Explain why birds can sit on power lines saog, mdb 4x8f9gfely, whereas leaning a metal ladder up against a power line to fetch a stuck kited f9bmx 84ogg, is extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree lx.mu uj1qe n7jx.1 8nwights connected in parallel versus those connectn7j8. ju1em.1 xwxq uned in series.

If all you have is a 120-V line, would it be possible to light severe5r*fc- rih c)al 6-V lamps w)irr c5fhe*c-ithout burning them out? How?

Two lightbulbs of resistanco:jyr fq 8cc1.e $R_1$ 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. Ar2;pru i0*k4hprv) nlu e these connected in series or parallel? How do you knop*uip0;k) rln uhr 24vw?

With two identical lightbu8tyqu qo6wo b+i dr.(-ef60 m.u *utaolbs and two identical batteries, how would you arrange the bulbs and batteries in a 8u- mqa6de6itq. oot+u(ry.fb*uow0 circuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors ar 0 z9lr: siszb/ii3ef uyt/4r1e connected in series to a battery, does the battery have to supply more power or less power than when only one of the resistors ty/zurils ifb 9 4/isez0r31:is connected? Explain.

You have a single 60-W bulb on in your room. How does the overall)d hx /lu:)dva resistance of your room’s electric circuit change when you turn odla/)x:ud vh )n an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in/:7 efwb6g nbd Fig. Below), does the sign (or direction) of a battery’s emf depend on the direction of ndgb7: w/6e bfcurrent through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use tx3pa7 .y y9yyrhe words “increases,” “decreases,” or “stays the same” to comr. x3yyyya p79plete 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 i3 vo ovc zj0gp5kik04;ozcu(.n series? For what use are they connected in parallel? Does it matter if the batteries are n4p(oog5;cjuzz3 vk kvco.i00 early identical or not in either case?

Can the terminal voltage of a battemi(mafxz( xh2),zopw z s-,: nry ever exceed its emf? Explain.

Explain in detail how you could measureqti x8f2(n5(6gt ipdr the internal resistance of a battery.

Compare and discuss the formulas for resistors and for capacitors whrdiz 6m 4*f*rhen connected in series and in rz md6r *h*if4parallel.

Suppose that three identical capaci pwtuitgb w ;7;s,mu)e5 xi5p3tors are connected to a battery. Will they store more energy if connected in series ormw;7w3i5 bs ig )t,5etpupu ;x in parallel?

Why is it more dangerouy:td; +yjojk ahr* u/+rvci9* s to turn on an electric appliance when you are standing outside in bare feet than when you are inside wearing shoeakjh:*o+rc tr; *dj9u yy/+ivs with thick soles?

(Fig. Below) is a diagram of a capacitoc nj;zdhs s+dr49k:+wr (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 a current of the same frequency as the sound wave is pwd+nj+cr 94h :;sk dszroduced.

Design a circuit in which two diffe( e k* orn4+a0y1gruuerent switches of the type shown in (Fig. Below) can be used to operate the same lightbulb from oppos0r4o ne +1a gr(ek*yuuite sides of a room.

In an RC circuit, current flows from the battery untilwvku/i2zc q gqo728n / the capacitor is completely charged. Is the total energy sug7c// 2izqk uqv8n2o wpplied by the battery equal to the total energy stored by the capacitor? If not, where does the extra energy go?

What is the main differ8onlkusc po2-0l8v t) c-o7 pqp;uzfz)k0r1hence between an analog voltmeter and an analog ammeter?

What would happen if y6b8sqt hoc9qo1: esbx/-1avjr o xm* /ou mistakenly used an ammeter where you needed to use a volte 1s/ v8*m :6c1qbohxtr b-qsaxj9o/ometer?

Explain why an ideal ammeter would have zero ra27405hl x8 pb pvu rgj3bg7itesistance and an ideal voltmeter infinite re2 7brbpag0 43lhv8g5 xu7tjip sistance.

A voltmeter connected c s gtsg*+oqn,k:y: 7aacross a resistor always reads less than the actual voltage across the resistor when the meter is not present. Explain.,n7 *+:ct:s qgyo sgak

A small battery-operated flashlight requires a single 1.5-V battery.bsr nn triurx+v5-697 fvqz74 The bulb is barely glowing, but when you tqb-rsv+9t4 zruf76 v57xr innake the battery out and check it with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an inter 9gyr;vusdhr yj 3zaqv-k2 9+(nal 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 resis*it;h r nj91x1t,o.v+q /o8g evor owmtance 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 haveps; fmn,xmt87 7kb6h g a $680-\Omega$, a $940-\Omega$ and a $1.20-k\Omega$ resistor. What is
(a) the maximum,    $\Omega$
(b) the minimum resistance you can obtain by combining these?    $\Omega$

