Explain why birds can sit on power lines safely, whers 8 osr7)5wdnnxsxz- :eas leaning a metal ladder up against a power line to fetch a stuck kite is extremelyrw sxnx5-z8 7d:no)ss dangerous.

Discuss the advantages and disadvantages of Christmas tree lights connecog9b (0elygvr-;t fd7ted in paralleregdoy9g-; 07f(tl v bl versus those connected in series.

If all you have is a t;xjiiacmojup 7ie6s 7r8q-1 v:l90*l g.g if120-V line, would it be possible to light several 6-V lamps without burning them out? Ho81*7xoiugcjg- vfleqp. ; iril jsitm 96: 70aw?

Two lightbulbs of resist vt.q *c/wjjt ,ec5y 98pzadyig :s9s:ance $R_1$ 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 gv )gvu, 29xeto:ugg; often double outlets. Are these connected in series or parallel? Hog t:2eog, v9v g;gx)uuw do you know?

With two identical lightbulbs and two i )rl8q1qmu jdfkv:hijx.;8a4 e *ep9cdentical batteries, how would you arrange the bulbs and batteries in a c9i.e) dc8 lmfq1*u;hk4v8a e: jrpjqx ircuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in serim-: u6ylu:qsv* g0+ap 8bvta qes to a battery, does the battery have to supply more power or less power tha8qv:s+qgyt:m6 b0a-ul *vup an when only one of the resistors is connected? Explain.

You have a single 60-W bulb on in your roo,nj -2riocz0 em. How does the overall resistance of your room’s electric circuit change when y e2io0 njrzc-,ou turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule(,nq6ef dnzogo w o.hbj-/4)rkdk 6 g: (such as in Fig. Below), does the sign (or direction) of a battery’s emf depend on the directigd zbk:e-orf6d ,6 /qnn.kj)w(o4gho on of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “increases,”wsac e:rj9dd-pqt )2; “decreases,” or “stays the same” to complete the following statementjt r:c ddq9w p-;)aes2s:
(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 1rxd llro 3h0:) ;zrql bkee0:in series? For what use are they connected in parallel? Does it me)r0q r1b0el ozk3hxl:d ;rl:atter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever evt xpb-45du ce t:; 4nrl*;nnpxceed its emf? Explain.

Explain in detail how youfj f)zlfytv -1r ur*5-c ,p fh(ybes*6 could measure the internal resistance of a battery.

Compare and discuss the formulas for resistors and for capacitors when connuzc h,lbd1c.sy7 p q/)ected in series abuc.7ql1,)/ psc dhzynd in parallel.

Suppose that three identical capaci hz5eb6l9 yl8; v)c+ztbeaa7stors are connected to a battery. Will they store m5e)a 9zb+v acb z 8hlls6ye;t7ore energy if connected in series or in parallel?

Why is it more dangerous touoe)ptboro3ria c h24 s8/ v37 sa+n-h turn on an electric appliance when you are standing outside in bare feet than when you are insir83 /vs)onaoore-4iu tphbc 2 a+73h sde wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or con *5 nd4c/s m9tvfyoa.idenser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to move back and forth. Explain how a current of tms ny.dfio 54v9 t/c*ahe same frequency as the sound wave is produced.

Design a circuit in which two dicmcf:5 )5i vruf)jrd 4fferent switches of the type shown in (Fig. Below) can be used to operate the same lightbulb u)d)r4m 5c rvji5f:cffrom opposite sides of a room.

In an RC circuit, current flows from the battery until the capacitor is completeaao8:ndbfx9 4ly charged. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If no9n 8b4fax: oadt, where does the extra energy go?

What is the main difference between an analog voltmeter and an analo e 0h4zz.39ouam )wbimg ammeter?

What would happen if you mistakenly used an ammeter 1dl:sk7i ha 6zwhere you needed to use a voltmete6k a:l71h isdzr?

Explain why an ideal ammeter would havey4v ud.hm. 7p9focgw9 zero resistance and an ideal voltmeter infinite resistang wcy.p.9d f7vhomu94 ce.

A voltmeter connected gf pe0 tmc;5b /st(d3/ rhoa*aacross a resistor always reads less than the actual voltage across thet 3as bdcm;/rhftg p( /o*0a5e resistor when the meter is not present. Explain.

A small battery-operated flashlight requires a single 1.5-V battery. The bke r)fh6c.4lh dkf:c/ulb is barely glowing, but when you take the battery out and check it with a voltmeter, it registers 1.5 V. How would 4c) :hdrfc6lf/e kk .hyou explain this?

