Explain why birds can sit on po9u23:scvx *mvidoak j-c q .h4wer lines safely, whereas leaning a metal ladder up against a power line to fetch a stum 4 oi vjhuka.c2scdqv *3x:-9ck kite is extremely dangerous.

Discuss the advantages and dish /+7je o;d+p vaq(g1ndw+ x)6yoci vwadvantages of Christmas tree lights connected in paralle+vo(+w gycp ea wijqn ) h/+vd;7ox16dl versus those connected in series.

If all you have is a 12+8 v9wqc0 pxys0-V line, would it be possible to light several 6-V lamps without burning them out? Hwv 0ypscx+ 8q9ow?

Two lightbulbs of resistan-au .:6 s9fesw vkbpw+ce $R_1$ 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 s t (d 0 f zziyycb:t7b5:juxz/e7hj*7outlets. Are these connected in series or parallel? How do 7tby citjfb y jhzx* 775su:z0e(d/: zyou know?

With two identical lightbuljl3c:2kro fq/ 0 wyqz4hs6o 7hugcu)3bs and two identical batteries, how would you arrange the bulbs and batteries in a circuit t7h z )fsuy 2c6jhlor:qw u30/koc3 gq4o get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in skm5f6j6 xy3:rk5it 8/dysjtw eries to a battery, does the battery have to supply more power or less power thandyrk6/f8j i5k sty6 5m3xtjw: when only one of the resistors is connected? Explain.

You have a single 60-W bulb on in yogr5/*shn71xrmetfw wz 9cz20ur room. How does the overall resistance of your room’s electric circuit change whe2/sfcgzr nhxwwt r 0m957e *z1n you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in o3t lfvn/ 8zl+Fig. Below), does the sign (or direction) of a battery’s emf depend on the directiovlnt8 / z3ofl+n of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 14o w3pa6(ul ilofq6 c+9–36, use the words “increases,” “decreases,” or “stays the sq 6a lo3p fiu+owl(4c6ame” 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 serie)xq70m , grszrb f36aps? For what use are they connected in parallel? Does it matter if the batteries are nearly identical or not in eig 7 0,36qp)mraxzrbsf ther case?

Can the terminal voltage of a battery ever exceed io8 e-e +, xj)yasx1q)apqk*pbts emf? Explain.

Explain in detail how you could measure the internal resistann g*(i ;b-dyuvce of a battery.

Compare and discuss the formulas for resistors and for cap q.,f4u: n5.kyhrftglacitors when connected in series and in parallelk5lt, g.q.y frf4 h:un.

Suppose that three identical capacitors are connected to a battery. Will thejhace63o i od1y79m rxaxj. c+3pkd,)y store more energy if connect dc67oo x1a ,ei mp9j3jyx rh.3cd)ka+ed in series or in parallel?

Why is it more dangerous to turn on an electric applia;q t /o2rjvy6dnpy94 qnce when you are standing outside in bare feet than when you are inside weari ty6 qq;jv9/rnpd42yong shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphone. T g(c dwawan*:2g7-7 2o/1u 1zf yblq dvsbmb0vhe changing air pressurea cfbgazov:snd2(w v*7- u/2l1w7d g b 0b1yqm 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 produced.

Design a circuit in which two different switches o adyu8tr ..k(sf the type shown in (Fig. Below) can be used to operate the same lightbulb from o(kyrtd.8.s ua pposite sides of a room.

In an RC circuit, current flows from the battery until the 03ei f *rs6fo:24wr6nieezy c y:f)arcapacitor is completely charged. Is the total energy supplied by the battery equal to the total energy stored by the capacir eofi:es yz6 3ef4)2yrrniw6c* :0fator? If not, where does the extra energy go?

What is the main difference betwck3d +. .tvjomhmt(5;lu+v,okil )o1pu h p- seen an analog voltmeter and an analog ammeter?

What would happen if you mistgx +c w0vn41hm(ul- bb+p f3gxakenly used an ammeter where you needed to use a voltmeter? mb3(h xbn-vp14+gugx wf0lc+

Explain why an ideal ammeter would have zero resistance archg35 iinnix9-8h .*ax 1i. bcg9yswnd an ideal voltmeter infinite resistanceahx1g95 yr - s.b*8c iiwcx9 3nnh.iig.

A voltmeter connected across a resistor alxa q .:z05onmyu bam-:ways reads less than the actual voltage across the resistor wza-m:bxom y.u: a0n q5hen the meter is not present. Explain.