Suppose that you have a mq;vrhogx0x-7 ; m7.8(/ yuaoxmzzxb$6.0-V$ 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 ofz 6vgx-lj: 2gm $12.0\,V$ 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 connectafnpoea2( d6:dbt s 6.ed 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 a gp8y hv/c57bw $110-V$ 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 aq)vc1za: 2d8d /f ozran electric circuit 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 resi-uo n5gf 0u(oestors shown in (Fig. Below). Answer qualitatively: fn 0o(5e-oguu
(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 bat88i). y e j9l1wnfiuwutery in (Fig. Below)? Each reu9jly w8ni).ui 1ef8wsistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connd38t l-ltrd- 92pakia ected to a battery as shown in (Fig. Below). Qualitatively, what hdl-kt r8a l 29tpad3i-appens 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 jmykrc/q fyw: yd.6,zix1 a+imw *i.6that the sum of all the voltage changes around the circuit is ze1iyi:.6ca,kwfi+m.6yyx wqz d jr*m/ ro.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each2v8kd q;wug xp*nl-.h battery in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential difference b bc,w1cg zg6q;etween points a and d in (Fig. Below a) (same circuit1gg ,zwc6 c;qb 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 (F8.e1iaq whkfa (-ea b)ig. Below), find the potential difference between poinha aea.fw) 1q (eb8-kits a and b. Each resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of thgt*;g,kc q /jhe currents through $R_1$ and $R_2$ in (Fig. Below). $I_1$    A  ----待选择----leftright  $I_2$    A  ----待选择----leftright 

  Repeat Problem 27, now assuming that each bs w:qe:j +apy2fzysxbqg9, 3-s:sb )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 current.p2y oc)tzmgk iz 1-q1s in each resistor shown in (Fig. Below). The batteries have -1y zo1gz m2)kcqi .tpemfs 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 ew6h ilzrk yf14cb. 3t6ach battery has internal resistance $r\,=\,1.0\Omega$.
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Calculate the currents in 0w6mnnkhxa .l xay.*)each resistor of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currtkk wtdyp61h9; o:hc .ents $I_1$,$I_2$, 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*41w 40sk(8gye(m tlfm.ed.l dljfgm $I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, with unequal emfs of 2.00 V and 3.00 V, are connected am6eyheqlqzl25fo0 jlw * 6 p7)l6 2gyxs shown in (Fig. Below). If each internaj m ygewlzy7lqo6xh2*ll60ep265 )qfl 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,ucg2n2nfl ;aa+k l. /fgwy y-d3,m2bm 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 -c 5ft;kk,kwa across the whole network of (Fig. Below), calculate the voltage across ea f,;-wa5kctkk ch 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 to 237sjve7v:ha bb6i.od3iz )t/8xwshb900 pF. 7hosz3 ivh)ia w/xbt63d 8jb7v.:ebs
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 using a v0(h5 a)upl ad$5.0-\mu F$ capacitor instead of the required $16-\mu F$ value. Without removing the $5.0-\mu F$ capacitor, what can a technician add to correct this circuit?    $\mu F$ conneected in  ----待选择----parallelseries 

Determine the equivalent capacitance of the circuit shown in (Fig. Belowi9ju u j (30nii(ib8or).

  In (Fig. Below), if eona,9umgw25 $C_1=C_2=2C_3=22.6\mu F$, 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), suppo(;wjgu z 3zh)drq6 1jcse $C_1=C_2=2C_3=16.0\mu F$, 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 3 3ntld3x9vu)(kb t/yuxm w g2$V\,=\,78V$ 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, are connected as shown in b lwyae:iroc*m7 y1 u a6m7tg:f/t6x;(Fig. Below).r ymm*ca76yi:gwt x/utfb: e17a; ol6
(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 across a battery. It is iwecklxy 930 )f-(qy.m ckuz,desired to store three times as yiq.k9mzk w3u) x0(fccyl-, emuch 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, an-(z)6ez6h0w 2t)qw ab ur iqlkd as a series combination they are connected to 6wbq r2kwzlq()-z)u t ie06ha a battery with an emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often w7 ri7 zc 6:v0s;mprefconnected 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 is 70pzfc; wvmire67r :n 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. xj:4zbh rr-8v 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 b)ypz+u) -ixsam:tpdz4s o 66x1 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 arranged as shown in (Fig. B64n amzgyc83h + u5 f/2jcqbdaelow). Then a potential difference of 24 V is applied across thdh 8u4ybcmfz 2 6a3gnq+ca/j5 e 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-Vs.n hs6 at88zf scale if the meter sensitivity is s8hz at n8fs.6$30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensy:f y a6s1uwyo; la.a5itivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an interyxfc c m ghpi(*i)c,82ex ,8pdnal 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 sensitig).vn zuw9r r(l8- 6cahcz 5 ilwvwl.+vity 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 ytwhc ae )dd(**5x,ky w0tln5 mA full 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 connectk3xlyt2gjnt2 xgw80c,d. w3;ubp2pl ed 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 resistancy:7walr-f a;m e is $63\Omega$ reads 5.25 mA when connected in a circuit containing a battery and two resistors in series whose values are $750\Omega$ and $480\Omega$. What is the actual current when the ammeter is absent?    $ \times10^{ -3}\;A$

