Explain why birds ca5d6g.+mk pl1rgyuw 3 rn sit on power lines safely, whereas leaning a metal ladder up against a power line to fetch a stuck kite is extremely dangerogpd+l1grm k3w65y r.uus.

Discuss the advantages and disadvantages of Chriu75:zo ysce joy yl50,stmas tree lights connected in parallelyu, 57zl:oy jec5osy0 versus those connected in series.

If all you have is a 120-V line, would it be possible to light several 6-V lameh9 s ill,su,+ps without b,l s sile,+9uhurning them out? How?

Two lightbulbs of resistancf dpcf w:xcqe;90n (qqsl(4x/1 24qykrmb j. ke $R_1$ 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 th64jz5g a*vgff4q tz+hese connected in series or parallh6z*aj gfzg+ vt544fq el? How do you know?

With two identical lighco,o l*a )fpb;nsj rv 2+jm,h)tbulbs and two identical batteries, 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 rpv,+ robmha )jos)*jcf n,;l2 esistance.)

If two identical resist.p xaelykzowwj7/72mn c+4 g,ors are connected in series to a battery, does the battery have to supply more power or less power tha,m/zykgc+. jnelxw w 7a2 po74n when only one of the resistors is connected? Explain.

You have a single 60-W bulb omaravs/:4urll./ teu d)/m) yn in your room. How does the overall resistance of your room’s electritms 4e/ r:ru)mvl )/y/ la.duac circuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (dejn15jb96w7 el. t lusuch as in Fig. Below), does the sign (or direction) of a battery’s emf depend on the direction of current through the battery? What about the terminal voltage? el5 u9jednl6t1bjw.7

  Given the circuit shown in Fig. 19–36, use the words “increases,”j+xb7 5lata(ezg a) b9 “decreases,” or “stays the same” to comp(jebx759t b zalaa+g )lete 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 seriepk9dgfj 06c, :tep b6rs? For what use are they connected in parallel? Does it matter if the batteries are ,ppr c6e0:j6d b9tfkg nearly identical or not in either case?

Can the terminal voltage of a-6ncbmr z yx. o6a,.kjw- tkc/ battery ever exceed its emf? Explain.

Explain in detail how you could measureno0)e ij;hc+ *.sjtjc the internal resistance of a battery.

Compare and discuss the formulas for resistors and for capacitors when connectmpec w.9ocsu.h 4g+ ,ied in series and inm,w+9ho.c.sue ic4pg parallel.

Suppose that three idengmac3jbigo(: 5eh5 t r,kqisv3nb4*6 tical capacitors are connected to a battery. Will they store more encn5bor4: giaeq3( b3 5k ,hmgsi 6j*tvergy if connected in series or in parallel?

Why is it more dangerous to turn on an electric appliance 21td,/j9hgic 1b*spdwhndj k5lh:9 m when you are standing outside ipj1d n*ds5 9/2dwmhlj hct9k,ig b:1 hn bare feet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram b9 c/er p3db2*g/uc :9 a; dngo:rhildof a capacitor (or condenser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to move back and forth. Explain how a2gd/ d*c dgc9uan b prir9b;oe3 ::hl/ current of the same frequency as the sound wave is produced.

Design a circuit in which twxy+ue3vh r ym l,v-9r)sx-dc8o different switches of the type shown in (Fig. Below) can be used to operate the same lightbulb from opposite si9-3mxvr -,u+r8svyleh x)cy ddes of a room.

In an RC circuit, current flows from the bat; g 21x(dsyt;dbordkyrqv /(v7m.6wbtery until the capacitor is completely charged. Is the total energy supplied rsm6x/ gqvd r ;b(d7.y(v1;dko byw2tby the battery equal to the total energy stored by the capacitor? If not, where does the extra energy go?

What is the main difference between an analog voltmeter and an;jvc1)ns0 p:t;:et+1y q o1ja yklwsx analog ammeter?