A small battery-operated flashlight rw/y(4nvz /v1 v 5gdsjxequires a single 1.5-V battery. The bulb is barely glowing, but 4j v/1gyv xvd s(w5n/zwhen you take 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 34aat7uj v5auan 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 dver2 .j .k(zpresistance 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 havzibj 38 myos 9kw*il)hsgeiw; qh9091e 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 jz0 1/wcau/7 l9r)j1mav-yzqxakr y 8a $6.0-V$ 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 oivm3,, 4lbyggf $12.0\,V$ shows a terminal voltage of $11.8\,V$ when operating in a circuit with two lightbulbs rated at $3.0\,W$ (at $12.0\,V$) which are connected in parallel. What is the battery’s internal resistance?    $\Omega$

  Eight identical lights are connected in series across sob:wy 7d 46mba $110-V$ 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 as/+dkd++ n ny73bamvq $110-V$ 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 that6 b:88 m1h(uork 70juzsu;khm ito+et a $480-\Omega$ resistor was inadvertently soldered in the place where a $320-\Omega$ resistor is needed. How can this be fixed without removing anything from the existing circuit?    $\Omega$

  Determine
(a) the equivalent resistance of the circuit shown in (Fig. Below),
$R_{eq}$   $\Omega$
$V_{470}$    V
(b) the voltage across each resistor. $V_{parallel}$    V

  A $75-W$, $110-V$ bulb is connected in parallel with a 40-W, 110-V bulb. What is the net resistance?    $\Omega$(Round to the nearest integer)

  Consider the network of resistors shownj* 5y;8pl rogr in (Fig. Below). Answer qualitatively: p; j5ryg*rl 8o
(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 resimp n3-fu1b *xmv xo)7gstance of the circuit connected to the battery in (Fig. Below)? Each resistan7o*x bn)f uxgpmm3v-1 ce 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)b9b fexq.5lijwel/ 1;. Qualitatively, what happb/9e 15xwfjlbl e.iq; ens 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 ci j.zqw,edmx+s,m7* tg rcuit of (Fig. Below) and show that the sum of all the voltage changes around the circuit is 7,q,j e xmgwd+*mzs. tzero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each battery in (Fig.h hj4; iq.iyzzr*ju s (os8(8v Below). 18V battery    V 12V battery    V

  (a) What is the potential diffepy62 d0+asi(p li tt-wrence between points a and d in (Fig. Below a) (same circuit as Fig. Below b, atyw -lpdi+(6 t s02ip), $V_{ad}$    V
(b) what is the terminal voltage of each battery?
80V battery    V
45V battery    V

a
b

  For the circuit shown in (Fig. Below), find the potential difference between po f13prn uxj fdv 1yyr((/z/3lcints a and b. Each resistor hc l(yr/3(1fxy j fv1 /n3zurpdas $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directnx7st)e5; dhg ions 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, now assuming that each battery has an intern4wfax).tnyft:/d ih. o:b6sh t2 c3 fhal 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 magnitudes4 vi ;is* pi1pnjqvl6hf+y3ji p**st3 and directions of the currents in each resistor shown in (Fig. Below). The batteries ha*i l4ijhqpf+pt1 ; y*nvvpi s*jis 336ve 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, assumxwp:hqw. 5ee838jqqzw:f 63s j /nroxing each 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 each resistor of Fig. 1t-uy2pvh j37i9–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the cudw9 2 :o o2 tk5zrfihin;vpq41rrents $I_1$,$I_2$, 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 curreagmoy 4kmy0)u( l *x:lnt $I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, with unequa7 +9qrtns7zp h0v/vfk l emfs of 2.00 V and 3.00 V, are connected as shown in (Fig. Belowf7 7h tznpqv9+0skr/ v). 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 capacitow97nwnu)6qv w0 aq-4ucxno (q sc/gf5rs, of capacitance 3200 pF, 7500 pF, and $0.0100\mu F$ . What maximum and minimum capacitance can you form from these? How do you make the connection in each case?
$C_{max}$ =    $ \times10^{-8 }\;F$ in  ----待选择----parallelseries 
$C_{min}$ =    $ \times10^{-9 }\;F$ in  ----待选择----parallelseries 

  A $3.00-\mu F$ and a $4.00-\mu F$ capacitor are connected in series, and this combination is connected in parallel with a $2.00-\mu F$ capacitor (see Fig. Below). What is the net capacitance? $C_{eq}$ =    $\mu F$

