Explain why birds can sit on power lines safely, whereas leaning a mn30- i ( v3w t b*btrsi8hca:yznx.aa9etal ladder up against a power line to 0.- 8rc y 9w*3n3bv taaa:(nizstxhbifetch a stuck kite is extremely dangerous.

Discuss the advantages and disadvantag,jo ,6 w 9(s9phwjuaeckc1zt,d 0zvj0 es of Christmas tree lights connected in parw,e1h906jdz9sp0vjjc,oa zu ( , kwc tallel versus those connected in series.

If all you have is a 120-V line, would it be possible qv-mu h5v1z 2zk 7z-wjto light several 6-V lamps without k27qv1-zuz-zh5vm jw burning them out? How?

Two lightbulbs of resistanceizk;+)dt *vuty + cjym+he),n $R_1$ 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. Aruv /s7 ),7g jrb o(teaf v+plvbm(6k4ve these connected in series or parallel? Ho frvs,jp6ulotm+7a)b 4/b gv( k(v7vew do you know?

With two identical lightbulbs an;k) pnppjc xw-4kd ,2nd two identical batteries, how would you arrange the bulbs and batteries in a circui)2kw-pc,jp n kxnd;4pt to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors)pe z sms -wf41,jx7m 0(ixqfw are connected in series to a battery, does the battery have to supply more power o z )xipmfswe-w4 1(jxf0q,m s7r less power than when only one of the resistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the o ,v:izzlva) ,7qmuj(mverall resistance of your room’s electric circuit change when you turn on an additio: v ml vq)(,ijazm,uz7nal 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below), doevh5cx1qk r+f pr7 *c5 ssc(c)ms the sign (or direction) of a battery’s emf depend on the direction of cu+ m)rfqc( 5hp 15src7c* sxkcvrrent through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “increasu5nx we;e4v85r 2yq09wafu5q gvv h;tes,” “decreases,” or “stays the same” to complete the following statements: 2erwq5v vw;u4n5u9v 580ayfgte ;hxq
(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 batterieswf vfcv2ualnwm lc9j-63m3nk ) *p :*b connected in series? For what use are they connected inw w:2m)a-ln3* kucnp lv3b * vjm9f6cf parallel? Does it matter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever exce5j,0 kxuld x r nx+--tsckpk:)ed its emf? Explain.

Explain in detail hot9lh o3 7:hdi76c8o4g+ z3fhko knaxdw you could measure the internal resistance of a battery.

Compare and discuss the formul6eupu9p6 s/lg6 dlfsqs 3fc7+as for resistors and for capacitors when connected in series and in parallel.lc69u3p l6e+ fgfu q/ss7ds6p

Suppose that three identical capacitors are connodq/q j1 0d17dvya q0xected to a battery. Will they store more energy if connected in series or/d71x 0 0ydqqod 1javq in parallel?

Why is it more dangerous to turn on an electric appliance when you are /:zc/2,f3wt yox .lri 6uos jqstanding outside in bare feet than when you are inside wearing shoes with thio,/cwu xz2fo:s.tr3 6 ijy/lqck soles?

(Fig. Below) is a diagram of a capacitor (o.75f cz70q ukmd( 3xszlsi 5tgr condenser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to move back and forth. Explain5q(l3zks5s70z tmu.f icdg7x how a current of the same frequency as the sound wave is produced.

Design a circuit in which twosw3xzkvu da,suv:,m:h m2.3 y different switches of the type shown in (Fig. Below) canmvdu.,s:kvyxa w,h3s23 uz:m be used to operate the same lightbulb from opposite sides of a room.

In an RC circuit, cur +k 8xw7i+,6dsx ncoksrent flows from the 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 not, where does the extc7k,ss kwnx ++o6di x8ra energy go?

What is the main difference between an analog volyo(;vl lnd7vjd-d cv.p. 1-bttmeter and an analog ammeter?

What would happen if you mistakenly used an s jxw8rv8+tk(d 94usu ammeter where you needed to use a vot9 sd+ (rxj8uw 4su8vkltmeter?

