Explain why birds can sit on power lines safely, whereas leaning ah b3u3 dpg:q;f metal ladder up against a power line to fetch a stuck gfh:p3;uq 3db kite is extremely dangerous.

Discuss the advantages and dl f9po 203cy8 mkbw*ziisadvantages of Christmas tree lights connected in paralli9zbolpk*8cy m f2w30 el versus those connected in series.

If all you have is a 120-V line, would it be possible to light several fu*qvgk 7g nb6vc ,nm ,8pvjx,80w)mw6-V lamps withv,68w*gu,wfnn, vjq 8gc pv7bk 0xm)mout burning them out? How?

Two lightbulbs of resistancp5 8)m w-wjw)r /;cykq)qpg: y2fqtgse $R_1$ and $R_2(R_2>R_1)$ are connected in series. Which is brighter? What if they are connected in parallel? Explain.

Household outlets are often double outlets. Are these connected+3k i .6r3 p;mmggpo*ktp-n lb+2 pxms in series or paragp *+r-bi3kl pm6xsmo2pm.pgkt n3;+llel? How do you know?

With two identical lightbulbs and two identical battn6am.n1e0qh *gmx ls2d,b6 hweries, how would you arrange the bulbs and batteries in a cirewaqx1 6 d.h2m nnml *0g,sh6bcuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in sy n zvar (kjq1ewt*yx*/1.pn/eries to a battery, does the battery have to supply more power or less power than when only one of the resistors is connected? Exa/ nzxy*rv1w1k qptn(ej.* y/plain.

You have a single 60-W bulb on in your room. How does the oviact f+- +y2z7xun28b vmlk6eerall resistance of your room’s electric circuit change when you tu m6y t+zfcv22e8abxu-likn7 +rn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Be6que790 wlt hkp mp(*qlow), does the sign (or direction) of a battery’s emf depend on the direction of current through p qept7 *l wm9q6(h0ukthe battery? What about the terminal voltage?

  Given the circuit shown inc ooodnz 7.h2ht5) 2se Fig. 19–36, use the words “increases,” “decreases,” or “stays thezon).oh d esh o7t522c same” to complete the following statements:
(a) If $R_7$ increases, the potential difference between A and E  ----待选择----stays in samedecreaseincrease . Assume no resistance in Ann meter and power supply.
(b) If $R_7$ increases, the potential difference between A and E  ----待选择----stays in samedecreaseincrease . Assume Ann meter and power supply have resistance.
(c) If $R_7$ increases, the voltage drop across $R_4$  ----待选择----stays in samedecreaseincrease .
(d) If $R_2$ decreases, the current through $R_1$  ----待选择----stays in samedecreaseincrease .
(e) If $R_2$ decreases, the current through $R_6$  ----待选择----stays in samedecreaseincrease .
(f) If $R_2$ decreases, the current through $R_3$  ----待选择----stays in samedecreaseincrease .
(g) If $R_5$ increases, the voltage drop across $R_2$  ----待选择----stays in samedecreaseincrease .
(h) If $R_5$ increases, the voltage drop across $R_4$  ----待选择----stays in samedecreaseincrease .
(i) If $R_2$,$R_5$, and $R_7$ increase, power supply (r = 0)  ----待选择----stays in samedecreaseincrease .

For what use are batteries connected in series? For what use are they c-n s:zc7dtoc 8d 2zsx3onnected in parallel? Does it matter if the batteries are nearly idents3zn2 :t- xdzo8cs 7dcical or not in either case?

Can the terminal voltage of a battery es6(.lo(q ) rnjty2cuu ver exceed its emf? Explain.

Explain in detail how you could measure the internal resistance of a w (*rt:/gqu ayz5yt;xbattery.

Compare and discuss the formulas bgb x4yzt ;y,udw u79hk;j)d:for resistors and for capacitors when connected in sertdwky)gdj7b9 b:; 4,;uhuzx yies and in parallel.

Suppose that three identical capacitors are connected to bed m/ seb-( 40nrx2 -bf1jovn (zbst5a battery. Will they store more energy if connected in jb-1r2nxn(sbst /(bf -oz0 meb 4 ved5series or in parallel?

