Explain why birds can sit on power lines safely, whereas leaning a metal s67lts *lx viyl+l6d 8gn d9+ka1,h dcladder up against a power line to fetch a vl+6dx,s*6g 1dsl+lyt9n78ka lhcid stuck kite is extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree:mut2ycxei5 z *g *ulhkf iveg)6yh--0:uu*j lights connected in parallel vers *2- tu gxl-ce6iu5*jkv izh 0muu*:ygh)fe:yus those connected in series.

If all you have is a 120-V line, would it bdr1rx7 d9wjn 0e possible to light several 6-V lamps without burning them on0 d7xw1rr dj9ut? How?

Two lightbulbs of resi;j5sz e1 w1mtwnent4o1j (q.lstance $R_1$ 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 uyqz, t2 axe1i 4koax4c*d:o1/5s mcdoutlets. Are these connected in series or parallel? How/q:mc,4a 1yt*do4cdk12 uxa xio sze5 do you know?

With two identical lightbulbs and two identical batterie:oi2 3 r:il*k6ruatrqs, how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume theo* 63 rialur:q2:tir k batteries have negligible internal resistance.)

If two identical resistors efs51d x3bdm -svbi/0u .-e6gcpa7be are connected in series to a battery, does the battery have to supply more power or less power than when only one of the resistors is connec .iv1e- pe s0g cxb 7a3-bmes65db/fudted? Explain.

You have a single 60-W bulb on in your room. How does t mf uef6)m+xv/ca*adyx+ -j 7jhe overall resistance of your room’s electric circuit change when you turn on an additional 100a j vm *6++7yj)c/d-mfxaex fu-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below), does the sign b-r 2qr yj6usg,ko4r3(or direction) of a batterybgj-2 os4yurr3kq6 r ,’s emf depend on the direction of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 1 a/8zy,w) ivoj9–36, use the words “increases,” “decreases,” or “stays the same8 w/yzvjao) i,” 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 batterdp)m-j)yqwtfh4q+ /5yy w3f ( )kl zugies connected in series? For what use are they connected in parallel? Does it matter if the batteries are ne hw/)t+3(45jydqq-z kyflgpmyw)f u) arly identical or not in either case?

Can the terminal voltage oscbp:l zql-o-u 9v*ck- 7aq0rf1(noif a battery ever exceed its emf? Explain.

Explain in detail how you could mea2 zzmlaf/)-d(m fx,ossure the internal resistance of a battery.

Compare and discuss the formulas for resistors and for capacitor1 +3bt8hgbddxci8 ls 8f yzz:di0.v0ls when connected i8 l:.t if3i 8 +z0hdbzxsd1l8cgv y0bdn series and in parallel.

Suppose that three identical capacitk9 )tdi7 w0uuiors are connected to a battery. Will they store more energy if connected in series or inui0)i9 utw7dk parallel?

Why is it more dangerous to turn on an electric appliance when you are stanotjcd+t(6m x bu5o0tq f, eh78ding outside in bare +( bmto0fhejo u dq56t t7cx8,feet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) micr hspclg, wfu2h(8b 4 c4*w0cvrophone. The changing air pressure in a sound wave causes one plate of the capacitor C to moh84(c lw*4 s0gfvhbpw rc, 2ucve back and forth. Explain how a current of the same frequency as the sound wave is produced.

Design a circuit in which tr9 lo 9mohma/4wo different switches of the type shown in (Fig. Below) can be used to operate the same lightbulb from opposite sides oa49 o mm/h9orlf a room.

In an RC circuit, current flows from 3tl *ow5ukb 0athe battery until the capacitor is completely charged. Is the total energy supplia0o u3 lktw*5bed by 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 analog ammeter?r3 e3u 9lsc5ru

What would happen if you mistakenly used an ammeter z,+eg 0xe+i 8yfwu:jvrg4( udwhere you needed to use a voltfz0udgv4y(u:+g+rjwe8x , i e meter?