What would happen if you mistakenly used an ammeter where you needed to use a vezjg0wk n ji;+,aes0+oltmwa+n0 jg0ej,sik;+ z eeter?

Explain why an ideal ammeter would have zero resistance and aab u.,*ohs2;x 6,pclntt/cms n ideal voltmeter infinitsn h* ca ctbpl ,ts2muo/,.6x;e resistance.

A voltmeter connected across a resi5hcqg 2.t bb3 n1:yvrrstor always reads less than the actual voltage across the resistor when the meter is not present.c3bh r5q.byv 1n2:rtg Explain.

A small battery-operated flashlight requires a single 1.5-V bbygu9l 5yl4i(attery. The bulb is barely glowing, but when you take the battery out and check 4u y 5bl(gl9iyit with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal volwoajse s (:z +)7, s(bmpbq(bmtage 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 resistanceo7g johm/pkqr85 *u 6e of a $12.0-V$ car battery whose terminal voltage drops to $8.4\,V$
when the starter draws $75\,A$?    $\Omega$
What is the resistance of the starter?    $\Omega$

  A $1.5-V$ dry cell can be tested by connecting it to a low-resistance ammeter. It should be able to supply at least $22\,A$. What is the internal resistance of the cell in this case, assuming it is much greater than that of the ammeter?    $\Omega$

  Four $240-\Omega$ lightbulbs are connected in series.
What is the total resistance of the circuit?    $\Omega$
What is their resistance if they are connected in parallel?    $\Omega$

  Three $45-\Omega$ lightbulbs and three $75-\Omega$ lightbulbs are connected in series.
(a) What is the total resistance of the circuit?    $\Omega$
(b) What is their resistance if all six are wired in parallel?    $\Omega$

  A $650-\Omega$ and a $2200-\Omega$ resistor are connected in series with a $12-V$ battery. What is the voltage across the $2200-\Omega$ resistor?    V

  Given only one $25-\Omega$ and one $35-\Omega$ resistor, list all possible values of resistance that can be obtained.    $\Omega$    $\Omega$    $\Omega$    $\Omega$

  Suppose that you have a z+i9z0xa3*. a ieuja z$680-\Omega$, 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 havutb7 )ph*)ts2 u4b trae 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 ud,c2*w gd/b; ix m*bpof $12.0\,V$ 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 connec(qc hc*a7d:d gted 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 parallel to zz)o 4uzvj0 eb a;65dpa $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?$V_R $    $\Omega$   

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

  A close inspection of an electric circuit reveals that a libd:n5up5 y1$480-\Omega$ 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. Below60asn snl3w( qkls e 2x7cov(+). Answer qualitatively: 7a2c 3nv6s0s((+wxn qsleo kl
(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 battery in (Fy zv rmtkh;-i (+*-osu8tx5 qfig. Below)? Each resimikor qzy;sv-fx+hu 8t- ( *t5stance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown in (Fig. Below)z;)ewdj n, fk.l y1tc2. Qualitatively, what 1z)w fletk 2c,jy nd;.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) and show that the sum nta0 y) dq59kjof all t aj0q k5t9y)dnhe voltage changes around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each batt3zsakdm:f:8 t ery in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential difference between points a and d in (Fig. Bevph-m( h:*azhlow a) (samzh *hpv:m-h (ae circuit as 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. Below3ufm r/yr: kw-; im*sxis5hzj/1la q3 ), find the potential difference between points a and b. E5mi/*rk3mi-:f/l3rz s; yx js1waqhu ach resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the currents tj1m* efd 9/pxshrough $R_1$ 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 ftp 9gfd/(i 3(7ix :t lp-efeuhas 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 showaf(gq 7-9fb zan in (Fig. Beqagbf 9( f7-zalow). The batteries 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 q27o9 o8g kawc$r\,=\,1.0\Omega$.
$I_1$ $\approx$    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 resixwe;k8 f5d1 6alh5i*vi bkrm 1stor of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currentt)qh6by6 fg1i9 q 5clgs $I_1$,$I_2$, 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 z.(2 ctz vcj/i$I_1$ 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 emfs4r)9 a8ek(lc:ms oqqp of 2.00 V and 3.00 V, are connected as shown in (Fig. Below). If each internal r)sc94(re p ko:maq8lq esistance 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/;za daw :eru* 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 (Figav7 rn xko+2 /zxbo7b-. Below), calculate the voltage across each n -7zv/o+ xab7kbo2rx capacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of a circuit is to be r64 law80uwarw ;t l3k0smlu1ieduced from 4800 pF to 2900 pF. k3m6 w4rl; 8sua0twl ulia w10
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 constructed usixg:vfvt -2e )xng 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 capacitanq r0tl2/.wv+t )x7xknj2lal3bo fpd/wyn .0z ce of the circuit shown in (Fig. Below).