Why is it more dangerous to turn otnow8 jaym1i(;lj 0a u kjjy9u(.yw.u,0fh w7n an electric appliance when you are standing outside in b w.jw0aj0tw hu 7;ymilk (n(.9u8yyu oa, jjf1are feet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagrvnrz9ygh:)r69g fr( /d s v dpis;*m05hf yfv/am of a capacitor (or condenser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to move back and forhv (md/r;in)6p /vr5sf y*9v0zdfg:sr 9hfyg th. Explain how a current of the same frequency as the sound wave is produced.

Design a circuit in which two difn8 0duj a6kq2xferent switches of the type shown in (Fig. Below) can be used to operate the same lightbd2ua j kqxn860ulb from opposite sides of a room.

In an RC circuit, current flows from the battery until the capacitor is compy+g4bxvai,h4*jax.3 p .bxqm letely charged. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If not,x *qa ,.h ivba43 ym.4xj+gxbp where does the extra energy go?

What is the main difference between an analog voltmeter anvi1dvqy .4 ui*d an analog ammeter?

What would happen if you mistakenly used an ammeter whe80cih: nh0vrzl* krc2re you needed to use a voltmrl80 ivc h: z*kr20cnheter?

Explain why an ideal ammeter would have zero resistance and an ide(py t)jt/9qaon46z njal voltmeter infinite resistance.tz 96/qyjp()4anjon t

A voltmeter connectedf*l aem)znng/)k g 69c across a resistor always reads less than the actual voltage across the resistor when the metec/ kel))96gnznafmg *r is not present. Explain.

A small battery-operated flashlight requires a single 1.5-V battery. Thegpx:/ , nc8vfl :gly7o bulb is barely glowing, but when you take the battery out and check it with a ogny/clp8:lv,7f:x gvoltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an inter*w.0y5;kq5pl8na7 , li o bbk s;tar4u (mqeetnal 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 resistanceo/s1,ub; fej 1*bvy.ej fggy :,ctd1h 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 viqc b( c)e;4v.ktho: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 havhv6,x/l- vg )dg/dxmde 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 emepibo6 90+ 7cq*tgrfff of $12.0\,V$ 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 serop 4vm.w1nf1n e0mrx(*:i qczies 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 connecpkb y6774n;r :fkmj bxted in parallel to a $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?
$V_R $ =    $\Omega$
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 reveals that m pd;8dnl(;b9 fpjbabr*2i1g.is(x ra $480-\Omega$ 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 qualitatively: fyjer;,.2ojfw:l qs- lj :r2fq -jwes; yfo.,
(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 circu zpy:0loemk e fw/t)j3f s)40qit connected to the battery in (Fig. Below)? Each pol:zf e0q3em)tfs4 k/) j0wy resistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a batter 2or ,ntz(ioac5 i/)nhy as shown in (Fig. Below). Qualita ,innri)c25 taoo(/ zhtively, 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 8g 9 5u9keghlvof (Fig. Below) and show that the sum of all the voltage changes around the circuit i9legu98 vhg 5ks zero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal voltage of eag x8 0o.bs+dgich battery in (Fig. Below). 18V battery =    V 12V battery =    V

  (a) What is the potential difference between points a and d in (Fig. Below ak+n s(oogd0 dyt -iy49q op(k7) (same circuit ak +4dito-0ysqoy(7g(kd op9 n s Fig. Below b, ), $V_{ad}$    V
(b) what is the terminal voltage of each battery?
80V battery =    V
45V battery =    V

a
b

  For the circuit shown in (Fig. Beloneqe(1j /lqxs18i4 sew), find the potential difference between points a and b. Each resistor hasel1e4s xj8qsi/eqn( 1 $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and 7ewr,v,7ofj u directions 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, no67j fv6aji3k mw assuming that each battery has an internal resistance $r\,=\,1.2\Omega$.
$I_1$ $\approx$    A  ----待选择----leftright (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftright  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftright  (retain two decimal places)