Explain why an ideal ammeter would have zero resistance andkle,dxh 79z9tqle h (8 an ideal voltmeter infinite resistanc qzet l, xlh7e99kd(h8e.

A voltmeter connected across aa/3 x0vstpp-g resistor always reads less than the actual voltage across the resistor whena0xvp -pg/ 3st the meter is not present. Explain.

A small battery-operated flashlight requires a single 1.5-V battery. The bulb xdc i8f,5to v0zbi:k2nx- vq0 is barely glowing, but when you take the battery out and check it with a voltmeter, it 2 -:zxbi 8v0,ktv0xof idq c5nregisters 1.5 V. How would you explain this?

  Calculate the terminal vol3 xh 2d5ywlcbv.1iq/j tage 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 cpp71kd ,mq* ru4jnj3p7khkyjyh7 -9resistance 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 aru: .ka8 pjpsfp0r z+4 $680-\Omega$, 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 a+.( m- ttt*milpd7zux $6.0-V$ 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 3.w4w qmlgcq-$12.0\,V$ shows a terminal voltage of $11.8\,V$ when operating in a circuit with two lightbulbs rated at $3.0\,W$ (at $12.0\,V$) which are connected in parallel. What is the battery’s internal resistance?    $\Omega$

  Eight identical lights are connected in series acro/0vktfn )z;wiy 3yo 4pss 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 pam +gj0l/qmp ,jrallel 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 cir7;-jefb:gxk ccuit reveals 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 quaz652d)b2vyeds 10xokex jk* hlitatively: deb ye5 jk6 zxkx2)*s 0dh21vo
(a) What happens to the voltage across each resistor when the switch S is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(b) What happens to the current through each when the switch is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(c) What happens to the power output of the battery when the switch is closed?  ----待选择----increasedecrease 
(d) Let $R_1=R_2=R_3=R_4=125\Omega$ and $V\,=\,22.0\,V$. Determine the current through each resistor before and after closing the switch. Are your qualitative predictions confirmed? Notice that the current through each of the parallel resistors is half of the total current, within the limits of significant figures. $I_1$    A $I_3$    A $I_4$    A Notice that the current through each of the parallel resistors is one third of the total current, within the limits of significant figures.$I_1$    A $I_2$    A $I_3$    A $I_4$    A  ----待选择----YesNo 

  What is the net resistance of the circuit connected to the b )qdju 9y+s:evattery in (Fig. Below)? Each resistance d+:us9e)yqjv has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are cwsk76tmw5us0+ 4 wq bdonnected to a battery as shown in (Fig. Below). Qualitatiuq+bw ws7 k0d4m65sw tvely, what happens to
(a) the voltage drop across each of these resistors, $V_{left}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0 
(b) the current flow through each, $I_{left}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0 
(c) the terminal voltage of the battery, when the switch S is opened, after having been closed for a long time? terminal voltage  ----待选择----decreaseincrease0 
(d) If the emf of the battery is 15.0 V, what is its terminal voltage when the switch is closed if the internal resistance is $0.50\Omega$ and $R\,=\,5.5\Omega$?
$V_{terminal\,closed}$    V
(e) What is the terminal voltage when the switch is open? $V_{terminal\,closed}$    V

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

  Calculate the current in the circuit of (Figu0 .nh4/yldas/u a7y p. Below) and show that the sum of all the voltage changes a/luu0 4psy.yhn7/ da around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each battery in (Fig. Below). 18V battezfy4a/ +0qnp: zxk1i4pr xk 4pry    V 12V battery    V