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

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

  What internal resistance should the voltmeter of Example 19–15 have to be in er0 rriqet g12s9ror1 rr20q9si tge by less than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) isufd6sd yb.;4 5n0bs+ i;hh epu $35\Omega$, 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 potevrrg) +g1/klw ntial difference between two points on the human body. The resistance is ag r grk1v+w/l)bout $2000\Omega$, 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 product0bs aya;oszx; / 9 d9qtz).tce 50 W, 100 W, or 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually /0bxoza ytd9szaq)9 .t c; ts;or in parallel.
(a) Describe how the connections to the two filaments are made to give each of the three wattages.
50 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
100 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
150 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
(b) What must be the resistance of each filament?
$R_{50W}$    $\Omega$
$R_{100W}$    $\Omega$

  Suppose you want to run some apparatus tha61n d7xl*g 9qnm+ln4ych v2bnt is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 120-V source has a resisthdnln1lgb7m c*y9+ 462qnx v nance 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, partipey.0c fx2 rh)cularly 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 (orxfp. )h0r 2yec was not there in the first place). If a nurse touches the bed and the patient at the same time, she becomes a conductor and a complete circuit can be made through the patient to ground through the ECG apparatus. This is shown schematically in Fig. 19–60. Calculate the current through the patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must a 45-V bg94dx 0bh2;u xanl.rqattery 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 bezr(, k:cws *vpats/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 byosl1- a*o ,mzody 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 cirxkfw/h* /t qz*s-raruy: c9f/cuit” used to make measurements of resistance. The unknown resistance to f*hx-f*tqr://k zr /w ca9suybe 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 ofu5c:,*oqu h1wv5pjt f platinum wire 0.920 mm in diameter is placed as the unknown resistanceuphqu:wj1 5c5* o ,vft in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 have resistance of $38.0\Omega$ and $46.0\Omega$ respectively. Balance is achieved when $R_3$ is $3.48\Omega$ How long is the platinum wire?    m

What are the values of effective capacitance which car11vy 0o :q yx87 rdd6c.weohkn be obtained by connecting four identica 1rho k: q6ywdcrvey 0ox7d1.8l capacitors, each having a capacitance C?

  The variable capacitance of an old radio tuner consists of four plates connect.i rman,4mo.sy 7iw*med 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 i o*.4ysr 7mm ,ia.wmnplates 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 draw 3:ydy ai.hcs(n from it and 47.3 V when 2.20 A is drawn. What are the emf and internal res:acy y.i (3dhsistance 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 thk-n7ulw: 5lbee $4.0-k\Omega$ 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-platem98 5)q t li*e6rbff+fwjdy4x capacitor has capacitance $C_0$. If two identically sized dielectric slabs of dielectric constants $K_1$ and $K_2$ are inserted as shown in Fig. 19–64, what is the new capacitance? [Hint: treat this as two capacitors in combination.]

  For the circuit shown in(Figa)pl- ejk/3 nx. 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, has an ou3,8acdud cenz(kqyzwcm. ac )5 jj,0*tput of 350 mA at 0.80 V when exposed to full sunlight. A solar panel that delivers cloq5 ccyc*d)w,k(3z aj e,m0.j8 duazc nse 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 b:. g:v 71jme;2fyjjmca;axgff/8q bfixed output 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)j 6-;2l2yr mhzyqtg g66gmue ( uses a neon-filled tube as in (Fig. Below b). This neon lamp has a threshold vu r;6qhemytgm 6g2-62(gzyjloltage $V_0$ 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 ep6y3e :jdhnhn6(3pwthe $20-\Omega$ 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. Belapmu jcy.4.1xcgsqh79))t oz ow), the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalen2 c. 6.-f,uemouiwct st resistance 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 ammx w)x:4icuea/r.ks .neter can be connected as shown in (Fig. Below a) to measure a resistance R. If V is the volt:/4urcns a)ke .xx.iw meter 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 operatqbk80unv,c /ned 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).08nq, u vb/ckn What value should the resistor have?    $\Omega$