Explain why birds can sit on power lines safely, whereas leaning a metkp -zh0.9px .q k 7zbdi2pn;fqal ladder up agaxq -kq i9f;.d7.bzknpp2 0h zpinst a power line to fetch a stuck kite is extremely dangerous.

Discuss the advantages and disadvantages of Christu rank )b8n7agy1to9+ (7xv/; rzbbjwmas tree lights connected in paralletnrbg+n uvy1x w9jz(/;a)7ra7b8bok l versus those connected in series.

If all you have is a 120-V line, would 6i n lm;ooi7m q8hwp10it be possible to light several 6-V lamps7imp 6ioo 0 l8;nmq1wh without burning them out? How?

Two lightbulbs of resis jj.ktz b2v-c/ pw37z9i+dyt+ooz rd;tance $R_1$ and $R_2(R_2>R_1)$ are connected in series. Which is brighter? What if they are connected in parallel? Explain.

Household outlets are often double outlets. Are these connected in series or pabav- 96w3447iz4 xzou bjzj hjrallel? Hbvizo4w b h4j7ja6z4-3u9 zx jow do you know?

With two identical lightbulbs and two identical battcdav pa xl0lo134r 7(deries, how would you arrange the bulbs and batteries in a circuit to get the maximum possi7axld41l0vp 3dc(a r oble total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in series to a;;u dfemtvt c d +lz,,+t,t6wg acq1k- battery, does the battery have to supply mor wltdcd++ k6 -;vtugceam,tz;1q ,,fte power or less power than when only one of the resistors is connected? Explain.

You have a single 60-W bulb o7 iv.y- d 5k)r iq);dabeayo3un in your room. How does the overall resistance of your room’s electric circuit change whk)dr 7 y.yuev3ad-i);obqia5 en you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule /hu bj/;l(n wu(such as in Fig. Below), does the sign (or direction) of a batu;h(//jwlu b ntery’s emf depend on the direction of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “incp,4m*mfu4oat-m i8 w7 f xjx9oreases,” “decreases,” or “stays the same” to complete thef,ujf9xao8o t-i4wm m xm*7 4p 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?s0l94 i mr79q( aus .1 htphagk/e)ag/c- trgx For what use are they connected in parall1cp . x7 q(hhk sgag9)9gt/ltr0amu4rsi/e-ael? Does it matter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a de8k6krt(pv1i: 8 zvrbattery ever exceed its emf? Explain.

Explain in detail how youv wsmryh q;/n-3b/hu, could measure the internal resistance of a battery.

Compare and discuss the formulas for resistors and for capacitors when connev xh0vcjw9*b*cted in series and in parallex*vh*cw0j vb9l.

Suppose that three identical capacitors are connected to a battery. Will they kazn 8+wcm4 e q,e z1s8vcj12ustore more energy if connected in serisq1j,nm8 kv+ u482za1zcwece es or in parallel?

Why is it more dangerous to turn on an electric appliance when you ar3plwoaxo z6,),pkix 7 e standing outsid plp),xzoa3kowi6,x 7e in bare feet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (oogr*-ky(1 zw)z*.,l6le8 pwb lyi rixr condenser) microphone. The changing air pressure in a sound wave causes on18olizxlgy) e(* li w rwz*by-p,.r6ke 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+i6 ggpuw o(rz ig:h -n9y:dt8 of the type shown in (Fig. Below) can be used to operate the same lightbulb from opposite-tinggwphyr dz6 u:go( 9i+8 : sides of a room.

In an RC circuit, current flows from the battery until the cap)lr xbrkse(4o cmr/g5 nnh 2qz-y)1/r acitor is completely chas cx)b 4rr2oryk )-q(e //m5nzgn lr1hrged. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If not, where does the extra energy go?

What is the main differ,gie( fj 2txk,ence between an analog voltmeter and an analog ammeter?

What would happen if you mistakenley*w0,-vag): qpe.ac 12f5q wbytnwx y used an ammeter where you needed to use a voltmet,xybynf1 2gte*5 a -pqw:cq.a w)v0weer?

Explain why an ideal ammeter would have zero resistance ajt0 bit jb66k*nd an ideal voltmeter infinite resi6i0 t *tjk6jbbstance.

A voltmeter connected across a resistor always reads les40wu 8 fve (a8frazw:xs than the actual voltage across the resistor when the meter ifwxer:a4 0(zwvu8 f a8s not present. Explain.