Explain why an ideal ammeter would have zero resistance and an ideal voltmeter mshxr 6)r itufw,.-p( infinite rs-ih.p,()t fwumr rx 6esistance.

A voltmeter connected across a resistor always reads less than themoj qgd:ren0 /tay/z.7f,s 7sw;oo9 x actual voltage across the resistor when the meter is not pro/:qg dj7orse s;fwy7/,n0 .9atmxozesent. Explain.

A small battery-operated flashlight requires a single 1.5-V battery. The bulb gl.( x,;qjnnwis barely glowing, but when you take the battery out and check it with a voltmeter, it registerj.,x ;wnlgn q(s 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an internal f0s:b6e5 snj6dy . i8adcra z3resistance 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 resistance f1( 5y eu5quknof 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 ugp auomjs ckex42/p814. x6ya $680-\Omega$, 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 cxhqklo) rhyt,e202xp/b8 pu +wn. , ta $6.0-V$ 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 ok.k(:gwsp njnj.o1 v *h0rd p-f $12.0\,V$ 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 acrwx /b:3jsu+sxoss 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 pjakonj8b/h-fd g4/9*7 2lxaark 7w raarallel to a $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?$V_R $    $\Omega$   

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

  A close inspection of an el et9 bzd s,coa5.:z4xm+ u,fbgectric 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 resistors shown in (Fig. Below). (4yhaz kl7s, 7du0n.crz5uak Answer qualitatively: ls u(k0r .u5ydz4akazhn7,7c
(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 batb+o(cr7ms gfpq3hq 5: 7plb4xtery in (Fig. Below)? Each resistance has b x+pcgl3 7 fospmq( 7hq4r5b:$R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to fs x7 ih,mqsqs-y9r99 a battery as shown in (Fig. Below). Qualitatively, what happens s xy9f s-mrq97hs qi9,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 t1hdl c mx3..z0rlo34apg ,rvwd )wce /hat the sum of all the voltage cvolc .rdcg3 )mhedw1/w3. xzr,p04al hanges around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each battery inp,p2 ioy0u0r:fz, 0w6lbltj b (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential difference between points a and d in (Fi9e2z6 /fh8k,mb(zouws ad f.jg. Below a) (s.s6bwfak(2j/ ufd8oz ,zh 9 emame 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. Below), find the potential diffei hqz96-fi 0+ofr8cawrence between poinfaq+w fi8 c96 oirz0h-ts a and b. Each resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and dir3 nx8 hq9uphg(* k:kefections 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 eachukz140ybv(u6 im1eiv5izi ;w battery has an internal resistance $r\,=\,1.2\Omega$.
$I_1$ $\approx$    A  ----待选择----leftright (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftright  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftright  (retain two decimal places)

  Determine the magnitudes and directions of the currents in each resisto ls2(ci7.2szhrn b:bf3yh1ct huhi49 r shown in (Fig.cb:rt 2b4sh7hf .i u i9c( h1ysl2h3nz Below). 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 v-ag tq/5+fi0gn9 wt iresistance $r\,=\,1.0\Omega$.
$I_1$ $\approx$    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 re9vvcdu+w2g okeqy *c9b8 8z7xk7fv8 d sistor of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currentoclqv,j30 rk, s(qqx )s $I_1$,$I_2$, 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 currentqwyc70 vqv /n6t* 7dwg $I_1$ 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 asyz59o2(c rn cj2zu8og shown c9 (z28gzn5croyj2 ouin (Fig. Below). If each internal resistance is $r\,=\,0.100\Omega$ and $R\,=\,4.00\Omega$, what is the voltage across the resistor R? $V_R$ $\approx$    V (retain two decimal places)

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

  You have three capacitors, of capacita1 4n fe08tg3lql5ejv cnce 3200 pF, 7500 pF, and $0.0100\mu F$ . What maximum and minimum capacitance can you form from these? How do you make the connection in each case?
$C_{max}$ =    $ \times10^{-8 }\;F$ in  ----待选择----parallelseries 
$C_{min}$ =    $ \times10^{-9 }\;F$ in  ----待选择----parallelseries 

