Explain why birds can sit on power lines safely, whereas leaning a qzmme*0l rmfr6)vw8g yau 3+,metal ladder up against a power line to fetch a stuck kite isa* mzv+,gl m r6w mye0)ru83qf extremely dangerous.

Discuss the advantagesohxwr. t7d;fz(b y;8 i and disadvantages of Christmas tree lights connected in parallel versus thoso.; wz; x tyfhdr(i7b8e connected in series.

If all you have is a 120-V line, wou*0yw.z:ul d --vpf ezuld it be possible to light several 6-V lamps without burning -* l:-.ewvz uyz0udfpthem out? How?

Two lightbulbs of resistance :fp n- wq+.zcl$R_1$ 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. Arer h/rb, kly +0)bcoe-q these connected in series or parallek0olr,y b +cq h-e/)rbl? How do you know?

With two identical lightbulbs and twr:a/b6/+rbn ntfr, lao identical batteries, how would you arrange the bulbs and bl bnrnf/abr/at+ 6:,ratteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in7./mr5h htr rm series to a battery, does the battery have to supply more power or less power than when only one of ther7 h. m5/rrhtm resistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the overall resigaak8cb 1 u in+fi -*r(z1zsv)stance of your room’s electric circuit change when yorzgv8 c1fz s1+)una k(-ba ii*u turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig/ 2m3iddd;p*t4a1 v oteq,jph. Below), does the sign (or direction) of a battery’s emf depend on 3*md h/ q1,odppajit e; vdt24the direction of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36g*lksupx.j.q9gm* 1 rk4m78a vy2mhm, use the words “increases,” “decreases,” or “stays the same” to complete the foamlrv9g x2pjqh8.k m 4*ys7k1 *m.m gullowing 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 what9vzq g 0huj,*y use are they connected in parallel? Does it ,guzvj*h 0 qy9matter if the batteries are nearly identical or not in either case?

Can the terminal voltage of rfa.. 2 dstpuj8k8 (pna battery ever exceed its emf? Explain.

Explain in detail how you could mealjq; lsp 7t)+wsure the internal resistance of a battery.

Compare and discuss the formulas for resisj1 *8p xznah5gtors and for capacitors when connected in serieaj 5n*8 zphx1gs and in parallel.

Suppose that three identical capacitors are connect wr0ddyg2p51 zed to a battery. Will they store more energydryz 5pd2w10 g if connected in series or in parallel?

Why is it more dangerous to turn on an electric appliance 5x i +3h;iu1qw6qtw5(us ogcswhen you are standing outside in bare x+s iqg 51( hos wi5cu;wt6q3ufeet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphone. The ct 4e4ch5 i:a1zi3mbjb hanging air pressure in a sound wave causes one plate of the capacitor C to move back and forth. Explaib aj:1i4ctz b3 5mei4hn how a current of the same frequency as the sound wave is produced.

Design a circuit in which two different switches of the:meh23ia pq/c type shown in (Fig. Below) can be used to pah q2ime: c3/operate the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from the battexsgau06kuj1o yia ;*wb:sz 4 8ry until the capacitor is completely charged. Is the totalb* o:0 8j6kaai;ug4xyuw 1szs 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 difference between an analog voltmeter and an a uk;+r+xef,f- b)dd fnzov,: ynalog ammeter?

What would happen if you mistakenly used an ammeter where you needed to uses4;rnb5v 3syya*gwsz(vt +( 2 ko:e nx a voltmt(5eyz+w nb(a4:v3 2rng v;*yxssso k eter?

Explain why an ideal ammeter would have zero resisto 2e4t--pet*n 6bkitw cnqf2ie 8p v)/ance and an ideal voltmeter inbee-n22woqfc)pv*kt ie64/t ip8n- t finite resistance.

A voltmeter connected70dd/ mjbpea zb o8c93 across a resistor always reads less than the actual voltage across the resistor when th0b eb/8dcom d3 9zpa7je meter is not present. Explain.

A small battery-operated flashlight requires a single 1.5-V battery. ir05x 57hg:jffirw/lThe 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 explar07 f5iw g5ix/rj hlf:in this?

  Calculate the terminal voltage for a battery wa+r/iez,)oj*( tp9g )ko gstwith 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 rge z /97d26h3bpm (q(cwx chztesistance 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 hav6a dxp* zj5zr(e a $680-\Omega$, a $940-\Omega$ and a $1.20-k\Omega$ resistor. What is
(a) the maximum,    $\Omega$
(b) the minimum resistance you can obtain by combining these?    $\Omega$

Suppose that you have a 4;oj:txnk a-04 vbbvt $6.0-V$ 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 emnv+n qv4u pw ow47o4:rf 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 c,* ie*ixbp4,k 4 60n xt pmvxw:skesubtn)8/yonnected in series across a $110-V$ line.
(a) What is the voltage across each bulb? V$\approx$    V(Round to the nearest integer)
(b) If the current is $0.50\,A$, what is the resistance of each bulb, and what is the power dissipated in each?
R $\approx$    $\Omega$(Round to the nearest integer)
P $\approx$    W(retain one decimal places)