  Calculate the terminal voltage ,byz; n,caba fai967y)9fw njfor 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 resistanc-z r+88a;xqviji3i 6l7 yrbj ze 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 y cua3m,8 -ygss(0t2)loyaks $680-\Omega$, 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 sr0lzhq59qgk5r ;rvay/x(q- p w a(a5a $6.0-V$ 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 at +b6,xl8jz x$12.0\,V$ 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 lightsv+ mxr;gmtcc( :hy01li:c4e g jbd)1v are connected in series across a $110-V$ line.
(a) What is the voltage across each bulb? V$\approx$    V(Round to the nearest integer)
(b) If the current is $0.50\,A$, what is the resistance of each bulb, and what is the power dissipated in each?
R $\approx$    $\Omega$(Round to the nearest integer)
P $\approx$    W(retain one decimal places)

  Eight lights are connected in para 3dyb(h7ng u /d.mn9jxji :9cg krj6/gllel 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 $ =    $\Omega$
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 rim,: dylpz ,+ceveals that a $480-\Omega$ resistor was inadvertently soldered in the place where a $320-\Omega$ resistor is needed. How can this be fixed without removing anything from the existing circuit?    $\Omega$

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

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

  Consider the network of resistors shown in (Fig. Below). Answer qu+rpnt;07 xnzb alitatively: rxz7tb;0+npn
(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 /loepp:nrzr2l(w( ze1/*v t )v bz/hg of the circuit connected to the battery in (Fig. Below)? Each resistance hb *t/v 1gl:z2pp( vze(zr)w//ehnorlas $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown in (Fig. Belowhtq2it+ruh; ( )pfo (f). Qualitativ qpfho+;(t( u2 hirft)ely, 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 o)agebu wf2 18:p;un vwf (Fig. Below) and show that the sum of all the voltage changes around the circuit is zerou: 8w)ugavwe2fb1 p;n.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminaw 3yy jwdbbazsp7a3; q9ga :+3l voltage of each battery in (Fig. Below). 18V battery =    V 12V battery =    V

  (a) What is the potential difference between points a 76wrjxxyv:x 0 and d in (Fig. Below a) (same circuit as Fig. ry7x:x x0w jv6Below 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 difference bq 6pq:rgn ,ij 38wmzcxeh7b4 ;etween points a and b. Each resistozce;4nb ,m8piq w:h rx7qg36jr has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and di qu)sx f:ln7)f0yw q6lrections 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 :b m te(97pq6lpy.kvw 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 shownw5 (a2s fkrcr*b2o1x jq-t 0jeaf37o a in (Fig. Below). The batteries have emfsa jfq5 1rro*f27ak xst 20jobe-w(a3c 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, asst70mon r4h5x duming 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 eac1)8j:v2mah-s rzickn h resistor of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currents u) c8boc) +1ys-z 9e*sotkfhr$I_1$,$I_2$, 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 curre*/hgd j0e 2ihsc7 mfv,dgp;3s nt $I_1$ 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, , v j(n0wn/aerare connected as shown in (Fig. Below). If each internal resnv( ,j/n rwae0istance 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 dw8+ pe ol0232qyjupepF, 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 wholeisqzl. .hd z/. network of (Fig. Below), calculate the voltage ac qs..zi z.dl/hross each capacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of a circuit e q )g2,mqs:yxis to be reduced from 4800 pF to 2900 pF. mgqq: ) ,2ysex
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 con4nzazb11n iqj ) 8/fdahsu o*j89fs.vstructed using a $5.0-\mu F$ capacitor instead of the required $16-\mu F$ value. Without removing the $5.0-\mu F$ capacitor, what can a technician add to correct this circuit?
   $\mu F$
conneected in  ----待选择----parallelseries 

Determine the equivalent capacitance of the circuit shown i*-o:6uq) t, ryvhbhsjn (Fig. Below).