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

  If 26.0 V is applied across the whole network of (Fig. Below),2p x3dybr)evrq +v *l. calculate the voltage across each e v .2vr+xbdl)3q p*yrcapacitor.
$V_{2.00}$    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 2900 rxr3-xe*+1) wqok.istp-dve7v / r k qpF./ *k-i-kv d vorr q3)+1wp exxrqe7st.
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 consaahtj0orrw.u:i - j+ *tructed 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 capacin t xly-cn.djl+ ih+6,tance of the circuit shown in (Fig. Below).

  In (Fig. Below), if +k v-yrg roy60$C_1=C_2=2C_3=22.6\mu F$, 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 tn :sck 6e3e.84kq 8jzpjs-e3kwap,fse $C_1=C_2=2C_3=16.0\mu F$, 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 dl7nb -x qiz.)$V\,=\,78V$ 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 cf *poxhg o936xonnected as shown in (Fig. Below).f6 og*xhxp93 o
(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. p 2rn ly3q04e4a.nov5zyij*clul 7l1 It is desired tyjy3i4o1 pn75.*n la2v ezcur0l l4qlo store three times as much energy in a combination of two capacitors by adding a single capacitor to this one.
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is connected in seriesco4g7/8 mexl exz7zv- with an unknown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If8/ e7m4clgex7zvx - oz the 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often connected as shown in (Fig. Below). The87dav1ffak re gtt 2g/y (t)+w leads are said to be capacitively coupled. A time constant of 3.0 s is typical and allows rapid chaa(2gtayed87fwt) f1/ vtk r+gnges in potential to be recorded accurately. If $C\,=\,3.0\mu F$, what value must R have? [Hint: consider each leg as a separate circuit.]    $ \times10^{6 }\;\Omega$

  In Fig. Below a (same as Fig. Below b), the tn ry 4adx n y;:3f0s,l*tst;wpotal 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.9pz12t *y59gz shk exk*j/z5sxdb+ jt 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 capacito mv;y b8,,i;mt+l gd ae1(dn eeomq)b2rs are arranged as shown in (Fig. Below). Then a potential difference of 24 V is applied across the combination as shoe ;+2e(gdea;,mnobi b,vmlyt1 ) qd8mwn.
(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 scj12. fhls.zz iale if the meter sensitivity is h2z j.fisl.z1$30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivit8d. f0,vqgpnn,s 48ksc zfnf3y of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal1bt(dtgj2 dn(6b0ph7 b fs+pj 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 sensitivit8 / u)i2uzluhqy 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. tfj reteiam4p(mh ;u/z.e( , 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 c)p;9qf)j fz) h,kd)5l gh 6jj kty0ckaonnected 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 intern xc(vkicik6t .m*ax9 q6g8b7 ral 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 resistalhhu d0jp0 .g:nce should the voltmeter of Example 19–15 have to be in error by less00l jhd hupg:. than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig.xi6 tx8ifb/c - Below) is $35\Omega$, the high-resistance voltmeter reads 9.7 V. When R is replaced by a $9.0-k\Omega$ resistor, the voltmeter reading drops to 8.1 V. What are the emf and internal resistance of the battery?
r $\approx$    $\Omega$(retain one decimal places)
$\varepsilon$ $\approx$   V(retain one decimal places)

  Suppose that you wish to apply a 0.25-V potential difference between two point hlxz3xuwj hc*+.b-.e s on the human body. The res xlu ec+* hhxbwj.3z-.istance 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 W5+wx mawh q/vs /./ tzyg8js4t, 100 W, or 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually or in paralq/ wxsgatmwj+s4.y 8 v 5//tzhlel.
(a) Describe how the connections to the two filaments are made to give each of the three wattages.
50 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
100 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
150 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
(b) What must be the resistance of each filament?
$R_{50W}$    $\Omega$
$R_{100W}$    $\Omega$