  Eight lights are connected in parallel /6 d/ -sulvv/+q1ifktft v1 ozto 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 circuit reveals t.bg7l4toa8 pn hat 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). An- va t7jidi;(3 0xuerdswer qualitatively: j0a;-3xu ii( d edrt7v
(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 bat 7no fxx06+j5oof p2qttery in (Fig. Below)? Each resi tn xx op760qo2jff+o5stance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are conne r 1mks;ychyn)m+)ftnj k,z; *cted to a battery as shown in (Fig. Below). Qu1rm fct kyjyzn)s,n;*;mh)k+ alitatively, what happens 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 t8pd ah1xzw: *:fe,-pgfvgy7w hat the sum of all the voltage changes ,-pp a x8z:: ggwdyvffh7e*1waround the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal voltage of ex,m*2+e-vzrvztf : yd(+v d au0cib6jach battery in (Fig. Below). 18V battery =    V 12V battery =    V

  (a) What is the potential difference f+n lgg4nn5f13itja:ab lk.6 between points a and d in (Fig. Below a) (same circuit as Fig. Below b, 5g gjfn +4fi .nk6tnl:baa3l1 ), $V_{ad}$    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 differe s3f t+lu w+ (nal7ntre4gk65snce between points a and b. Each res3rfa(el t7n 5g6lust+ +k s4nwistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes,x f18 ahhj gm;ooeoy li)k+zl234*my and directions 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 hhs:rkf(q:2 vb p koyaql58i:f +*3sjthat each 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 a2ubgb p.j44;m(5ka6l ka8 ippt )rbe0pdo:cp nd directions of the currents in each resistor shown in (Fig. Below). The batteries have emfs o2;lk :5jrci. b )o4ga epb84( mpatupbk06 ppdf $E_1\,=\,9.0V$ 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 in4nx.n p8hr a4,sidjg, ternal resistance $r\,=\,1.0\Omega$.
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Calculate the currents in each resistor nf ceg28l7ta (/i v)y0x7fuzg of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curre c+(z6mll3r+a)m i jmvv bey,rq2-im+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 curre e/0s /abx:ab+y,xr5nbd y(punt $I_1$ 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 as thj- whrfyz kzsh0 +m. x72(+dshown jzdz0+xsf2 t y(w.h-r+kh mh7in (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 capacitaii9o4a u ku7s3nce 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 /ls)w kpd2uyp 7x02ed(Fig. Below), calculate the voltage acrossdlkpp)/72wsux 0d y2e each capacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of a circuit is tof*94 /i82 bos +qc8rbnyif6qy 3nafvo be reduced from 4800 pF to 2900 pFobfi 893vyoc 6i8f+q n*4sbynraf/q 2.
What capacitance can be added to the circuit to produce this effect without removing existing circuit elements?    $ \times10^{ -9}\;F$
Must any existing connections be broken in the process?  ----待选择----YesNo 

  An electric circuit was accidentally constructed usif1ov/qy(2 mf yng 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 capacitance of the circ uo 6 d;w,v1svkwaje7;uit shown in (Fig. Below).

  In (Fig. Below), if x7ni ;d.rzgxe8r- ufxu jq1;- $C_1=C_2=2C_3=22.6\mu F$, 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), suppos xfq*k.k jv33ss4: lqe;bbzh 9e $C_1=C_2=2C_3=16.0\mu F$, 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 gy jpb +cdknx./44 :sy$V\,=\,78V$ 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 ( u tvsp +zk)w9b j:+sf9)mo4oaFig. Below). kaz4p))bu+:oj sts9m+f vow9
(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 ak s.ix 08f.x xdxv;ashoal( (7 single 250-pF capacitor hooked across a battery. It is desired to store three k8a xv(7.idxhf x o(axs.;l 0stimes 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 with an un4ikhs13xn e;8g -q azjck8qm7known capacitance, and as a series combination they are connected to qiqsn4g3m;kzh-c7ke8xj 8a 1a 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 oxz. i2hll+k ne xx--q2ften connected as shown in (Fig. Below). The leads are said to be capacitively coupled. A tii x - +hnxkl2l2eqz.-xme constant of 3.0 s is typical and allows rapid changes in potential to be recorded accurately. If $C\,=\,3.0\mu F$, what value must R have? [Hint: consider each leg as a separate circuit.]    $ \times10^{6 }\;\Omega$

  In Fig. Below a (same as Fig. Below bmb y+2xz4 an-vlq63ry ), 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.cbd q ;p//t-ay Below a (same as Fig. Below b) has $R\,=\,6.7k\Omega$ and $C\,=\,3.0\,\mu F$. The capacitor is at voltage $V_0$ at $t=0$. when the switch is closed. How long does it take the capacitor to discharge to 1.0% of its initial voltage?    $ \times10^{ -2}\;s$
a
b