  Determine the magnitudes and directions of the currents in each resistor shown 5,3u cm*qnhjn t rd3c.in (Fig. Below). The batncjt*nhq5rdu3cm3, . teries 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 resisavz 4- 2q1 u(cdwvf(sntance $r\,=\,1.0\Omega$.
$I_1$ $\approx$    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 resist ,1(omld qjmppc6 65hmor of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curvwd w*. 0ao19 pivnu:irents $I_1$,$I_2$, 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 curren0d8*bafc8wt 8: up tjnt $I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, ;)rw i9vziln ).gyvc-with unequal emfs of 2.00 V and 3.00 V, are connected as shown in (Fig 9wlczg. r;vvy-)iin). Below). If each internal resistance is $r\,=\,0.100\Omega$ and $R\,=\,4.00\Omega$, what is the voltage across the resistor R? $V_R$ $\approx$    V (retain two decimal places)

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

  You have three capacitors, of capacitance 3200 pF, 7500 pF, and /cgzfs 0 alhwa n0sp+)j94-i x$0.0100\mu F$ . 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 wholej*jsw5ues, vwi 7up j9sv)3h, network of (Fig. Below), calculate the voltage acro jsv u,j 93jes sp5i,wuv)w*h7ss each capacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of a circuit is to be reduced from 4800 pF te: w9ko2zqz kqc* /l iutkh-; (p,ktz-o 2900 pF.cezhk,p :9zioq -l2wq /ut z-; *(kktk
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 jy /f45hpk os3constructed 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 circuir wst x, m hx)5xjhk/*i+mr:(rt shown in (Fig. Below).

  In (Fig. Below), if 4:r fw4vxnxae+;rsj5 j ink /8$C_1=C_2=2C_3=22.6\mu F$, 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), supposeaaisy.a n499yq inx: ,*zim.k $C_1=C_2=2C_3=16.0\mu F$, 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), letbp7vu 7i5t: xb62uqyp $V\,=\,78V$ and $C_1=C_2=2C_3=7.2\mu F$. How much energy is stored in the capacitor network?    $ \times10^{-2 }\;J$

  A $0.40-\mu F$ and a $0.60-\mu F$ capacitor are connected in series to a 9.0-V battery. Calculate
(a) the potential difference across each capacitor,
$V_1$ =    V
$V_2$ =    V
(b) the charge on each. $Q_1$ =    $ \times10^{-6 }\;C$
(c) Repeat parts (a) and (b) assuming the two capacitors are in parallel.
$V_1$ =    V
$V_2$ =    V
$Q_1$ =    $ \times10^{-6 }\;C$
$Q_2$ =    $ \times10^{-6 }\;C$

Three conducting plates, each of area A, arb h5 :5mks 8bgwdc;s6dnm 0h.ve connected as shown in (Fig. Below). vm bs.h8kd65w:mh gn; ds05 cb
(a) Are the two capacitors formed connected in series or in parallel?
(b) Determine C as a function of $d_1$,$d_2$, and A. Assume $d_1+d_2$ is much less than the dimensions of the plates.

  A circuit contains a single 250-pF capacitor hooked acrolfv0u.-o3a )c1 npts uss a battery. It is desired-1ofpu lta)0.v 3cun s to store three times as much energy in a combination of two capacitors by adding a single capacitor to this one.
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is connected in series with an unknown capacitance, and as fg7i2 x9pm f pq* 8iiqs b0im25)rwxt+a series combination they are connected to a battery with an emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its platexfixm2sfr igmi p 9)2qwq 5t+0i78*pbs, what is the unknown capacitance?    pF

  Electrocardiographs are often*;5mymkg anh96ho1p y connected 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 changes in potentihap;5 1yon*69kghm my al 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 fb,oox8 j.(r ais $15.0k\Omega$, and the battery’s emf is 24.0 V. If the time constant is measured to be $35.0\mu s$, calculate
(a) the total capacitance of the circuit    $ \times10^{-9 }\;F$
(b) the time it takes for the voltage across the resistor to reach 16.0 V after the switch is closed.    $ \times10^{-5 }\;s$