  If 26.0 V is applied /)pcf/-rxb4 ary *jy wacross the whole network of (Fig. Below), calculate the voltarcr* /x-)j4faw/yby pge across 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 x4hf7p .ih-ka22csshnmhq44tkpl6 + to 2900 kpsxi46 nf4+ph2ta lcmh2-47kh . sqhpF.
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 accik plkl180we l4dentally constructed using a $5.0-\mu F$ capacitor instead of the required $16-\mu F$ value. Without removing the $5.0-\mu F$ capacitor, what can a technician add to correct this circuit?    $\mu F$ conneected in  ----待选择----parallelseries 

Determine the equivalent capacitan2 ltb2x zs( kq36nhbe7g5;vm gce of the circuit shown in (Fig. Below).

  In (Fig. Below), if zlcq; ,z)g21olqd 3wz)u di*s$C_1=C_2=2C_3=22.6\mu F$, 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), suppose frq.e 977bvi lrl e-+n$C_1=C_2=2C_3=16.0\mu F$, 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 r -8f+.ban3u4on altn$V\,=\,78V$ 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 qivxy/q2 *1 xqshown in (Fig. Below). xqq21i *xqvy/
(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 singl euyg/t,/ u8jge 250-pF capacitor hooked across a battery. It is desired to store three times as much energy in a combination of two capacitors by adding a single capacitor to this one. y, utgj/g ue/8
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 unknta ;l ntj-m(f+ 0xbw*4ail2nw own capacitance, and as 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 plates, what is the unknown capacitan0amfnt-n2;a (lxbt+w *jw 4ilce?    pF

  Electrocardiographs are often connected as shown in (Fig. Below). ri6f+ ( p-76ncixk)eu/z-h hz gsth a)The leads are said toak (thgzh-6unx)pci+sfr6)i -z7e/h be capacitively coupled. A time constant of 3.0 s is typical and allows rapid changes in potential to be recorded accurately. If $C\,=\,3.0\mu F$, what value must R have? [Hint: consider each leg as a separate circuit.]    $ \times10^{6 }\;\Omega$

  In Fig. Below a (same as Fig. Below b), tk:ws *le.fi/o he 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 qq*ntg3s,b,: ln ,.+pmke qnk. Below a (same as Fig. Below b) has $R\,=\,6.7k\Omega$ and $C\,=\,3.0\,\mu F$. The capacitor is at voltage $V_0$ at $t=0$. when the switch is closed. How long does it take the capacitor to discharge to 1.0% of its initial voltage?    $ \times10^{ -2}\;s$
a
b

  Two resistors and two uncharged capacitors are arranged as shownbf.wkz05 g,k4xi2ndu in (Fig. Below). Then a potential difference of 24 V is applied across the combination as shown.42ku.gd5zk, wbf0x i n
(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 ,n8cze 0u 3z,erxp)7hf u :gziswd/j5250-V scale if the meter sensitivity cn)7eu0zesu,8:w,/jd3x5 zz h i pfrgis $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivity .+ tnbqt 6tbv *yo,v9n w5fvo2of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internalexoy 5:i5ptyy+n plt12n3 t*z 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 sensitivity-/ nmf+pxm fd7 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 10bt qu e7eiw99+sr0+e a 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 connz9z 8fq ;5bsg*(yt cctected 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 resist ;zmt :if5d3fnf1hf-i3;gnww w*)wc bf( vb(uance 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 vo5 d*tlnv svf(e0 n:7soltmeter of Example 19–15 have to be in error nld*(ofv7t5 s:0nv esby less than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. rrgr ( mt9w 2wb9vxnir4x) r6*ivb(,aBelow) 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 0.25-V potential difference between two poi;c:,p-w b nd2b*jwnmq 2od ip4l,2p vunts on the human body. The resistanci,2q42 p* wp2 dbwnv;jdomb c -npu:l,e 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, 1vw5fgz 6: 7lfg00 W, or 150 W, at 120 V. Such a bulb contains two filaments th6:lgvzff 5w7g at can be connected to the 120 V individually or in parallel.
(a) Describe how the connections to the two filaments are made to give each of the three wattages.
50 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
100 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
150 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
(b) What must be the resistance of each filament?
$R_{50W}$    $\Omega$
$R_{100W}$    $\Omega$