  Two resistors and two uncharged capacitors are arran5 lxd i nn cwpw6;kh4;:e3svm3ged as shown in (Fig. Below). Then a potential difference of 24 V is applied across the combinatn c en;pvx 3k3l 6d:iww;45mshion 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 resistance38 9yuqbp43cqw ve)uk of a voltmeter on the 250-V scale if the meter sensitivitqv cupkq e9y83w)3u4b y is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivitylmj74p 3ga4 yq of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resistances7uynz i..sdc0gp( 7-du a+g8xyh m1 x 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 sensit-4dif2g;hl2i fn me xeld (e-c,(4 eh(-mmdqnivity 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 mow4rkiga p.8 6reg3vk fv-8.w A 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 connec(vl lmrh )w2gmps x;;4ted 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 res0 7vwi-:qzka m)r pwt1/jzci7istance 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 resistancl 3a4dld;ziu* 6pa -gl3ni1pre should the voltmeter of Example 19–15 have to be in error by less than 3%? p irp*z 1lgan436l3iudl-da; $\approx$    k$\Omega$

  When the resistor R in (Fig.;y2h1qehe9ngz ; td .e 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 pot;.a:y tdfa 3n.j;vb vrential difference between two points on thea; d:y3vrj.tb; vf .an 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 W, 103y--d xgd0 ;93zia a;dceqtjo,8hhig0 W, or 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually or in p;ahddti-h; o jgzde9 x303ag8iqy c-,arallel.
(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 someh( o6v4 g1d rlyd j1-+,covbck apparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 126kdo rb oc(,lv+ h-jyg1 1vcd40-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, particularly to patients who aj0c zshgg408 lm 3ftaj+h 68odre 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 h+cdml4tsg a h 008z 3g8oj6jfa 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 45odqm; llc6n:(f,ypx 4-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/moif+*x)t5*a nodmyq -in 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 resista7(s oh:ek8tb pnce 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” user:u1o m:pl(zm6( ffojd to make measurements of re zo pmfo1lj:(u(6 :mrfsistance. The unknown 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 plati); ijlb*6y,dgll wv2f* -3ox-nuwgy xnum wire 0.920 mm in diameter is placed as the unknown resistance in a Wheatstone bridge f;dvgyxin-*3y*,ub6ow- 2 wl gxllj)(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 obt lipra s2)0n)c;9wcr / bhr5bgained by connecting four idws bachn0l ;r5 ) cr)pgr/2i9bentical capacitors, each having a capacitance C?

  The variable capacitance of an old radio tuner consists of four plates ci jysu6mdep2c+x 5n7bl f 9r8k:nx; 8gonnected together placed alternately between four other plates, also connected together (Fig. Below). Each plate is separated from its neighbor byxem8x5b+8cdysg k pn6n7j9:;rufi 2l 1.5 mm of air. One set of plates can move so that the area of overlap of each plate varies from $2.0cm^2$ to $9.5cm^2$
(a) Are these seven capacitors connected in series or in parallel?  ----待选择----parallelseries 
(b) Determine the range of capacitance values. from    pF to    pF

  A battery produces 40.8 V when 7.40 A is draw rgc4 oe3z8-dwv 8ndac+bwo(*n from it and 47.3 V when 2.20 A is drawn. What are the emf and internalr o84dwc3gaz(ocn + db-8*vwe 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 the o pa;/3wqs(u) m0emkb$4.0-k\Omega$ 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 capacitor has cap r,quhz6n5gl*t ;d,bpy52wteacitance $C_0$. 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), detezalt4bf8-;dq po7 8fdrmine
(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 b,c 7au4i2 x +,/nybxnhbt2/ zgyo.zr0.80 V when exposed to full sunlight. A solar panel that delivers close to 1.zx gbtrzi4byo.yb+/xa 2n/ ,h u72nc,0 A of current at an emf of 120 V to an external load is needed.
How many cells will you need to create the panel?    cells
How big a panel will you need, and how should you connect the cells to one another?    $m^2$
How can you optimize the output of your solar panel?    banks of    cells in series per bank, with the banks in  ----待选择----parallelseries  always have the panel ----待选择---- pointedturned  directly at the sun。

  A power supply has a fixed output voltage of 12.0 V, but you nl2)le(j kvy)c eed $V_T\,=\,3.0V$ 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 (Fig. xnmx vrg h 0*x 9o.h5lb)-j4jrBelow b). This neon la5)xl 4x-jvh b gnor09x rhm.j*mp 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 thenfgyd qqe 8m:uim5 *9* $20-\Omega$ 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 (wj0l u8o upy-5 rzejwt;/d s((Fig. Below), the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resk )ef i;fcw.c+istance 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 shownpiy4h0,1 jhc.xd7ft bk8z8ks in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeter reading, the valueytc h7hf8ikp1 .zdbk0 8 x4j,s 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 m(sku v ,oypk yxdu8(5uqk.,1operated by a 9.0-V battery. To light the bulb at its rated voltage and power,(md,ks8puko ykx5.uqyv 1u, ( a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$