Qualitatively, what happe rgq1ps5 +w3 6*tmkb/fwwdn+wns 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.,40: to:xj hq qpuf7uk Below) and show that the sum of all the voltage changes around thqhqu :of4x tp7 0k,u:je circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltag-ktun(7 cg/d5qhua 9 u9 a:ehae of each battery in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the poter6 bna9 44mwmvntial difference between points a and d in (Fig. Below a) (same circuit amm46 wanv b49rs 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. Bqrygt92d t2wr s+z 9e8elow), find the potential difference between points a and tzs2r 992g eqrdy+w 8tb. Each resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the currentk6q y+i2mpiryw *.dor )odn )73 yfjm3s 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,y8lflh1fc y0 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 currents in each resistor shk/d); fha;,o;:wikklcgjep3q wf9)pown in (Fig. Below). The batteries havgd;3i/f: ;wpk,k qfea kjp w) ;oc)lh9e 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 ba*bo fq5i5n01dz 3dibr ttery 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 F) e1jw94g wjhgig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currentso(u ood;j6xqix1zmx 8ce9/g 4 $I_1$,$I_2$, 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 curren ,)8yv;xj yuq gey(xt*t $I_1$ 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 connected3h2gz+ fa e lq9pr5 x-to1ie8lwy+ ka2 as shown ihl e2gpw9ei8a+yat+5kx 132l z q-orfn (Fig. Below). If each internal resistance is $r\,=\,0.100\Omega$ and $R\,=\,4.00\Omega$, what is the voltage across the resistor R? $V_R$ $\approx$    V (retain two decimal places)

  (a) Six $4.7-\mu F$ capacitors are connected in parallel. What is the equivalent capacitance? $C_{eq}$ =    $\mu F$
(b) What is their equivalent capacitance if connected in series? $C_{eq}$ =    $\mu F$

  You have three capacitorsdwx,*q: 7 r9k9s fcjjy, of capacitance 3200 pF, 7500 pF, and $0.0100\mu F$ . What maximum and minimum capacitance can you form from these? How do you make the connection in each case?
$C_{max}$ =    $ \times10^{-8 }\;F$ in  ----待选择----parallelseries 
$C_{min}$ =    $ \times10^{-9 }\;F$ in  ----待选择----parallelseries 

  A $3.00-\mu F$ and a $4.00-\mu F$ capacitor are connected in series, and this combination is connected in parallel with a $2.00-\mu F$ capacitor (see Fig. Below). What is the net capacitance? $C_{eq}$ =    $\mu F$

  If 26.0 V is applied across the whc:l pt6::ocvtcco ;dwv qip +v9 **fo9ole network of (Fig. Below), calculate the voltage across each capacitoc:o*6i: qc p ttdvco;o9: p*lf+ vvcw9r.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a pmj b rwi7 4 vpd(zmdm35gk80;jortion of a circuit is to be reduced from 4800 pF to 2900 pF. jgzm (;0d b45 rvwm87mkd3pji
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 2vtw4xmqlo(m- uwrj2it v)7(accidentally 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 cg-+iy1 hx1brhbap -w 3ircuit shown in (Fig. Below).

  In (Fig. Below), if 2w m pjbgm-)u)-xwwk.jf) )zxhs.q7w $C_1=C_2=2C_3=22.6\mu F$, 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), supqf1xcqo dv 24/pose $C_1=C_2=2C_3=16.0\mu F$, 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), let8fj nzk c*:e*g $V\,=\,78V$ 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 (Fig8e 5inb3 qiy8fd4tit: . Below). 3fi8beqdnt i8yit4:5
(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 hool+p6+ yvs h;k gk.xs)in+ud/lked across a battery. It is desired to store three times as much energy in a combinatioi.6n +vksg/huxkp dl;)+y+s ln 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 ecs1gn:r/m+kcapacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 185-pF capacitor 1 /nek:gms+rc stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often connected as shown iz jolfn:6as 33v1 w0ern (Fig. Below). The leads are said to be capazvol1fe 3w60r 3njs:acitively coupled. A 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 Fiwo+kprk. ;+dqy o+f- mg. Below b), the total resistance is $15.0k\Omega$, and the battery’s emf is 24.0 V. If the time constant is measured to be $35.0\mu s$, calculate
(a) the total capacitance of the circuit    $ \times10^{-9 }\;F$
(b) the time it takes for the voltage across the resistor to reach 16.0 V after the switch is closed.    $ \times10^{-5 }\;s$

