Explain why birds can sit on power lines po+u*cuu (;gfmk:(mqydwkkf /u d: 3*safely, whereas leaning a metal ladder up against a power line to fetch a stuck kite is k*w :; f guuud3u/*(co:fyk +m(qdmkpextremely dangerous.

Discuss the advantages and disadvantages of Chrisd;yb(e+z*l gltmas tree lights connected in parallel versus those connected in series.+d(zl*geb l y;

If all you have is a 120-V line, would it be possible to light several;5f ,b7gwjz* b-ogaa5opngi: 6-V lampsg bngwfp 75,ao 5*bj-z;a:i og without burning them out? How?

Two lightbulbs of resistance)e +cv::: lv hc.iudp)q0qabk $R_1$ 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 /kk2eo9xggvsxm n /q* 3c7k v3m/ gaq;double outlets. Are these connected in series or parallel? How do you know? x9ck2g s;n/e*gvqvm3/37mqk xkao/g

With two identical lightbulbs and two identical batteries, hv.:kvz9f6 10 igzxb+oaza7iiow would you arrange the bulbs and batteries in a circuit to get the maximum possible total power o aga . +96z:f1zoivb xkz7ii0vut? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in series to a battery, does the batz0p z46ch jxj5tery have to supply more power or less power than when only one of the reshzx40cpj5 6j zistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the overall r+ -h,jk4zjk2 l4e6wle kfocd7/axcr/u;p 3 v tesistance of your room’s electric circuit change when you turn /wtlc 2zxoklc;j6f+4h7kk u /e4a-3v, rdjepon an additional 100-W bulb?

When applying Kirchhoff’s loop rule (s3rcznlpc1w8q .sq ibr 9l;j1+uch as in Fig. Below), does the sign (or direction) of a battery’s emf depend on tqj 19q3b +cnlr8.; cp1zliwrshe direction of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “increases,” “decreasehq9+4:uh l .8pzvclhviz9k m(s,” or “stays the same” to comph8 zp l9zvuvhl .4 :q9i+(chkmlete the following statements:
(a) If $R_7$ increases, the potential difference between A and E  ----待选择----stays in samedecreaseincrease . Assume no resistance in Ann meter and power supply.
(b) If $R_7$ increases, the potential difference between A and E  ----待选择----stays in samedecreaseincrease . Assume Ann meter and power supply have resistance.
(c) If $R_7$ increases, the voltage drop across $R_4$  ----待选择----stays in samedecreaseincrease .
(d) If $R_2$ decreases, the current through $R_1$  ----待选择----stays in samedecreaseincrease .
(e) If $R_2$ decreases, the current through $R_6$  ----待选择----stays in samedecreaseincrease .
(f) If $R_2$ decreases, the current through $R_3$  ----待选择----stays in samedecreaseincrease .
(g) If $R_5$ increases, the voltage drop across $R_2$  ----待选择----stays in samedecreaseincrease .
(h) If $R_5$ increases, the voltage drop across $R_4$  ----待选择----stays in samedecreaseincrease .
(i) If $R_2$,$R_5$, and $R_7$ increase, power supply (r = 0)  ----待选择----stays in samedecreaseincrease .

For what use are batteries connected in series? For wha*4tj8lshvb3 nxdzi2 j0 tsfs+, rf8 z)t use are they connected in parallel? Does it mai8s4 )x2flz, *st8nf3+0j vjhrdztb stter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever exceed its emf? Ex*)f+iu8ft w6wn q c*pxplain.

Explain in detail howgnojum)-, e0e o6ij y+ you could measure the internal resistance of a battery.

Compare and discuss the formulas for resistors and for capacitors when co3-rgp xwt*1eqh0 uj ;cnnected in series and inet;1 w p-j*xq0hugrc3 parallel.

Suppose that three identical capacitors are connected to a battery. Will 5-xoh*5uwhhenq .-r) -fs iumlsn: b5they store more energy if connnuw5)*h 5xf:5i l -oehhr-bumq -n.ssected in series or in parallel?

Why is it more dangerous to turnyc38x4;1 kpcs d) rjrr on an electric appliance when you are standing outside in bare feet than when you are inside wearing sck jy;dcp4x)r1rs3 r 8hoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) mp;;6 e48pqexf7 jusipd i5zp9jiuk1w *p+ 0clicrophone. 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 thee67 ksjiqfp; 9*dipu4up8zp je5w pi 01xc+; l same frequency as the sound wave is produced.