  In (Fig. Below), if 76;gagus6 l n.aiju-v$C_1=C_2=2C_3=22.6\mu F$, 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), sup5xd f0-ov9a i:slul, rpose $C_1=C_2=2C_3=16.0\mu F$, 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), letj (iqyj-/n(m(3v4af9 kwki c m $V\,=\,78V$ 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 oepza b*fu 0m0+f area A, are connected as shown in (Fig. Below).azu+m f*0pbe0
(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 agf mr+52k sxjx.r.rz6 single 250-pF capacitor hooked across a battery. It is desired to store three timrgsjk zrrx2.+.6f5 mxes 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 fiukx mf1d 8yxllpqu;9+ev 9-.z8a /za 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 pla9lz8x9mzx y/u;+.e- fdai vp8lk1fq utes, what is the unknown capacitance?    pF

  Electrocardiographs are often connec xv9c+r, npjz6ted 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 changesc9, zj+6pxnr v 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 qsw )yf ,hyb69z*o3xc. Below b), the total resistance is $15.0k\Omega$, and the battery’s emf is 24.0 V. If the time constant is measured to be $35.0\mu s$, calculate
(a) the total capacitance of the circuit    $ \times10^{-9 }\;F$
(b) the time it takes for the voltage across the resistor to reach 16.0 V after the switch is closed.    $ \times10^{-5 }\;s$

a
b

  The RC circuit of Fig. Below a (same as Fig. Below-q)f- -xrtwp/f4tosp 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 arx8t0b q-qzp-v ranged as shown in (Fig. Below). Then a potential difference of 24 V is applied a0q -t-px8qzvbcross 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 scalla8a2jzaj,:ah- tv 8t f6u2nve if the meter sensitivity izhl fj, -u2v:8t6anta2vja 8 as $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitiv +/q-bs 8mk;ui/au q/mwlzk:uity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an interyaomx/- c7tuaoy3 (b )nal 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 ryefga )dfiz6k1 n;;xx(:/ppsensitivity 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 fullg 2c atr zo bpxq5p)31b9ups() 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 internal resistance is i7s62mnmo ojown) +flr +j (b8connected 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 internabmg.q m1x+yu:l resistance 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 resistanc3w2r5b4uvz h ltsmn/ +e should the voltmeter of Example 19–15 have to be in error by leunt25 w/rmh+lz3sbv4 ss than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) istq e k,qkeg+g6c c(,+1( fo7m gz1racc $35\Omega$, the high-resistance voltmeter reads 9.7 V. When R is replaced by a $9.0-k\Omega$ resistor, the voltmeter reading drops to 8.1 V. What are the emf and internal resistance of the battery?
r $\approx$    $\Omega$(retain one decimal places)
$\varepsilon$ $\approx$   V(retain one decimal places)

