Explain why birds can sit on power lines safely, whereas leaning a me.1 kk el0.mhjital ladder up against a power line to fetch a stuck kite is extremely dangerousk.1.il jh 0emk.

Discuss the advantages 3az 8+ v*umx8b fj+i+oetsyq0 wkg)0sand disadvantages of Christmas tree lights connected in parallel versus those connected in sevxztsk+3a 8q+f*g0 j+m0)y wis e bu8ories.

If all you have is a 120-V line, would it be possible to light several 6)9+ ojgd4rjq0,q ac vk-V lamps withqd0q rj,jvao+4cg) k 9out burning them out? How?

Two lightbulbs of resistaimqd7ihhd+03z .tz h )nce $R_1$ 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 cbj. t st9+p)q+vydo 7aonnected in series or parallel? 9o.+ q)t7y +vspjbad tHow do you know?

With two identical lightbulbs and two identical bat3pqft )y7ifr:lc)9 wgd65b l nteries, how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligible internal resiyi )f lflw9dq)n bc7r65tp:g3stance.)

If two identical resistors are connected in series to a battery, does the battemrc*v0 /osy wlv+x -:ary have to supply more power or less: ovams*+rxl c /y-0vw power than when only one of the resistors is connected? Explain.

You have a single 60-W bulb o k*( t4a k/ktih6yjn6sn in your room. How does the overall resistance of your room’s electric circuit change when you4*y 6h/tskn a(6 jikkt turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (su+: ay;kr/ zc*mp dv-lich as in Fig. Below), does the sign (or direction) of a battery’s emf depend on the direction of curm-;kazy:*ldp cr/+ i vrent through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “7uh 2ty8b kws(lo 1 ++:y;y,rcyejbujwn 4;beincreases,” “decreases,” or “stays the same” to complete the following st r;+ :bjy7 wu2 yj1; ltb wobheue8(n4y,skcy+atements:
(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 conncy( rhd:l0( foected in parallel? Does it matter ylfc(:o0rd(h if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever exceed its emfu5up)m 5+v d7om;h tlx? Explain.

Explain in detail how you could measure the internalzw5uyao+;q 3lu 9 zte5 resistance of a battery.

Compare and discuss the formulas for resistors and for capac tf7qo0,us. 6vbo:pk mitors when connected qom 06bpvto:u ,7fsk .in series and in parallel.

Suppose that three identicalb;plug/p+yca8( x 7ltl: ucf2 capacitors are connected to a battery. Will they store 7bp uxl yl :l2;p(+/ taufg8ccmore energy if connected in series or in parallel?

Why is it more dangerous to turn on an elect. e nd8qx fi/mgk-au;bv-fm-2ric appliance when you are standing outside in bare feet than when you are insi-e.mm i ;ud8-n2/f-xkafqgvbde wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphone. Thefa3as v5j+u1gsr wn+b 7/fx7p changing air pressure in a sound wave cau/fxas 37g5ru+n7 v+ pwjfasb1ses one plate of the capacitor C to move back and forth. Explain how a current of the same frequency as the sound wave is produced.

Design a circuit in which two different switches of the type shown in (p7tuw 7i*ec ewu1 aoc):. b-ldFig. Below) can be used to operate thc-otb:.l7e)ia dw 7ueu1pw *ce same lightbulb from opposite sides of a room.

In an RC circuit, current flows from*d)jeb5* t/u dla qpfz/2le/p the battery until the capacitor is completely charged. Is the total energy supplied by the battery equal to thef 5u j*eep/ ddaltp/q)bl 2z*/ total energy stored by the capacitor? If not, where does the extra energy go?

What is the main difference y+wv7;ly eql5 between an analog voltmeter and an analog ammeter?

What would happen if you mistakenly used an ammeter where you needed to use a vn (q+ee:l9( *uefukq eolt(e+fue * (l k:uqqee9nmeter?

Explain why an ideal ammeter would have zero resistance and an ideal voltscb5cyvp7ur+u:+p 1ie o :qg*meter infir 57 p*gvs1b: q++icpeu yuoc:nite resistance.