Design a circuit in which two different switches of the type shown iw8lwfw.8q:1ha8pr r7 rrpy.un (Fig. Below) can be used to opera1 8awr prr7.w :wpqrfy8.l uh8te the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from the battery until the capacitof -*wlph2vnw0 r is completely charged. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If not, where dopnh f0ww*-2vles the extra energy go?

What is the main difference between an analog voltmeter and an analog ammeterx5mke /.,pf+xa uo d+w?

What would happen if you mistakenly used an ammeter where you needed to use a v /yfo8h4r5ty5 xx uvcg5mw5h.oltmeter?5vg8fuy xwt.h5 /mchy4 rx55o

Explain why an ideal ammeter would have zero resistance and an bjnqw dn)*0f*cch)kl,ogp( , ideal voltmeter inf,0*gn)qp (h ,fojnlw c kcdb*)inite resistance.

A voltmeter connected across a r 14ibu4xqabd88 ljjc5h6yrf -esistor always reads less than the actual voltage across the resistor when the meter is not pr8 4lj 1aujx bhirqc8df-5b 64yesent. Explain.

A small battery-operated flashlight requires a single 1.5555xm0 *brbtxsu;qv/a g+svc-V battery. The bulb is barely glowing, bm v+a*xtsuxsrq5bgb;05 v5c/ut when you take the battery out and check it with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltagev-lpn*lbon uej b-1, 4 8eld8l for a battery with an internal resistance of $0.900\Omega$ and an emf of $8.50\,V$ when the battery is connected in series with
(a) an $81.0-\Omega$ resistor,    V
(b) an $810-\Omega$ resistor.    V

  Four $1.5-V$ cells are connected in series to a $12-\Omega$ lightbulb. If the resulting current is $0.45\,A$, what is the internal resistance of each cell, assuming they are identical and neglecting the wires?    $\Omega$

  What is the internal resistancep13yyot/ g-z pzfc 1vj:vpm+ / of a $12.0-V$ car battery whose terminal voltage drops to $8.4\,V$
when the starter draws $75\,A$?    $\Omega$
What is the resistance of the starter?    $\Omega$

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

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

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

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

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

  Suppose that you have a 4 mf3wu ax,,dece5f (rheg(r z)m5p 8z$680-\Omega$, 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 )t*a+xu9 coex$6.0-V$ 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 of g:foxbg1xf d1/s*rc ($12.0\,V$ 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 acr jyzkk7z 1dmhj ,: 336yf(wp ujhoz(7h9l rla)oss 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 connechd( +-m+r s)voitgfybs+1pz8 ted in parallel to a $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?
$V_R $ =    $\Omega$
firaction wasted =   

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

  A close inspection of an electric circuite75ku ev3i +td pjfz77 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. Beloqm w3y-ip;fi-w). Answer qualitatively: ip q-f3m;-wyi
(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 thum5x(x94 +ulgb ipx 5ie battery in (Fig. Below)? Each re4b (uiixl9up5x5 +gm xsistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown in (Fig. Be skk*or 8n;nt6low). Qualitatively, what happtk6r konn;s *8ens 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. Bec+xj) , 8:3( itndto9mv2 wl zssip9ud6aadu*low) and show that the sum of all the voltage changes around the dv (s+z, wa9:)tis2xan 98cjdmut6d3 pui *olcircuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal volta.rhu:byb8j4 ege of each battery in (Fig. Below). 18V battery =    V 12V battery =    V