  (a) What is the potent6cm-vby f 34g.-ttjdv ial difference between points a and d in (Fig. Below a) (same circuit as Fig. Belotdj cg3-vv4y.t -b6 mfw 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.y2s( 7htfuxs : Below), find the potential difference between points a and b. Each resis2y(s h:ftusx7 tor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the currenttvb l m74vleaj:3m08ds 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 inteylp-z2q2j 1 q-zrr(y8bbwom 1rnal 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 a.+ yvzzux6 f(w 3*cgf+o0ybzcurrents in each resistor shown in (Fig. Below). The ofc *u+y(zzw0f+.vg3bx 6z yabatteries 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 batt8h cv56ln/ 0k-y)m r qc/zculhery 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 k- uf5da93f d4ca2yguFig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currents )kgf3ud/hmq)a 6,z w y$I_1$,$I_2$, and $I_3$ in (Fig. Below). Assume the internal resistance of each battery is $r\,=\,1.0\Omega$$I_1$ $\approx$    A(retain two decimal places)
$I_2$ $\approx$    A (retain two decimal places)
$I_3$ $\approx$    A (retain three decimal places)
(b) What is the terminal voltage of the 6.0-V battery? $V_{terminal}$    V

  What would the current :i q0s vat.r;hz;m6 tw$I_1$ 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 3.00ibrfg,a8nl2j8jw m2e 6 vg,8e V, are connected as shown in (Fig. Below). If each internal resis8j,bv8r6 eig 282laj gf,e nwmtance 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 cu7nwmwe,*)liip; f + napacitance 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 network of (Fig. Below), calculate thlgw,5: omok yf(q, 5dee voltage across each ,l,d 55k:mfo weg y(qocapacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of a circuit is to be reduced from 4800 pF ttuz5,d; 5qff to 2900 pF.d5fzut5 ,tfq;
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 acsf09qfvk y1 c*7qrj*yh )cdzqf7/*pm cidentally 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 circuq7y hiy(53zrhkn ad 5(it shown in (Fig. Below).

  In (Fig. Below), if lu(m-: u 7kpn*w omr.c$C_1=C_2=2C_3=22.6\mu F$, 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), supposiu7 l)rwvl25 ye $C_1=C_2=2C_3=16.0\mu F$, 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 xqj /5 wf/5 +ufaj+vff$V\,=\,78V$ 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 os)zr-g,m:43lr r g ne;sebud1f area A, are connected as shown in (Fig. Below). gse4zmen-ru3rd :lg; r1,sb)
(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 25v s1)c1 uf)opb0-pF capacitor hooked across a battery. It is desired to store three times as much energy in a combination of two capacitors by addiu 1)bc)pv so1fng 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 capacitance, ageb0pu6:ge a: s;1is vnd as a series combination they are connected to a battery with an emf of 25.0 V. If thg ; u ag1:vi60b:pesese 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often connectta5paspsadl to,m4 ()jjq 36 34a9gjued as shown in (Fig. Below). The leads are said to be capacitively coupled. A time constant of 3.0 s is typical and allows rapid chg 9 slsaaja)p6,44 tapo33j5(dmqtu j anges 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 resistance is: nps,hmw- ib5 $15.0k\Omega$, 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 Fixe* up 7yxb gvs64 syrrrq;;7,g. Below a (same as Fig. Below b) has $R\,=\,6.7k\Omega$ and $C\,=\,3.0\,\mu F$. The capacitor is at voltage $V_0$ at $t=0$. when the switch is closed. How long does it take the capacitor to discharge to 1.0% of its initial voltage?    $ \times10^{ -2}\;s$
a
b