  Suppose you want to run some apparatus that is 95 mt ,x/z xq-r m96f5skaf from an electric outlet. Each of the wires connecting your apparatus to the 120q59xra6fx/, z f tksm--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 hmzc02nksqz t g jol)4-r tk u./z+:jp,ospitals, 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 circuit can be made through the patient to ground throut)uztlzmj- r:/q g 2 ncpjs.k4k +0zo,gh 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 enep1zp(joed r rb -7kr8v: tw(7e0 dl8xpend 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 beat-ckomkqxx)p*34kl 9zw6/ ,itq qkg4a s/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 resista3a;u( jvntb af2z a;u8nce 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 mak2k.d 4s+y0b5 2rdrnw-li xbb-a to)nfe measurements of resistance. The unknown resistance to be measun. bfxwtb dor4ry20 5a n-s-ibd2k+l)red, $R_x$, 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 unkno7jyqb-cixbol +- 3w/v wn resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 havy 3 +-7-owlixqj bv/bce 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 effe 1z2e04vm/zikm,obn:nvy y8octive capacitance which can be obtained by connecting four identical capacitors, each having a capacitancem 01v82kno vn b/4mz,yio:yez C?

  The variable capacitance of an old radio tuner consistp ;ayrw.um* bunkt+ - :84yzkrs of four plates connected together placed alternately between four other plates, also connected together (Fig. Below). Each r-.y4 mw tpun+8abuy z:r; *kkplate 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 4tj7 8r,3sgd ylnwh- d 6,gsi;o0.8 V when 7.40 A is drawn from it and 47.3 V when 2.20 A is,d l67js-nw r8sogg;dity,3h drawn. What are the emf and 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 thev8ub* lhfw0h 9 $4.0-k\Omega$ 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 c(7klgw*hq k2 u awjj;8apacitor 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 shownnnhzxf y3j,t 8n: *vi/ 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 0.3b b cu*o)6ap rrb7ly(5l4 k 5zz3jppn80 V when exposed to full sunlight. A solar panel that delivers close to 1.0 A of current a u a3bppc5)5bpjl b k6(7ry4onr3zzl*t an emf of 120 V to an external load is needed.
How many cells will you need to create the panel?    cells
How big a panel will you need, and how should you connect the cells to one another?    $m^2$
How can you optimize the output of your solar panel?    banks of    cells in series per bank, with the banks in  ----待选择----parallelseries  always have the panel ----待选择---- pointedturned  directly at the sun。

  A power supply has a fixed output voltage of 12.0 V, but you neea 2aut07 j9 zd,p7pgbwsk+r d)d $V_T\,=\,3.0V$ for an experiment.
(a) Using the voltage divider shown in (Fig. Below), what should $R_2$ be if $R_1$ is $10.0\Omega$? $\approx$    $\Omega$(retain one decimal places)
(b) What will the terminal voltage $V_T$ be if you connect a load to the 3.0-V terminal, assuming the load has a resistance of $7.0\Omega$? $\approx$    V(retain one decimal places)

  The circuit shown in (Fig. Below a) uses a neon-filled tube as in-nwlh iznh 38ko9f j:, (Fig. Below b). This neon la:nz 9jif-, lhoh3nw k8mp 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 thna6ky ea):kiyk* l:0u e $20-\Omega$ 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. Belowon4hp5s*6x1ug,vib 2 cz (m4xqhyvf .), the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance of the circuit shown in (F-th;*qv xwvrbdeb ;3*ig. 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 (kgs (kikk-r91 Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeter reading, the value of R will ik19kr-ks( gknot 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 atl1y/ n 0.(4pktjlxqok 2.5 W and 3.0 V is operated by a 9.0-V battery. To light the bulb at it xonqpjtl/4l 0ky(. k1s rated voltage and power, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$