  (a) What is the potential difference q8g+enlg )fr8;y/j1cn* a i5vhlq i6kbetween points a and d in (Fig. Below a) (same circuit as Fig. Belohyr 8)8c5/ki6*li+q1nggalj v; qn fe w 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 (Fgq j7 a9n2pwc)v7 ys xhf9)ig2ig. Below), find the potential difference between poinqai pg2 w )njsx9)v9yg2ch77f ts a and b. Each resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and diref,2p, *5 vtpsvnapcg( v3y 74i:ipjxections 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 internal resi4v+yfdzjr)y1mit 8ocs :ty4 yj2 * :hsstance $r\,=\,1.2\Omega$.
$I_1$ $\approx$    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 resistod 9gmr*3))dcmj5 hjb fr shown in (Fig. Below). The batteries have emfs of cm)brjfmdj 3h) *dg95 $E_1\,=\,9.0V$ 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 intern7or,,ox df iti-ng k:2al 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- e+zdhjw)tec1rb3l - ve1p9x5cr /fl each resistor of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curr n 3rf5fy5byvz2fsv v o;f-/h*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 6mls;qxw90j -a5 c0:vmt qhgm$I_1$ 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 asq b3 h)75ylkxh shown in (Fig. Below). If eh qk5x3ly7hb)ach 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 capacitkt6sddwa:0s cw86h5 jors, 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 across the whole netwog64; eursm 8igrk of (Fig. Below), calculate the voltage across eag iu8em4r6 ;sgch capacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of+vo)bq 3 k-(h;ci4ejbl3tb au a circuit is to be reduced from 4800 pF to 2900 pF. v)l(3hkb bct i; +u jeq34ao-b
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 constrj zmx,e9pd;+qfh k8t crvhxv78d:x (;ucted 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 equiva osv0 nyrxfi9fo478f*lent capacitance of the circuit shown in (Fig. Below).

  In (Fig. Below), if j1mnu 1hop:g9m-0qw u$C_1=C_2=2C_3=22.6\mu F$, 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), supp1djsrmno;-th2. , e ldose $C_1=C_2=2C_3=16.0\mu F$, 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), letk-wx)dfg/d 3di b3o-v d7o(ovpzb8; r $V\,=\,78V$ 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 (Fig. Bq:+zp ytj4 ln:elow).pjn :tq 4l+z:y
(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 batter9 qcajz z32g,.7gm hiry. It is desirearzc.qgm 7zi j2,hg39 d to store three times as much energy in a combination of two capacitors by adding a single capacitor to this one.
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is connected in series s)uua5ece a 07(h f0evwith an unknown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 18 u e7s0hcua)v(e5fea05-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often c3c+hhrsn e1(o ivliw w8mn a jl;0n+71onnected 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 chavnm( l+n 7i3ea 0+l;hww81h 1 osncijrnges 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 k6w.u)l4 jk1 xolqb7was Fig. 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*s-f y *k0ecp6nzgx 2a 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 twtt/hhf2 wr 6d4o uncharged capacitors are arranged as shown in (Fig. Below). Then a potential difference of 24 V is ap2hr f6hwt4t d/plied across the combination as shown.
(a) What is the potential at point a with switch S open? (Let $V=0$ at the negative terminal of the source.)    V
(b) What is the potential at point b with the switch open?    V
(c) When the switch is closed, what is the final potential of point b?    V
(d) How much charge flows through the switch S after it is closed?    $\mu F$

  What is the resistance of a voltmeter on the 250-V scale ifwa ju366v nhlqd5wm)* the meter sensitivityw)nj vl5uhd*w6a3mq6 is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivity ofywy/ a(wnbv16 $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internanul 8anky ,, w)t j*dncaf/5roa(rl 4/l 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 sewuo83d791 r7jo axua17kpdqz s ;l+xknsitivity 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 full scale. It con*+ncx r3 n4+bel zyh8usists 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 resio(n9t6 6hd;oepk;d mystance is connected to a $R_1$=$38-k\Omega$ and a $R_2$=$27-k\Omega$ resistor in series. What reading will a voltmeter, of internal resistance $95k\Omega$ give when used to measure the voltage across each resistor? What is the percent inaccuracy due to meter resistance for each case?
$V_1$$\approx$    V (retain one decimal places) % error    % too  ----待选择----uplow 
$V_2$$\approx$    V (Round to the nearest integer) % error    % too  ----待选择----uplow 

  An ammeter whose internalag7 *u+-adv qpw ww68w+8vtul 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 resistance should the voltmeter of Examp0 7lvu kfd. m..dg.)f-p;gymkzy th2 b,-wcenle 19–15 have to be in error by gh f-)d dmy0gz;ek.vfbn-cl7ypw ..2mu.k,tless than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Belowu/ 1bh:papf i5) 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 k;p1h xk2wp)l difference between two points l xwp)h pk1k;2on the human body. The resistance is about $2000\Omega$, and you only have a 9.0-V battery. How can you connect up one or more resistors to produce the desired voltage?    k$\Omega$