a
b

  The RC circuit of Fig. Below a (same as Fig. Below b) hask sb28 ms**h(0pxje vc $R\,=\,6.7k\Omega$ 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 arranged as show hl*bnk+s;qmqztetq. 11 /bu,n in (Fig. Below). Then a potential difference of 24 V is applied across;lqtts+n1 qm,q h 1u./kbb*ze 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 250-V kgy hohc6 ku;3f.sjman t p5cb8(451p scale if the meter sensitivity fkb5c(k aum 4cn16o;3 hjphs8.g5 pty is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivity of )oc k-xwwro fa*;fl+ 3$20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resista 4al1shqf):hk+p52skkr na3k) aql e4nce 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 sensivta lv :vfr65lj9 5sd1v 0pzo,tivity 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 fullxhorvnn-oi0a(*z. (gm 62k sg scale. It consists of a $0.20-\Omega$ resistor in parallel with a $33-\Omega$ galvanometer. How can you change this ammeter to a voltmeter giving a full-scale reading of 10 V without taking the ammeter apart? What will be the sensitivity ($\Omega/V$) of your voltmeter?
$R_{ser}$ $\approx$    $\Omega$(Round to the nearest integer)
The sensitivity is    $\Omega/V$

  A 45-V battery of negligible interna.j u fg-oq5ismx,q4 /kl 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 resistance9ba0pah i:3p9n, j j rj2tggv3 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 thecq s mppv2x/k7vgf/1 fip8w3 * voltmeter of Example 19–15 have to be in erro 7csv*ivwqkmpp 2fp8g/1 x f/3r by less than 3%? $\approx$    k$\Omega$

  When the resistor R in qlx /q v 5fw19nh)4( /kd ep-tuug(fuw(Fig. Below) is $35\Omega$, the high-resistance voltmeter reads 9.7 V. When R is replaced by a $9.0-k\Omega$ resistor, the voltmeter reading drops to 8.1 V. What are the emf and internal resistance of the battery?
r $\approx$    $\Omega$(retain one decimal places)
$\varepsilon$ $\approx$   V(retain one decimal places)

  Suppose that you wish to apply a 0.2)*krv-gwy0iw wo0g1/wevezr (2j t e63pn5 hm5-V potential difference between two points on the human body0w /i1rwyn0jv * (wove rew 265ktpmg)eh-3gz. The resistance is about $2000\Omega$, and you only have a 9.0-V battery. How can you connect up one or more resistors to produce the desired voltage?    k$\Omega$

  A three-way lightbulb can produce 50 W, 100 W, or 15ig kof+q,7x;eac .z.g 0 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually or i z+7,fceo.gk i a.xg;qn 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 appapk7ovj; e ndj, qojn:e2a4 e9*ratus that is 95 m from an electric outlet. Each of the wires connecting you4p9jk aj2:, jo*q;evnndo7ee r apparatus to the 120-V source has a resistance per unit length of $0.0065\Omega/m$. If your apparatus draws 3.0 A, what will be the voltage drop across the connecting wires and what voltage will be applied to your apparatus?
$V_{wires}$    V
the voltage applied to the apparatus is $\approx$    V(Round to the nearest integer)

  Electricity can be a hazard in hospitals, particularly to patients who 1j ne4:ojp8 *i bwipy5are 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 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 t y:pi4jb8wo1p j*en 5ihrough the patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must a 45-V s+w+,s( .z lpcmriz/zbattery 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 desig*9f xe )ut8nwbfr8 *-yjng l*aned 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 resis -u/* z06 0vjk qel()mgqdgukhtance 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 circto6bt rtd u:+(8v7aeyuit” used to make measurements of resistance. The unknown re6 :u r7 byt+atdv(8oetsistance to be measured, $R_x$, is placed in the circuit with accurately known resistances $R_1$ ,$R_2$, and $R_3$(Fig. Below). One of these, $R_3$, is a variable resistor which is adjusted so that when the switch is closed momentarily, the ammeter Ann Meter shows zero current flow.
(a) Determine $R_x$ in terms of $R_1$ ,$R_2$, and $R_3$.
(b) If a Wheatstone bridge is “balanced” when $R_1\,=\,630\Omega$,$R_2\,=\,972\Omega$, and $R_3\,=\,42.6\Omega$, what is the value of the unknown resistance?    $\Omega$

  An unknown length of platinum wire 0.920 mm in diameter is placed as the unknolz yq d.cy.l;m p*89q+t8x fktwn resistance in a Wheatstone bridge (s.8l dyzl mpk+;q*y9c.tq8 fxtee 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 bbvn e9m+drtc/ 40 ,mbx0tu8 wae obtained by connecting four identicv4wtxe 90c 80nm/bburt+m a,dal capacitors, each having a capacitance C?