  Suppose that you wish to apply a 0.25-V potential difference betwee4h mjbt+i7ux1d :1uuu n two points on the human body. Thi7+1mb ut1ju4:uxd uh e 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 150 W, at 120 V. . 2wsg/qjsd2*q be1bm Such a bulb contains two filaments that can be con*s2mwd.bb qg12j e/s qnected 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 apparat3dkib3:t d -sltp* sd-us that is 95 m from an electric outlet. Each of the wires cttdl-sds 33dk: - bi*ponnecting your 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, particularlyz-)(oany.p; vm f;.urwcv*ul 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 w -.w*;ua zyn(p cm);olvruvf.as 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 expend4jo b()ony;5culx ia gv6r j;7 to charge a $0.40-\mu F$ and a $0.60-\mu F$ capacitor fully when they are placed
(a) in parallel,    $ \times10^{-3 }\;J$
(b) in series?    $ \times10^{-4 }\;J$
(c) How much charge flowed from the battery in each case?
$Q_a$    $\mu C$
$Q_b$ $\approx$    $\mu C$(Round to the nearest integer)

  A heart pacemaker is designed to operate at 72 beats/min using ali62muarm2vz:fgi *; dili)3 $7.5-\mu F$ 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 resistanmo-n r7umo xv,. ;ho4-vlecw5 gj-6tuce 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 to make measurement 2ko2giiih 3pj*eq7 w(eda12ds of resistance. The unknown resaop hi123i *dk27qeiew (2jdgistance 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 d f+te;noa4 3zunknown resistance in a Wheatstone bridge (see Probl z34dn;t+e oafem 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 obtn3vo,uhd z *t3ained by connecting four identical capacitors, each hn zv3,u3d*o thaving a capacitance C?

  The variable capacitance of an old radio tuner con 44pz* rh(x/ s8mnblzfsists 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 vari (44hrn/fxz*8slpmzb es 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 ando1 4dv k9f 4srtkv wjd;ac+*,d 47.3 V when 2.20 A is drawn. What are the emf and internal resst av 4 ,1o9wjv4 ddkr+fckd;*istance 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 4* oec+fulve; lhz)m8rd7l5i the $4.0-k\Omega$ 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 capacitorh e z+nt6t)e;x 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)no2/+m plx4rrl d3b l2, 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 fd:tuxw 0qf:+m5g(o/ t.x-,hduzlo e 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 to an external log(etud+ 5l/x-:odu :o0f f. zhw,xqmtad 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 of 12.0 V, but you y)zoddt6 pt( (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-fi 9 /9+sv3x.ygecj x +xxtao2helled tube as in (Fig. Below b). This neon lamp has a thr+2 a3ysxx.9 xexe c+tg9hjv/oeshold voltage $V_0$ for conduction, because no current flows until the neon gas in the tube is ionized by a sufficiently strong electric field. Once the threshold voltage is exceeded, the lamp has negligible resistance. The capacitor stores electrical energy, which can be released to flash the lamp. Assume that $C=0.150\mathrm{~}\mu\mathrm{F},R=2.35\times10\mathrm{~}^6\Omega,V_0=90.0\mathrm{~V}$ and Ann meter=105 V
(a) Assuming that the circuit is hooked up to the emf at time $t\,=\,0$, at what time will the light first flash?    s
(b) If the value of R is increased, will the time you found in part (a) increase or decrease?  ----待选择---- increase decrease 
(c) The flashing of the lamp is very brief. Why?
(d) Explain what happens after the lamp flashes for the first time.

a
b

  The current through the xd m,w 5tb4y1l$20-\Omega$ 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. Below5--ok- jsix sp,1ddj nmmqq 45), the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent ret0t,o(pevuz 0 sistance 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 as shown in (Fig((:fv-2wt2qvuj yqz2zmok; e . Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeter reading, the valueuz:jk-z2w eyvq tv(( 2o2;qmf 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 operag3+vxpkdn 8l9 ted by a 9.0-V battery. To light the bulb at its rated voltage and power, a resistor R is connected in series as shown in (Fig. Below). What value should the3nxgkv9 8l dp+ resistor have?    $\Omega$