A small battery-operated flashlight rex6ubv w g-(y:)pq3oq )rg+mj tquires a single 1.5-V battery. The bulb is barely glowing, but when you take the battery out and check it with a voltmeter, it registers 1.5 V. How would you explavgo-)u ywmq+ j( b3x6) t:rqpgin this?

  Calculate the terminal voltage for a battery with an interna d4cbcc) 9/hiv.* vxafl 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 resistance of 7cxz:ifk(-/vc /t s7 zecsq s,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 e-yc0 yvm9*pu $680-\Omega$, 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 havea*r,cogz;p 2 s a $6.0-V$ battery and you wish to apply a voltage of only $4.0\,V$. Given an unlimited supply of $1.0-\Omega$ resistors, how could you connect them so as to make a “voltage divider” that produces a $4.0-V$ output for a $6.0-V$ input?

  Three $240-\Omega$ resistors can be connected together in four different ways, making combinations of series and/or parallel circuits. What are these four ways, and what is the net resistance in each case?
The resistors can all be connected in series   $\Omega$
The resistors can all be connected in parallel.   $\Omega$
Two resistors in series can be placed in parallel with the third.   $\Omega$
Two resistors in parallel can be placed in series with the third.    $\Omega$

  A battery with an emfmcys,.sq e;1qfi 0w j/ of $12.0\,V$ 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 e(8nt oskbrs))upw .0 series across a $110-V$ line.
(a) What is the voltage across each bulb? V$\approx$    V(Round to the nearest integer)
(b) If the current is $0.50\,A$, what is the resistance of each bulb, and what is the power dissipated in each?
R $\approx$    $\Omega$(Round to the nearest integer)
P $\approx$    W(retain one decimal places)

  Eight lights are connected in parallel tokvys/6 0 umv28pz zo1u 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 euff+ dv lrj(tfc *37f +b,+ytolectric 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). Answer quanng 41l2 (tfee2eivew gm5 t.3litatively: 1 e(2 eg5ineg tt.l nw32evmf4
(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 convhb 7n t3w1o(pnected to the battery in (Fig. Below)? Ebtnhp7v(ow31 ach resistance 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. p;(mt9p jm z8mhey(a). Qualitatively, what happens 9(e8 tj(.zmp ympm ;ahto
(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. oa1hrwd q-(a) Below) and show that the sum of all the voltage changes around the cir wrdq(a-1 a)ohcuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal voltage of each battery in (Fig. Below). 18V battery =7i n.2xv f/trg    V 12V battery =    V

  (a) What is the potential diffekuelwqbp6914-bp r fzquc-*. jdj j*:rence between points a and d in (Fig. Below a) (same cirljw9z-*j .qbp:ueb-kju p*6 14 cf dqrcuit 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 differenvdqhg-xzn5 cuod: j nt34; 63pce between points a:p53 o qn;chdxu6dt gz3jn-v4 and b. Each resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the curre)5, eejq nigl.qq gk:7nts 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 at2 yoph dk h5+*k0(h- iazry4vn 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 resisyo:gtn8m 5 /2gp3zv-z jmla-etor shown in (Fig. Below). zvme 38 gz/-yj-mgla52p:ont 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, assumijp; jqord+0z1y/v 5 tkng 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 currenesp nn5y)xa+ed0c,g 3ts in each resistor of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curre;yoog;2+ bfiw nts $I_1$,$I_2$, 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 *8 pcjvfl 6v1.ddk,z5uw m*yt $I_1$ 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 embt+/z h/ads 2pfs of 2.00 V and 3.00 V, are connected as shown in (Fig. Below). If each internal resistab ptza+/hs 2/dnce 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, 4gip )bz7fann1q j hr2is7rxayz6596of 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 network ofvhm) /f0lythhvp)sfj 0( v(k 0 (Fig. Below), calculate the voltage across each cvl)v )h (j0vstmhyfk(hf/0p0 apacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion ofo6w,s j .j)kxbz idzn-52n2*x cvuaws*o : h6d a circuit is to be reduced from 4800 pF to 2900 pF. 5x sjoiobw6:.jsn ) vwkhxz2ac z*-2un,6dd*
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 coxepv ye;r*):ut,tvd ty t:+o o uy2+2tnstructed 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 capaskf 1h*w02 ag osbs7hej 10zrw9pxc,1citance of the circuit shown in (Fig. Below).