  Two resistors and two uncharged capacitorrfa,c+tsdio1:ymp u3v 1c h5)s are arranged as shown in (Fig. Below). Then a potential difference of 24 V is applied across the combinationricvo,3 h:+c1fma15 psyt u d) 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 qw9pyjf 3qhm9pgzo. t uac5m9 j9p 4-6if the meter sensitivity is 4 gpzm9h9t3w.9j6qyc9 poqup5-maj f$30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sendvv ocf3,rlm6/8xn ls1s))jdsitivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resistanc x7kf2b64pjp ge 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 sencd m3f/ 4qqcqri.+gtfo2h6 0 psitivity 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 3tc 7(v8j5oyp7pa9uab9gwp e 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 resiv6;*wxsk*fk,reu+fvno 0 . c kstance 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 resistan;s,y m,bpi4u b l4a9lpce 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) xl;m30gexng should the voltmeter of Example 19–15 have to be in error by l0l3xe)x ; gmgness than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Bwjdj s3y 5-l:relow) 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 tojaf6 (qa; xwu1,sn;sv apply a 0.25-V potential difference between two points on ;vn1afu6 (qjas,w;xsthe 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 5)tp/ef m*6 du1iw1wsksv f*aav )7kq50 W, 100 W, or 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually or in parallel.*vm6w uk)/ 1eatsdfqis1 v7 *p)w fak5
(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 el) 3 g9xclcqi2hectric outlet. Each of the wires connecting your apparatus to the 120-V sourhclgxq )i2 93cce 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 i odoi80/mm zt9n 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 to a ground has broken (or was not there in the first pla80otmi9d/ moz ce). 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 as)z c1qb b71ff;l3tt g 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 bea9r yz-yi6eh;o ts/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’tbe;z.da/ l m;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” ut*l .s0uqjpv6cca x8+t: aw :osed to make measurements of reop6vwa cls c:qt +:8uaj*tx0.sistance. 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 platinw0wv6*0paax7t2mzblv4 wgn: um wire 0.920 mm in diameter is placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 havwlw*2 :n0w x6mag4atb0v 7zpve 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 connu5y f b-jz7 c(b azi.1dhyw42w0x;hieecting four i5-hb w4z0yj(i7ui2azy;hx d w .f1c ebdentical capacitors, each having a capacitance C?

  The variable capacitance of iwc 4gkzy ej )z:em301an old radio tuner consists of four plates connected together placed alternately between four other plates, also connected together (Fig. Be1:3ecy 0w4)jie mk zzglow). Each plate is separated from its neighbor by 1.5 mm of air. One set of plates can move so that the area of overlap of each plate varies from $2.0cm^2$ to $9.5cm^2$
(a) Are these seven capacitors connected in series or in parallel?  ----待选择----parallelseries 
(b) Determine the range of capacitance values. from    pF to    pF

  A battery produces 40.8 V when 7.40 A is drawn fr z 5zzpk */s/1n9 .,*yomwm 2hgn0oorpiemz 9oom it and 47.3 V when 2.20 A is drawn. What are the emf and internal 2s z e,mm./pm1rzn/n99oz5 o ykgoo iw0* zh*presistance 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 thpbixt0e6h 9l (e $4.0-k\Omega$ 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 capacitorx2.;p qz* st3j ;dcvpz 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. Bel /yd * ,s7-vu+wpn (1nkjutmqdow), determine
(a) the current through the 14-V battery $I_1$   $ \times10^{-5 }\;A$ ----待选择----downupward 
(b) the potential difference between points a and b, $V_a-V_b$.    V

  A solar cell, 3.0 cm square, has an output of 350 mA m4rrp/jsst8d g wha,/f69,utat 0.80 V when exposed to full sunlight. A solar pa ,6tmrj,aussp/g8r9dwh/ 4f tnel that delivers close to 1.0 A of current at an emf of 120 V to an external load is needed.
How many cells will you need to create the panel?    cells
How big a panel will you need, and how should you connect the cells to one another?    $m^2$
How can you optimize the output of your solar panel?    banks of    cells in series per bank, with the banks in  ----待选择----parallelseries  always have the panel ----待选择---- pointedturned  directly at the sun。

  A power supply has a fixed output voltage ofww.qgk 1,lo w 7:yuey5 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 ae(+xv4iqecqa 3 k3 0i,hwf4 kvs in (Fig. Below b). This neon lamp has a th+3vk,efiha4qiv w4 ( e 3c0kqxreshold 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 diq pqeil2ier) 1,;jgp7 y*1wthe $20-\Omega$ 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. Below) ka9tiro:;pq4 rl4irkr e)+; z, the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance of the circuit shown in (r+i6qe 0n0 dobkeet) b,8k 5wcFig. 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 connectemvja *wwv1uqid3l,+6isl qk n(5) l;sd 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 of R will no l kw1qlau6( )mqwl vvs5;,+dn*ii3jst 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 2.8 pm/arxwg xy8e3)ob- 5 W and 3.0 V is operated by a 9.0-V battery. To light the bulb at8pw/gx3b - roe8y)xma its rated voltage and power, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$