A voltmeter connected across a resist 80uqh)yyq 9ypor always reads less than the actual voltage across the resistor when the meter is n)yyp90q8y uh qot present. Explain.

A small battery-operated flashlight requires a single 1.5-V battery. o6it y +nwgsuetqs.z) fktui6n)9/99The bulb is barely glowing, but when you take the battery out andgtzi6kqt9niu9 ye.)so69 / s )+ wftnu check it with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminarg b i,w9r+pfb/r1+y yl voltage for a battery with an internal resistance of $0.900\Omega$ and an emf of $8.50\,V$ when the battery is connected in series with
(a) an $81.0-\Omega$ resistor,    V
(b) an $810-\Omega$ resistor.    V

  Four $1.5-V$ cells are connected in series to a $12-\Omega$ lightbulb. If the resulting current is $0.45\,A$, what is the internal resistance of each cell, assuming they are identical and neglecting the wires?    $\Omega$

  What is the internal resistance of a x) gpnpd4 yh5p)e0 l/u$12.0-V$ 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 havpn q,:j)a ,a l4nz960xcb *t smxqrh7se a $680-\Omega$, a $940-\Omega$ and a $1.20-k\Omega$ resistor. What is
(a) the maximum,    $\Omega$
(b) the minimum resistance you can obtain by combining these?    $\Omega$

Suppose that you have;*hg 1+k mp5 mh)3ds,nsjezzh 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 ofe.et 9 /u/l7u vdt(vlf1aocq , $12.0\,V$ 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 conontoj;u6+/f ng24f se nected 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 parallels(+ nplglt4ov 1 .t4i oy:k( 9i2hogyp 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 reveal/awbv2mazyag: e29u 8s 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). Ancxv3* zpbn0w xad/x9l w-*w3f swer qualitatively: vx0 lpx-* zdf c3waxb*wwn3/ 9
(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 cosxub/e .g 3u1rnnected to the battery in (Fig. Below)? Each resistanx.3 rgu/s1bu ece has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown b +(/qopf7so;ei e/huin (Fig. Below). Qualitatively, weu pe os;+o/i 7h/b(qfhat happens to
(a) the voltage drop across each of these resistors, $V_{left}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0 
(b) the current flow through each, $I_{left}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0 
(c) the terminal voltage of the battery, when the switch S is opened, after having been closed for a long time? terminal voltage  ----待选择----decreaseincrease0 
(d) If the emf of the battery is 15.0 V, what is its terminal voltage when the switch is closed if the internal resistance is $0.50\Omega$ and $R\,=\,5.5\Omega$?
$V_{terminal\,closed}$ =    V
(e) What is the terminal voltage when the switch is open? $V_{terminal\,closed}$ =    V

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

  Calculate the current in the circuit of (Fig. Below) h3 qbij(qn( q:and show that the sum of all the voltage changes around the cir(ib hn (q3:qjqcuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminakk u4xr 1mag5xesxno1m/3j2 6 : auh6il voltage of each battery in (Fig. Below). 18V battery =    V 12V battery =    V