  In (Fig. Below), if jqp.n gypz x8-8 */q sm1asas($C_1=C_2=2C_3=22.6\mu F$, 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:h,i zyvu3 1 oe(po5dgse $C_1=C_2=2C_3=16.0\mu F$, 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), lete/z :lt7of8je if7ia*r7zh0tm a/ t3q $V\,=\,78V$ 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 conn7;k adn 083 hczqtucw6ected as shown in (Fig. Below).c;q 6awh038z 7ndctku
(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 capacit o tyk+xc 5g6;uwow *e;yq-c+ior hooked across a battery. It is desired to store three times as much eoo+e+ *6yy i;5xuwwt ;cc-qgknergy 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 insk1 1g p h2ra7i mg0n15+mlrph series with an unknown capacitance, and as a series combination trpk ga7 mm12h lisrgp+h1150n hey 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 capacitance?    pF

  Electrocardiographs are often c1g qwl3xy-b 3/8r kvajonnected as shown in (Fig. Below). The leads are said to be capacitively coupled. A time constant of 3.0 s is typic1 ab/kg3lyr-jq3xwv8 al 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), the total resistance isph6j/lf pf os8xwd,-1mc (5ru $15.0k\Omega$, and the battery’s emf is 24.0 V. If the time constant is measured to be $35.0\mu s$, calculate
(a) the total capacitance of the circuit    $ \times10^{-9 }\;F$
(b) the time it takes for the voltage across the resistor to reach 16.0 V after the switch is closed.    $ \times10^{-5 }\;s$

a
b

  The RC circuit of Fig. Below a (same as Fi-z(idux )qv; fg. 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 c*gq 6ftt9 t;seapacitors are arranged as shown in (Fig. Below). Then a potential6f;ttst egq*9 difference of 24 V is applied 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 umfsl129*bhc a voltmeter on the 250-V scale if the meter sensitivity 9lc2sumhf 1*bis $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivile(m wjzsb3azv(y4 kt+ ytq:0u )5+r uty of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an q pcf9c jxo:yf/d+,8d internal 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 sensitiv4g**l- ljua i rw*(vgdity 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 consists of hg6zv64vmjd f, *swj2a $0.20-\Omega$ 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 neg)tniy:6uq2:2,jr) t ob iijckligible internal resistance 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 internal resistance evo a )4rgpr2:pvouu/2ta08 uis $63\Omega$ 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 shofbhzkljkzytar57l,-5* ej: a(59lh ould the voltmeter of Example 19–15 have to be in error by lzt :5f59 lh*ll,-kyjhz75rbe ( ajoakess than 3%? $\approx$    k$\Omega$

  When the resistor R in (* jly4:tuw qxf*)n:ir9fyi4 eFig. 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 apprlv ona tikt6h+m n.1*1 m87) 1fnejpvly a 0.25-V potential difference between two points 7hn.of)lnmj k1 1m1t*ev pitn av8+r6on 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 ha chmc3-7h6-,gn bt er0 e6mxW, 100 W, or 150 W, at 120 V. Such a bulb contains two filamencx7 emrmba-hgec66-n,t0 h3h ts 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 run some apparatus that is 95 m from an wvza/2 xf 17,vk)emv *llv:xeelectric outlet. Each of the wires connecting your apparatus to the 12ve / *vw )2az,lkx1x 7flmv:ev0-V source has a resistance per unit length of $0.0065\Omega/m$. If your apparatus draws 3.0 A, what will be the voltage drop across the connecting wires and what voltage will be applied to your apparatus?
$V_{wires}$    V
the voltage applied to the apparatus is $\approx$    V(Round to the nearest integer)

  Electricity can be a hazard in hospitals, particularly4 ehjv 5fv.-xsjmy08u lwxymn5w0 42o 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 through the mvxy2u45w.j0x0hl- jw4o v5 8ynmfs e 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 45pe9pbn 64vf /o-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 is designed to operate at 72 beats/min usi0 gyw8x) zc+ 3t,p)ety r9t)fppxnd5v ng 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 rejv2s ooz, fyb1 :zup;).kue 0nsistance 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 cikge 1yxuhp-+mlf9 rc: k3,ws8rcuit” used to make measurements of resistance. The unkn:xg 3r1p9hy uke8fk lsw,-c+mown resistance to be measured, $R_x$, is placed in the circuit with accurately known resistances $R_1$ ,$R_2$, and $R_3$(Fig. Below). One of these, $R_3$, is a variable resistor which is adjusted so that when the switch is closed momentarily, the ammeter Ann Meter shows zero current flow.
(a) Determine $R_x$ in terms of $R_1$ ,$R_2$, and $R_3$.
(b) If a Wheatstone bridge is “balanced” when $R_1\,=\,630\Omega$,$R_2\,=\,972\Omega$, and $R_3\,=\,42.6\Omega$, what is the value of the unknown resistance?    $\Omega$