  In (Fig. Below), if r 38xkmkc2bj0oof2 d1 $C_1=C_2=2C_3=22.6\mu F$, 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), suppose / (jm9tnrvg+y $C_1=C_2=2C_3=16.0\mu F$, 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), letp hu.e rq:907cnqqq.v $V\,=\,78V$ 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, eac*h ki( y.rznn l7aomr*:n;,xw h of area A, are connected as shown in (Fig. Below).i*r7lz.n(ar y :kxn,nwm *ho ;
(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 v 7swi0 4 cg xxlqd(5gdt(6iy,-/lgfi250-pF capacitor hooked across a battery. It is desired to store three times as much energy in a combination of two capacitors by adding a sil6-di5,7x gw0 l(gif /qs( y4cdtvigxngle capacitor to this one.
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is connected in series with an unknown capacitance, and gcd 5ma1f l *,ky6td /rf(tq-pm;ra7uas a series combination they are connected to a battery with an emf of 25.dt/ctr6 ga q7fu,;l1pmd arfmky( 5* -0 V. If the 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often connected n5a:5hsovig; q) )hp has shown in (Fig. Below). The leads are said to i5)hh5ha :n svog;pq) be capacitively 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 Fig. Below b), the total reqiw ,bp p6d4ha5*/jo zsistance 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. Belo5w lwu/ zo0w*jw 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 unc m 6wl94 q4fwgffdb:,charged capacitors are arranged as shown in (Fig. Below). Then a potential difference of 24 V is applied across the comdb6 qfl4:gf c9ww mf,4bination 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 jpygrrsrt-;yz 7/pb:10h pj9 0. ,fmk*ovjyi the meter sensitivity is t 1p*yjshj -r.: f0,b7kz/0jivp p roym ry9g;$30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensith popkz 9ekt :hipde;7ggr r 47.g*0r,ivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an int;vp s4 w135dgwc9 fykiernal resistance 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 sensitivityo jq92s7lk/nd 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. It consists gc 7mdodw 9+7g9)waz/teg5ar 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 rekq j(zq kf:5ivnu1 d-1vx*ec .sistance is connected to a $R_1$=$38-k\Omega$ and a $R_2$=$27-k\Omega$ resistor in series. What reading will a voltmeter, of internal resistance $95k\Omega$ give when used to measure the voltage across each resistor? What is the percent inaccuracy due to meter resistance for each case?
$V_1$$\approx$    V (retain one decimal places) % error    % too  ----待选择----uplow 
$V_2$$\approx$    V (Round to the nearest integer) % error    % too  ----待选择----uplow 

  An ammeter whose internal resistanub*61g0t ws zyce is $63\Omega$ reads 5.25 mA when connected in a circuit containing a battery and two resistors in series whose values are $750\Omega$ and $480\Omega$. What is the actual current when the ammeter is absent?    $ \times10^{ -3}\;A$

  A battery with $E\,=\,12.0V$ and internal resistance $r\,=\,1.0\Omega$ is connected to two $9.0-k\Omega$ resistors in series. An ammeter of internal resistance $0.50\Omega$ measures the current, and at the same time a voltmeter with internal resistance $15k\Omega$ measures the voltage across one of the $9.0-k\Omega$ resistors in the circuit. What do the ammeter and voltmeter read?
$I_{source}$   $ \times10^{ -4}\;A$
$V_{meter}$    V

  Two $9.4-k\Omega$ resistors are placed in series and connected to a battery. A voltmeter of sensitivity $1000\Omega/V$ is on the 3.0-V scale and reads 2.0 V when placed across either resistor. What is the emf of the battery? (Ignore its internal resistance.) $\approx$    V（Round to the nearest integer）

  What internal resistance should the voltmeter of5m 5d vyf eh)lfrc1. .(kyijk6 Example 19–15 have to be in error by less than 3%? 6 ef5kj5lfyihy d1v.c.()rkm$\approx$    k$\Omega$

  When the resistor R in (Fig.v t -ylvqi01r3 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 0.25-9fl1 dp o.vl3sV potential difference between two points on the human body. The resistance is llo3vf19s .d pabout $2000\Omega$, 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 canrf /lrh49-of jb7h8zj produce 50 W, 100 W, or 150 W, at 120 V. Such a bulb contains two filamentjb/4r7jrl9 zo8 f-fhh 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 appar jt.h7feg1uuln k74q x.5q9tksos34i k7q3pdatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to theilxuknkq s.jt4 qusgp k1 h f5 t7q7de33o74.9 120-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 hospital)mxup b0-e 6g9q4azh bs, particularly to patients who are connected to electrodes, such as an ECG. For example, suppose that the mqzpm9h046)- beaxugb otor of a motorized bed shorts out to the bed frame, and the bed frame’s connection to a ground has broken (or was not there in the first place). If a nurse touches the bed and the patient at the same time, she becomes a conductor and a complete circuit can be made through the patient to ground through the ECG apparatus. This is shown schematically in Fig. 19–60. Calculate the current through the patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must a 45-V battex*6 yqge.f i2ujo1p*rtht4 j 9ry 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 de jckuqp8av1 (j6b7:c -isl8gb lo:j h0signed to operate at 72 beats/min using a $7.5-\mu F$ capacitor in a simple RC circuit. What value of resistance should be used if the pacemaker is to fire (capacitor discharge) when the voltage reaches 63% of maximum?    $ \times10^{-5 }\;\Omega$