  Suppose you want to run some apparatus thf4pk(qdc fvv u6g)-;pat is 95 m from an electric outlet. Each of the wires connfgvf);-4d pp cu(q v6kecting 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 hospita(y iyjz e4r)ul8a*1dlls, particularly to patients who are connected to electrodes, such as an ECG. For example, suppose that the motor of a motorized bed shorts out to the bed frame, and the bed frame’s connection to a ground has broken (or was not there in the first place). If a nurse touches the bed and the patient at the same time, she becomes a conductor and a complete circuiraei 4uy1l jd8l( zy)*t 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 udl9a6y0 qzrc 6*qsh*45-V battery expend to charge a $0.40-\mu F$ and a $0.60-\mu F$ capacitor fully when they are placed
(a) in parallel,    $ \times10^{-3 }\;J$
(b) in series?    $ \times10^{-4 }\;J$
(c) How much charge flowed from the battery in each case?
$Q_a$    $\mu C$
$Q_b$ $\approx$    $\mu C$(Round to the nearest integer)

  A heart pacemaker iss/0(hly , t3.c;4geidpzr ty t designed 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 resist o1 b2;vaty( 9crxh *,fekfr1lance 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 measurements of 38q 02i 6ssub4i isrz6njmg+ eresistance. The unknown resistance to be mea+mqnsij 82zrg 64ies6bus0 i3 sured, $R_x$, 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 diam3 l5r3);fqk1gbcplsy eter is placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 13bflqp 5;)ylc1ks r3g and 2 have resistance of $38.0\Omega$ and $46.0\Omega$ respectively. Balance is achieved when $R_3$ is $3.48\Omega$ How long is the platinum wire?    m

What are the values of effective capacitance which can be obtained qyi 1fo .v,6*jc++5 oz0)yyctb llp ojby connecting four identical capacitors, eachczyl oyjo) 6,l0c 5 tvij.+fp1*+q oyb having a capacitance C?

  The variable capacitanceff ju r60(tt0r of an old radio tuner consists of four plates connected together placed alternately between four other plates, also connected together (Fig. Below). Each plat0r tr(tf u0j6fe is separated from its neighbor by 1.5 mm of air. One set of plates can move so that the area of overlap of each plate varies from $2.0cm^2$ to $9.5cm^2$
(a) Are these seven capacitors connected in series or in parallel?  ----待选择----parallelseries 
(b) Determine the range of capacitance values. from    pF to    pF

  A battery produces 40.8 V when 7.40 l)6dr,eah90;nci etvd / lh8gA is drawn from it and 47.3 V when 2.20 A is drawn. What are the emf eenh,rhc dt6)8dl/;v lg i0a9and 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 tj-rb,*wpp d4huwby; k2o q.(l he $4.0-k\Omega$ 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 cap 3y1ak-yx:lg uacitor 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;jg dd5u m*g1r 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, has an output of 350 mA at 0.80 V whoyamf q(, rf.8en exposed to full sunlight. A solar panel that delivers close to 1.0 A of current at an emf of 120fmf, .(8yqra o V to an external load is needed.
How many cells will you need to create the panel?    cells
How big a panel will you need, and how should you connect the cells to one another?    $m^2$
How can you optimize the output of your solar panel?    banks of    cells in series per bank, with the banks in  ----待选择----parallelseries  always have the panel ----待选择---- pointedturned  directly at the sun。

  A power supply has a fixed output voltage of 12.0ki)gyvz,q/ jmt 9w2b(j 1 *eev 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 inb(c) mz,8ndg0 0 v9bpb /wjilr (Fig. Below a) uses a neon-filled tube as in (Fig. Below b). This neon(b dmlcn )9zj 8rbbv, 0gp/i0w lamp has a threshold 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 th6rpf+ otgb. xkc3(j.fe $20-\Omega$ resistor in (Fig. Below) does not change whether the two switches $S_1$ and $S_2$ are both open or both closed. Use this clue to determine the value of the unknown resistance R.    $\Omega$

  In the circuit shown in (Fig. Below), thui+,dw j*ql,j1x qlkb:5 .svwe $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance of the circqi x;zl-gib 3 8/)bhdbuit 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. Below a) to0 sv.x*:l bs85pa*uid wap8ge measure a resistance R. If V is the voltmeter reading, and I is the ammeter si*5axpb.v 8l*s 0 pwueg:a d8reading, 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 operaeuxzs 36a.m,rk7qvz:ted by a 9.0-V battery. To light the bulb at its rated voltage and power, a resistor R is connezrqs.7z:,kv3a6u e x mcted in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$