  An unknown length of platinum wire 0.920 mm in diameter i* f ,8r3jjznpgs placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 have resis,*p8nj rjzf3g tance 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 by c 8 hkd+kiwplzr,w. )n9onnecting four identical capacitors, each ha.zrw9w li kn)k 8p,hd+ving a capacitance C?

  The variable capacitance of an old radio tuner consists of founk) , gfun)*obr plates connected together placed alternately between four other plates, also connected together (Fig. Below). Each plate is separated) ,fgn*k )obnu 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 5 k/+c(oz9 fp6fir azlo0dgy6g5;uoxV when 7.40 A is drawn from it and 47.3 V when 2.20 A is drawn. What are the emf and internal resistance of the battery? ao9 +65g6uorp0ziz fx5 ( y;dok /clfg
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 tsiu /iw:.,y wfhe $4.0-k\Omega$ 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 hcz/td-bgncp 42d2 eu 4ili1. capacitor has capacitance $C_0$. If two identically sized dielectric slabs of dielectric constants $K_1$ and $K_2$ are inserted as shown in Fig. 19–64, what is the new capacitance? [Hint: treat this as two capacitors in combination.]

  For the circuit shown in(Fig. Bymkwo3kgnxov47 l ); tk )u(1pelow), 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 when exposbze5wclt f 6,/ed to full sunlight. A solar panel that delivers close to 1.0 A of curre6z ltfcbw5e,/ nt at an emf of 120 V to an external load is needed.
How many cells will you need to create the panel?    cells
How big a panel will you need, and how should you connect the cells to one another?    $m^2$
How can you optimize the output of your solar panel?    banks of    cells in series per bank, with the banks in  ----待选择----parallelseries  always have the panel ----待选择---- pointedturned  directly at the sun。

  A power supply has a fixed output voltage of 12.0 V, but3zn :ma8oraocwh6)w . 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 as in (Fi ) r,7f9h njhxcbigr4hz2lk(-g. Below b). This neon lab)h9rnx 2-i7 ck(4ghh,f j zrlmp 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 thoyg;; 5wrgbdj:0j.kbode)eqz3i13 s 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. Below9gsc v4f5g m6y .s; givbrd)0g/ojm, y), the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalensw1;i eo9fjmo,b +v;a zxg (6bt resistance of the circuit shown in (Fig. Below)? $R_{eq}$ $\approx$    $\Omega$(retain one decimal places)
(b) What is the current in the $18-\Omega$ resistor?    A
(c) What is the current in the $12-\Omega$ resistor?    A
(d) What is the power dissipation in the $4.5-\Omega$ resistor?   W

(a) A voltmeter and an ammeter can be connected as sjygd4n-dj:0l hown in (Fig. Below a) to measure a resistanjjg4 d0ly:dn-ce R. If V is the voltmeter reading, and I is the ammeter reading, the value of R will not quite be $V/I$ (as in Ohm’s law) because some of the current actually goes through the voltmeter. Show that the actual value of R is given by
$\frac{1}{R}=\frac{I}{V}-\frac{1}{R_\mathrm{V}}$,
where $R_V$ is the voltmeter resistance. Note that $R\approx V/I\quad\mathrm{if}\quad R_\mathrm{V}\gg R$ .
(b) A voltmeter and an ammeter can also be connected as shown in (Fig. Below b) to measure a resistance R. Show in this case that
$R=\frac{V}{I}-R_\mathrm{A},$
where V and I are the voltmeter and ammeter readings and $R_A$ is the resistance of the ammeter. Note that $R_\mathrm{A}\quad\mathrm{if}\quad R\approx V/I\quad\mathrm{if}\quad
R_\mathrm{A}\ll R.$

  A flash lightbulb rated at 2.5 W and 3.0 V is 3h- rnp,vqt t dlw2rzc)6n u-1operated by a 9.0-V battery. To light ttht, -r6 2-q)zn1wnrdpcl 3vuhe bulb at its rated voltage and power, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$