  Suppose that a persoua2vnc cc67u 1n’s body 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 circuit” ugfc.: r.ni j),nn4d besed to make measurements of resi.c,nd:jb.engi f )r4n stance. The unknown resistance to be measured, $R_x$, is placed in the circuit with accurately known resistances $R_1$ ,$R_2$, and $R_3$(Fig. Below). One of these, $R_3$, is a variable resistor which is adjusted so that when the switch is closed momentarily, the ammeter Ann Meter shows zero current flow.
(a) Determine $R_x$ in terms of $R_1$ ,$R_2$, and $R_3$.
(b) If a Wheatstone bridge is “balanced” when $R_1\,=\,630\Omega$,$R_2\,=\,972\Omega$, and $R_3\,=\,42.6\Omega$, what is the value of the unknown resistance?    $\Omega$

  An unknown length of platinum wire 0.920 mm in diameter is pla+ sv5jc7rtsjvqk12+*1z ehr s ced as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 have resistance of*vvcksj 1js+5 zrsq+17rteh 2 $38.0\Omega$ 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 connec ea f9lgf6zkmz .*nvi2il2vj *7h ):wpting four identical capacitors, each having a capacitance:l)h* n9l.e6i z* az 7f2jvfw2k gimpv C?

  The variable capacitance of an old radio tuner consists of f2/l2cmn/na;(v /tx9 yy txk*t:bvjf four plates connected together placed alternately between four other plates, also connected together (Fig. Below). Eav;vf ttx/x2nj 9k( nlb* tmfyy/c/a2 :ch 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 w-(8jti4) h k wv/: . vhfpd-d(mnvckz+ lfte*yhen 7.40 A is drawn from it and 47.3 V when 2.20 A is drawn. What are the emf and internal resiev n.f)(tc yj4m8vlhdi-*w(+ :dhktvz /k- pfstance 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 ohzqk .9scj0)+ d e,ei j--hdx:qh*kathe $4.0-k\Omega$ 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 p1gysrm /t7/g l1e.51so ,h5fsoo crocapacitor 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), determine huxmi(b n;t ) iui;i*0
(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 3.nn+j xxf .2rvat3r);t al -op50 mA at 0.80 V when exposed to full sunlight. A solar panel that delivers close to 1.0 Atnl).axv rj+ft;a - 2prnx .o3 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 out bg46xbamj +i wr5uq)+put 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 to d.ye80ug72l)flu+ m;k glpsube as in (Fig. Below b). This neon lamp has a uepo0;lus m8 fky gl7)l+.d2gthreshold 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 thyae)+3jwua , oh(qg.du j+j 1ge $20-\Omega$ 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. Bjipefwbzv ;(thryub15 *. *z8elow), 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 show wgh (b.sptl47 )/fixfn 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 con nbxb2 t)xso xkx3g;60nected as shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the an6 23xtk)o0bxsxgb; xmmeter reading, the value of R will not quite be $V/I$ (as in Ohm’s law) because some of the current actually goes through the voltmeter. Show that the actual value of R is given by
$\frac{1}{R}=\frac{I}{V}-\frac{1}{R_\mathrm{V}}$,
where $R_V$ is the voltmeter resistance. Note that $R\approx V/I\quad\mathrm{if}\quad R_\mathrm{V}\gg R$ .
(b) A voltmeter and an ammeter can also be connected as shown in (Fig. Below b) to measure a resistance R. Show in this case that
$R=\frac{V}{I}-R_\mathrm{A},$
where V and I are the voltmeter and ammeter readings and $R_A$ is the resistance of the ammeter. Note that $R_\mathrm{A}\quad\mathrm{if}\quad R\approx V/I\quad\mathrm{if}\quad
R_\mathrm{A}\ll R.$

  A flash lightbulb rated at 2.5 W and 3.0 V is operated by a 9.0-V batfne.s;1l , t m0,k :l,/h a)ezqkns4dq rre0hhtery. To light the bulb at its rated voltage and power, a resistor R is connected in series as f eqe:r;) k,l,n1 .zh /drhsnk4l0tmhq0,aseshown in (Fig. Below). What value should the resistor have?    $\Omega$