  The variable capacitance of an old radio tuner consihd egb/nd35,4bl3c voj +av 1psts of four plates connected together placed alternately between four other plates, also connected together (Fig. Below). Each plate is separated from its neighbor by 1.5 mm of air. One set of plates can move so that the area of overlap of each plate vaeh/ogb5a 1v3pd+,3 lvjdc4b nries 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 2.20 A isomj:9hz0cilb ,zouu p 87 )(bq drawn. What are the emf u:h,0loum7p(zz)9c oj8q biband internal resistance of the battery?
r =    $\Omega$
$\varepsilon$ =    V

  How many $\frac{1}{2}-W$ resistors, each of the same resistance, must be used to produce an equivalent $2.2-k\Omega$, $3.5-W$ resistor?    $\Omega$ resistors, each rated at ½ W, in  ----待选择----seriesparallel 
What is the resistance of each, and how must they be connected? Do not exceed $P\,=\,\frac{1}{2}W$ in each resistor.    k$\Omega$ resistors, each rated at ½ W, in  ----待选择----seriesparallel 

  The current through thn 8hh f6g:c4jj7lmx.ad o19ku 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 capacitor has capacigiy qkg5z 4ukgfk) 04z9 sr;y(eco 4/utance $C_0$. 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 shownyp84, koee(tn in(Fig. Below), 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,ju. p4uy0ioa 3 has an output of 350 mA at 0.80 V when exposed to full sunlight. A solar panel that delivers close to 1.io a34pu .uj0y0 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 outp l -zypw(uki4c199l8/0 ouy3yd xexozut voltage of 12.0 V, but you need $V_T\,=\,3.0V$ for an experiment.
(a) Using the voltage divider shown in (Fig. Below), what should $R_2$ be if $R_1$ is $10.0\Omega$? $\approx$    $\Omega$(retain one decimal places)
(b) What will the terminal voltage $V_T$ be if you connect a load to the 3.0-V terminal, assuming the load has a resistance of $7.0\Omega$? $\approx$    V(retain one decimal places)

  The circuit shown in (Fig. Below a) uses a neon-filled tube as g8q n lu+or*9nin (Fig. Below b). This neon lamp has a thre o8l*nng+r qu9shold 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 thv y-m e-f ly/(vccg34ce $20-\Omega$ 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 i)fice;w3qg( x n (Fig. Below), the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance (bnqvz/ (uay,yn;jhprn 3 l,5ek:x8aof 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 as shown in (Figqt 10d )b)dkpu. Below a) to measure a resistance R. If V is the voltmqu) d0d1 kp)bteter reading, and I is the ammeter reading, the value of R will not quite be $V/I$ (as in Ohm’s law) because some of the current actually goes through the voltmeter. Show that the actual value of R is given by
$\frac{1}{R}=\frac{I}{V}-\frac{1}{R_\mathrm{V}}$,
where $R_V$ is the voltmeter resistance. Note that $R\approx V/I\quad\mathrm{if}\quad R_\mathrm{V}\gg R$ .
(b) A voltmeter and an ammeter can also be connected as shown in (Fig. Below b) to measure a resistance R. Show in this case that
$R=\frac{V}{I}-R_\mathrm{A},$
where V and I are the voltmeter and ammeter readings and $R_A$ is the resistance of the ammeter. Note that $R_\mathrm{A}\quad\mathrm{if}\quad R\approx V/I\quad\mathrm{if}\quad
R_\mathrm{A}\ll R.$

  A flash lightbulb rated at 2.5 W and 3.0 V is operated by a 9.0-V battery. To l0..i0w nno qw6qgdpdve54y*a ight the bulb at its rated voltage and power, a resistor R is connected in .*0.o5v60 wdnyqw da4iq nepg series as shown in (Fig. Below). What value should the resistor have?    $\Omega$