  (a) What is the potential difference between points a and d in (Fig. Below k;ha z3- w)zo) 1bssd:)twstxa) (same circuit as Fig. Below b, oxt )z)bswskh; wt3:1s-a z)d), $V_{ad}$    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 between podpec b hn+(h .3b.3nhcints a and b. Each r3hcn.ce.ph (dnbb 3+ hesistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the currents through o ikauqh +1tka;l;,+96cs lth $R_1$ 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 nv5 *3::hf hs/+ ubvvv7serrzlb,d( fresistance $r\,=\,1.2\Omega$.
$I_1$ $\approx$    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 resijjjl *ld3y+2 5 cib2mbstor shown in (Fig. Below). The b2+ ll2j*cmi3jy j d5bbatteries 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 k pd7ip8 u39ml $r\,=\,1.0\Omega$.
$I_1$ $\approx$    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 ut/v3z ndcwr4 c218ozin each resistor of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the cus-ah:q8 dmg5rrrents $I_1$,$I_2$, 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 currenivy*r/0+ jy2ze /mqh vt $I_1$ 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 3gs+am2-y 4lc0i xij)x.00 V, are connected as shown in (Fig. Below). If each internal resistance ixml42jgx)s i0 -y ci+as $r\,=\,0.100\Omega$ 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,c2dtjloo8 6e:w ko/i7 zj;ci5 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 whole networ / xl(*,bbzyu .-nlk;:fseqhek of (Fig. Below), calculate the voltage across each capacitor. yfz*xubl(qs;. kn /hl, -:be e
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portis eh 6nf,gf/bktyked *2+1mjlo s 6.-q k-6atoon of a circuit is to be reduced from 4800 pF to 2900 pF.j-o+a set6dy fg-b/msf,2hte qk6 16.n*lkok
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 c:x8f.m d8oo t,wt +efronstructed using a $5.0-\mu F$ capacitor instead of the required $16-\mu F$ value. Without removing the $5.0-\mu F$ capacitor, what can a technician add to correct this circuit?
   $\mu F$
conneected in  ----待选择----parallelseries 

Determine the equivalent capacitance of the circuit shown in - d07z 2ajv6hc7r cedx(tlv *x(Fig. Below).

  In (Fig. Below), if 2y+w. 1uz2dzy :qu-+n 8ifnnxy)mi ed$C_1=C_2=2C_3=22.6\mu F$, 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 t;s9/ rf9jyrce $C_1=C_2=2C_3=16.0\mu F$, 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 +kf:2n* z v20wdsmd( lqc ye.x$V\,=\,78V$ 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 plat; 4+lgkpy j8ooes, each of area A, are connected as shown in (Fig. Below). 84pl;ko o jg+y
(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 capa(s hsb4ut bccb84*mx :taaud* 5.fe 3ecitor hooked across a battery. It is desired to store three times as much energy in a combination of tw83e c5:stmub aab*4s(bxtehc ud4f. *o 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 connecteiamws8d( sgm-m7 p7ybs(45gdd in series with an unknown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 1858 5wimymdmsd7sbas ( 7g(- pg4-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 lq,1e-( x6 tgllb iewq6eads are said to be capacitively coupled. A time constant of 3.0 s is typical and allows rapid changes in potential to be reteq-,xl e 6gi6(w 1qlbcorded 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 resistance iiyrkzl/6 x7 + h,h8psm-do)lzs $15.0k\Omega$, 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 m 96q oyhdh8sc*0r ;lexcy 5.g(same as Fig. Below b) has $R\,=\,6.7k\Omega$ and $C\,=\,3.0\,\mu F$. The capacitor is at voltage $V_0$ at $t=0$. when the switch is closed. How long does it take the capacitor to discharge to 1.0% of its initial voltage?    $ \times10^{ -2}\;s$
a
b

  Two resistors and two uncharged capacitors are arjl n(kjh,(c, oranged as shown in (Fig. Below). Then a potential difference of 24 V is applied across, ( ,kjhc(njol the combination as shown.
(a) What is the potential at point a with switch S open? (Let $V=0$ at the negative terminal of the source.)    V
(b) What is the potential at point b with the switch open?    V
(c) When the switch is closed, what is the final potential of point b?    V
(d) How much charge flows through the switch S after it is closed?    $\mu F$

  What is the resistance of a voltmeter on the 250mt,t ahd3s -(u-V scale if the meter sensitivity itt-h m(sa3d, us $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensiti)mn4 jp9wj ez urh,,o,vity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an inter)r1t ,wd+ti bhnal 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 sr (tpbmc/rmxo l3 uxx,/da2(*ensitivity 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 od dg.7/ g:b kgrpng:k2f 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 neglif4 /yx;ixp3,8mpo yy6(pu ewqgible internal resistance is connected to a $R_1$=$38-k\Omega$ and a $R_2$=$27-k\Omega$ resistor in series. What reading will a voltmeter, of internal resistance $95k\Omega$ give when used to measure the voltage across each resistor? What is the percent inaccuracy due to meter resistance for each case?
$V_1$$\approx$    V (retain one decimal places) % error    % too  ----待选择----uplow 
$V_2$$\approx$    V (Round to the nearest integer) % error    % too  ----待选择----uplow 