  A three-way lightbulb can produce 50 n9pl l l0ta(2d+)zfl xW, 100 W, or 150 W, at 120 V. Such a bulb contains two pa lft+z0(9)lxl2ndl filaments that 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 runz dz h4hpwhk8 ou/6/0ip rw8h9 some apparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 1d 6z4p/wh8i o0wu/ ph hzkhr8920-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 hazardiz6n 6htfu2h + in hospitals, 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 tzt6fh6+2 nihu he 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 bad0-0v s;rue,upuk, vhttery 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 azn/ycbq-51e/gal33q 4z) onbcs 1cvxt 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 resistf/ d-wpn,xpm 9ance 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 4j3r46-/oc-kzll+kdvecrcm circuit” used to make measurements of resistance. The unknown resistance to be measured4k cd-+4rlck6 v- zrel/jco 3m, $R_x$, 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 placxf-hgci2t .:qd p2fa o 3 qm4idva3u-,ed as the unknown resistance in a Wda v,o f. afmu34i dx:-cqgp22-thiq 3heatstone 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 can be xgse6jmj0(9 rx.bq5bp 9 rel 6obtained by connecting four identi 6x0e6b.sjmg 9px b5j re9l(rqcal capacitors, each having a capacitance C?

  The variable capacitan2) jtz+)f;anjp-nmo hce of an old radio tuner consists of four plates connected together placed alternately between four other plates, also connected together (Fig. Below). Each plate is separated from its neighbor by 1.5 mm of air. One set2f+)zn-)jm; tpa nh oj 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 24) 3mr-k tpj4nd,jbkgo+hr l7.40 A is drawn from it and 47.3 V when 2.20 A is drawn. What are tnb+ to-kkm2 rh pjr43ldjg,)4he 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 t7)lvc + bfm-0 rrdg)3ild8hb5c lhei0g( hqv9he $4.0-k\Omega$ 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 capk.uowku(5bd6q e4dx,6bvr s8acitor has capacitance $C_0$. If two identically sized dielectric slabs of dielectric constants $K_1$ and $K_2$ are inserted as shown in Fig. 19–64, what is the new capacitance? [Hint: treat this as two capacitors in combination.]

  For the circuit shown in(Fig. Below), dentww8 a d 1ije)fg)u9gcoa **8termine
(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 oii ..9p c93hnpb .kah3fg2 sszik d9q1utput of 350 mA at 0.80 V when exposed to full sunlight. A solar panel that delivers close to 1.0 A of current at an emf of 120 V to an exd9p9 2.9pa k3ik.sfzs 1qch3igi n .bhternal 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 voa 6-edx+j ymn:ltage of 12.0 V, but you need $V_T\,=\,3.0V$ for an experiment.
(a) Using the voltage divider shown in (Fig. Below), what should $R_2$ be if $R_1$ is $10.0\Omega$? $\approx$    $\Omega$(retain one decimal places)
(b) What will the terminal voltage $V_T$ be if you connect a load to the 3.0-V terminal, assuming the load has a resistance of $7.0\Omega$? $\approx$    V(retain one decimal places)

  The circuit shown in (Fig. Below a) uses a neon-filled tube otihev;gu :w; + kjrs962svh8as in (Fig. Below b). This neon lamp has a th j+2tok;grsi8s9vh6w : u; vehreshold 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 the0tris3xu-mx-4 bw,b u wyd7f;e n *f.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. -ogg m.n+ty3 ue )64mfw )zxloBelow), 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 ofab7 4vm 0bsqi0 the circuit shown in (Fig. Below)? $R_{eq}$ $\approx$    $\Omega$(retain one decimal places)
(b) What is the current in the $18-\Omega$ resistor?    A
(c) What is the current in the $12-\Omega$ resistor?    A
(d) What is the power dissipation in the $4.5-\Omega$ resistor?   W

(a) A voltmeter and an ammeter can be conn0kfbmmcxeg 9+-::mb -infm)k ected as shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I m 9xmncme-0 f)kmfk b:b+i: g-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.trmm z3*r,k66vhcs6c 0 V is operated by a 9.0-V battery. To light the bulb at its rated voltage and powersrc6 3r kmhvtc,z66m* , a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$