a
b

  The RC circuit of Fig. Below a (same as Fig. Below b) ha8* ceatk5hyc+*iyf5gd-ahaung w3 v ;(3,nv x s $R\,=\,6.7k\Omega$ 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 arrangp.l9kmqjujo(z; b l(1 ed as shown in (Fig. Below). Then a potential difference of 24 V is applied across the combination as showj ;km(1. (9qbljp lzuon.
(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 voltmet,yjmgq x76m9per on the 250-V scale if the meter sensitivity i, 69g7ymmqpj xs $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivity of3ogh28 na *yoeqxas 4 ,ozw.-o $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resistance ofpd1pys 2 xgx360 cc/ly $30\Omega$ and deflects full scale for a $50-\mu A$ current. Describe how to use this galvanometer to make
(a) an ammeter to read currents up to 30 A,    $ \times10^{-5 }\;\Omega$
(b) a voltmeter to give a full-scale deflection of 250 V.    $ \times10^{6 }\;\Omega$

  A galvanometer has a sensitivity of ; m9rnc5e1vfkuy 8(rpwpp n4 ($35k\Omega/V$ 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. Itq3ya1; /acq ekg7f1t1vvij-e w: zm /w 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 connec/i* -i;*ywi 3twhpg:n en a, oj)rxel+ted 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 resist/ye//y;ks6 i-y nk gahance 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 shouwkhu0 4c ft 4 (+gmx(j:vz(qfyld the voltmeter of Example 19–15 have to be in error (w ux4y(f: (z 4jk0cmg+fqthv by less than 3%? $\approx$    k$\Omega$

  When the resistor R in (F*nc3v* zn+zy eme-ey7 ig. Below) is $35\Omega$, the high-resistance voltmeter reads 9.7 V. When R is replaced by a $9.0-k\Omega$ resistor, the voltmeter reading drops to 8.1 V. What are the emf and internal resistance of the battery?
r $\approx$    $\Omega$(retain one decimal places)
$\varepsilon$ $\approx$   V(retain one decimal places)

  Suppose that you wish to apply a 0.25-V potential difference betweenqbyiqt4o.l 81 two points on the boq 1it8l4y.q human body. The resistance is about $2000\Omega$, and you only have a 9.0-V battery. How can you connect up one or more resistors to produce the desired voltage?    k$\Omega$

  A three-way lightbulb can produce 50 W, 100 r-:lm 6th wmt7W, or 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually or7mwm-t6h:r t l 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 9b r/2buw,nxzm from an electric outlet. Each of the wires connecting your apparatus to the 120-V source has a resistance per unit lengtxbw zubnr,9/2h of $0.0065\Omega/m$. If your apparatus draws 3.0 A, what will be the voltage drop across the connecting wires and what voltage will be applied to your apparatus?
$V_{wires}$    V
the voltage applied to the apparatus is $\approx$    V(Round to the nearest integer)

  Electricity can be a hazard in hospitals, particularly to patient,p; lqmnhk)8 is who are connected to electrodes, such as an ECG. For example, suppose that the motor of a motorizedni; hlqp,)mk 8 bed shorts out to the bed frame, and the bed frame’s connection to a ground has broken (or was not there in the first place). If a nurse touches the bed and the patient at the same time, she becomes a conductor and a complete circuit can be made through the patient to ground through the ECG apparatus. This is shown schematically in Fig. 19–60. Calculate the current through the patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy mustukb/m em9fv ou 3x08s+ a 45-V battery expend to charge a $0.40-\mu F$ and a $0.60-\mu F$ capacitor fully when they are placed
(a) in parallel,    $ \times10^{-3 }\;J$
(b) in series?    $ \times10^{-4 }\;J$
(c) How much charge flowed from the battery in each case?
$Q_a$    $\mu C$
$Q_b$ $\approx$    $\mu C$(Round to the nearest integer)