  An ammeter whose internal rz kjgd5syc*1 adxeee7o/ 66/ gesistance 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 of Example 19–15 havx2o-qqe7+ ppp 2iwr)h e to be in error by less iwq7p2 )x+2e rq-ophp than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) igl8 hn.m fr1c4ty3a w7cq 2+bs:hy5uks $35\Omega$, 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+,(z hw6xsnnqr7 b3 ty a 0.25-V potential difference between two points on the human body. The re63w z hn ny+srbxq(,t7sistance 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 W, or 150 W, at 120 cgs*4rb; 6hj uV. Such a bulb contains two filaments that6h sg 4ub*cr;j 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 o+5udl w9h2 /ue/c rwlzutlet. Each of the wires connecting your apparatus to the 120-wlcl9ze+d ur w/5uh/2V 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 hazardy0uc -:j:.uovwi9ibb in hospitals, particularly to patients who are connected to electrodes, such as an ECG. For example, suppose that the motor of a motorized bed shorts out to the bed frame, and the bed frame’s connection .ji9 ob:wic vy0- b:uuto 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 battery k2t:zt;last;blt8t9expend 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 desy1itr ma ,6lbfif+50 figned to operate at 72 beats/min using a $7.5-\mu F$ capacitor in a simple RC circuit. What value of resistance should be used if the pacemaker is to fire (capacitor discharge) when the voltage reaches 63% of maximum?    $ \times10^{-5 }\;\Omega$

  Suppose that a person’s body resijm. ( kg4. ok6u(yeyrsw m75nqstance 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 id26am5xt 4yg4 ( wpqmto make measurements of resistance. The unknown resistance to be me pda 2m(q5ywg4mxi6t 4asured, $R_x$, 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 mmy4hns ,01jewu8j v0c d in diameter is placed as the unknown resistance in a Wheatstone bridge,0v0sejj1dcwynuh 48 (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 colj n ot-e4/3ulnnecting four identical capacitors, each llutj4 en3/ o-having a capacitance C?

  The variable capacitance of an old radio tuner consists of four plates cof*7,t+ f lutxh*enm4p3eprx, nnected together placed alternately between four other plates, also connected together (Fig. Below). Each plate is separated from its neighbor by3fhxefmp,lnrt,pu + *x7 t*e4 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 it and 47.3 V when 2aycx pic ;r, 5.e-faj:.20 A is drawn. What are the emf and internal resistance of the battery-5 ,.cfi ryexpj:;aa c?
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 themnduv2 o:uzqj h5;23(p4fml b $4.0-k\Omega$ 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-platehsek8zfl v5dev58:5umh ); u y 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), determdnn6p-cib+d1r m4l(*yd ;:;jh zktw dine
(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, hgap,35yx(sdx, m / nffas an output of 350 mA at 0.80 V when exposed to full sunlight. A solar panel that delivers close to 1.0 A of current at an emf of 120 V mfxf/, g pxdys, 5na(3to 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 ouw+)7w xnv4-do lde-ectput 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 j/s9n sfxpc ms/9do: 8my gn4)a neon-filled tube as in (Fig. Below b). This neon lamp has a threshold voltd/x /)jmsgsy8 onpsnm4:c 9 f9age $V_0$ 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 u k:+ao wk5ly4 r:v2iavf r;,d4i7tutthe $20-\Omega$ 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. Bftk 2:5ny,nqvv3km g n6t6a:q elow), the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent b6lx6t .c:icuresistance 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 connected ankz-tev( e c rdb. i87rhng(1(syc9c+s shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeter readgs ez((1evr 7k9+-(bnyc.8hi ncdrtc ing, 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 3.08,3a i;fjffhy bb)lz1 V is operated by a 9.0-V battery. To light the bulb at its rated voltage andy ,bf3l1a ;ihbj f)f8z power, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$