  A heart pacemaker is designed to operate at 72 beats/min aqe):dnwv384qt1+ch)w i of yusing 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 resistany u-iv:url :c9y(xx/rnp93x17mdyo *tw4uisce 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 “*qhhqdgnspx,2 dd;52tr 4l b ;bridge circuit” used to make measurements of resistance. The unknown resiq4hd;ntqr ;d, xd22hlbg 5 s*pstance to be measured, $R_x$, is placed in the circuit with accurately known resistances $R_1$ ,$R_2$, and $R_3$(Fig. Below). One of these, $R_3$, is a variable resistor which is adjusted so that when the switch is closed momentarily, the ammeter Ann Meter shows zero current flow.
(a) Determine $R_x$ in terms of $R_1$ ,$R_2$, and $R_3$.
(b) If a Wheatstone bridge is “balanced” when $R_1\,=\,630\Omega$,$R_2\,=\,972\Omega$, and $R_3\,=\,42.6\Omega$, what is the value of the unknown resistance?    $\Omega$

  An unknown length of platinum wire 0.920 mm in diameter is placed ase;b;w :g na+(p xk9sdp the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Belosbg kxa9:p+w;ed np(;w). 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 c*f) hbly 5 1j,:ypdpxcan be obtained by connecting fh*ly dbfp:)j p5yc1x, our identical capacitors, each having a capacitance C?

  The variable capacitance of an old radio tuner consists of four plates conn8cmmz7ag1 y p.ected together placed alternately between four other plates, also connected together (Fig. Below). Each mpgmz.a87y1c 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 40.8jeogz k5n 8 h (i3loeh.bf)-r l+b*1ad2ma uu/ V when 7.40 A is drawn from it and 47.3 V when 2.20 A is drawn. What are the emf and intei u2o +lbebnu5 rahg3l jkz8-.1h)f*m/(oae drnal 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 :)zxx/i:t exewff:(pqc3 *ol$4.0-k\Omega$ 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 capacitorcj eiww6)so-s (o+n)y 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), dk+*kcxn884ax+yz jqretermine
(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 outpf) d fnm; ra:4sybj4o) zem5.qut of 350 mA at 0.80 V when exposed to full sunlidao5 sbm4qr :;f fm z)ejn.y)4ght. A solar 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 o:qfcf yawipg+ at,); pza1e(:dyx c/:utput voltage of 12.0 V, but you need $V_T\,=\,3.0V$ for an experiment.
(a) Using the voltage divider shown in (Fig. Below), what should $R_2$ be if $R_1$ is $10.0\Omega$? $\approx$    $\Omega$(retain one decimal places)
(b) What will the terminal voltage $V_T$ be if you connect a load to the 3.0-V terminal, assuming the load has a resistance of $7.0\Omega$? $\approx$    V(retain one decimal places)

  The circuit shown in (Fig. Below a) uses a neon-filled tube asb5jz.wf .4ryz 4xm 9ni in (Fig. Below b). This neon lamp has a threshmrb.4xy4jfizz 9n. 5wold voltage $V_0$ for conduction, because no current flows until the neon gas in the tube is ionized by a sufficiently strong electric field. Once the threshold voltage is exceeded, the lamp has negligible resistance. The capacitor stores electrical energy, which can be released to flash the lamp. Assume that $C=0.150\mathrm{~}\mu\mathrm{F},R=2.35\times10\mathrm{~}^6\Omega,V_0=90.0\mathrm{~V}$ and Ann meter=105 V
(a) Assuming that the circuit is hooked up to the emf at time $t\,=\,0$, at what time will the light first flash?    s
(b) If the value of R is increased, will the time you found in part (a) increase or decrease?  ----待选择---- increase decrease 
(c) The flashing of the lamp is very brief. Why?
(d) Explain what happens after the lamp flashes for the first time.

a
b

  The current through the yjl:; lc vm,,;ow08f9 +yauc*oqqya r$20-\Omega$ 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 (Fisdml1 5(oj: twg. 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 q qyogtnye um,::)2q 7resistance 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 connrbq)e5v7g0qv2wg k(l ected as shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeter reading, the value oflrw5 7ev0)qgkq(2 bvg 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 xtm,;mise8o5(12 ifc( mx0blchu .ns2.5 W and 3.0 V is operated by a 9.0-V battery. To light the bulb at its rated voltage and power, a resistor R is connecte ;cfcxx(0s8lih2 m,estb ni5m(o 1m.ud in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$