Explain why birds can sit on power linesvym ac4/ 5*c t5ptao3z safely, whereas leaning a metal ladder up against a power line to fetch a stuck kite is extremely dangerous.zvm5 a4p o/cay35ttc*

Discuss the advantages and disadvantages of Christmas tree lights confknqpy, /mx,5nected in pa/p ,mxkn qy5,frallel versus those connected in series.

If all you have is a 120-V line, would it be possible to light sever4)5d( pbv5id 1rmldnpal 6-V lamps without burning them out? Hopr1pvm ddnb 5) 4i5(dlw?

Two lightbulbs of resish9d6-y j dsc7stance $R_1$ 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 orm vvqwyw;) xw cpez9);r9z6l) (tms0dd y2 g+l parallel? How do y+lv ;dlq emw()x0wsw9))zyty2g v ;6mpdrz9 c ou know?

With two identical lightbulbs and two n nc0* d 1xxmt:*lx+ssidentical batteries, how would you arrange the bulbs and batteries in a circuit to gend ssxx* + :n*0tm1xlct the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in series to a battery, does the bat:,ufu)a xa+n ptery have to supply more power or less power than wx,+ aup afnu:)hen only one of the resistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the a1qaglphpi2v /p *q2,overall resistance of your room’s electric cirpgpvq2 /lh21,*pi aa qcuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s p4nq2,fop:s mw cm6-s loop rule (such as in Fig. Below), does the sign (or direction) of a battery’s emf depend on the direction ofqo s mw6mscp 2-4:p,nf current through the battery? What about the terminal voltage?

  Given the circuit shownip8 mmh)+ b(u( qnzi.nno*ze c kk0*)y in Fig. 19–36, use the words “increases,” “decreases,” or “stays the same” to complete the followingo* inu yzq ih)p+nkm*z8 ck(.eb)mn(0 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 what use aw. 3j wcl*8jc s*b axa2h)m8oere they connected in parallel? Does it matter if the batteries a8 wjbx3omjlewca*2c. *s) ah8re nearly identical or not in either case?

Can the terminal voltage of a battery ever exceedgp- mkq*;jp yew 8aktx ))jksh519/jb its emf? Explain.

Explain in detail how you coupuu/ -rjawwvg8 ; z/9eld measure the internal resistance of a battery.

Compare and discuss the formulas for resistorsxv lo/5wc(l7 w and for capacitors when connected in se x5lv/lcw o(w7ries and in parallel.

Suppose that three identical capacitors are connected to a battery. Will they sar+ugdj u )dkd7(qw:0 tore more energy if jkwqu)g (+ d ad0rd7u:connected in series or in parallel?

Why is it more dangerous to turn on o 33 a-.vmosjtvj ,-akwyl5nz1*c4ni an electric appliance when you are standing outside j3, vi5vmaw jcz4nt3 kso1 -a-yno*l.in bare feet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condex/3fuki5u7m .g hg c0fffo -6jnser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to move back and forth. Explain how a currekof.gxu fg6uj i f 035/mhf-c7nt of the same frequency as the sound wave is produced.

Design a circuit in which two different s-v x-:7nlwpd+1+rktl-p ma nk witches of the type shown in (Fig. Below) can be used to operate the same lig:pn--+vt7wn mklard +k1x-l phtbulb from opposite sides of a room.

In an RC circuit, current flows from the battery until the c. omu 8-j;msdgapacitor is completely charged. Is the total energy supplied by the battery equal to the tj ;mo.8 dsmug-otal energy stored by the capacitor? If not, where does the extra energy go?

What is the main difanlp7c*kr:i1d b .u 3xference between an analog voltmeter and an analog ammeter?

What would happen if you mistakenly used an ammeter where you needed to u*b n2km uke0yvl-kp0u 0s7 caq81ffh-se a voltmeter?n*uq72v km1hl8pe-0ffbac 0 0s-kkuy

Explain why an ideal ammeter would ha ,nvn+1)dvsefs, ps )3djq9z nve zero resistance and an ideal voltmeter infinite resistance. sfdq)d,) e3npnz jsv1sn +9v,

A voltmeter connected across a resistor always reads lessy.)qyg 76qok z than the actual voltage across the resistor when the meter is not present. Exy. gqy7z 6q)okplain.

A small battery-operated flashlight requires a single 1.5-V b)x(lbqa2i7e z attery. The bulb is barely glowing, but when you take the battery out and check it with ax72l (eb )iazq voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a .6r.4 oteokqock z 6*(8eorbo 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 resist8gq e-m uh21qzance 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 havv h kn l+al3jp9dfs1m+5u ;p9je 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 have9/ur 6xdwgbzk j83r1qf2cws: 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 emzbfd379v8 j 40o*okgt i tp.byf 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 idx2dlmbwn ke6a( q0**,8 niaan 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 connec3m iffpo:rbdem,5+8uted 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 $    $\Omega$   

  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 circui ;ttvp3me43*dpwv k2w t 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 qualita- o;p g8o lpfpuxn5izg:78 ox)tively: 8g )l-ox8pgoxoz;:pfniu7 5 p
(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 circuiuv 1-pn: gs43-w: xjw( vvvw e5vxqxz4t connected to the battery in (Fig. Below)? Each resisx4zw-13: 5exvwg:nu4v-vv (xw svqpj tance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown in (Fi evfu2tfi3 +765vjqu kg. Below). Qualitatively, j+it7e3 2vv5fqf u uk6what 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 that the sum ofcus a27fuedci-zx) .+ all the voltage changes around the c)s-ecc uuf +ax.7i2dzircuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltaga 4jt +ixp 7gigjf4yj.93 9mwje of each battery in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential diu k;)etxmk x)3fference between points a and d in (Fig. Below a) (same circke;)x3ukmx )tuit 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 potentiazp/ow2z,i7 .qxpz+;q h arb r1l difference between points a and b. b/ p2xw a,r 1iqr;+7h.pqzoz zEach resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the u n3s;az37u9wso5abj bsd4ycgg - 7v0un-h0i 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 batterys;x1osyhwh 8nd37 a+e has an internal resistance $r\,=\,1.2\Omega$.
$I_1$ $\approx$    A  ----待选择----leftright (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftright  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftright  (retain two decimal places)

  Determine the magnitudes and directions of the currents in each-kj ghoe -y-6u86ejqg resistor shown in (Fig. Belowg-yj6 - ekogjeu6 -hq8). The batteries have emfs of $E_1\,=\,9.0V$ and $E_2\,=\,12.0V$ and the resistors have values of $R_1\,=\,25\Omega$,$R_2\,=\,18\Omega$, and $R_3\,=\,35\Omega$
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Repeat Problem 29, assuming each battery has internal resista+lv:aeme4t/n l -j4pb nce $r\,=\,1.0\Omega$.
$I_1$ $\approx$    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 h8,o irhil ayr97z o.,of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currents f 8npp30es /dr:x hww.$I_1$,$I_2$, 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 currentufe.5erdq57 m $I_1$ 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 : c5e/wdu6 lzoshown in (Fig. Below). If each iu5:d /cw lzoe6nternal 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 capacitance 3:/2 x uixs amseg;9r/k200 pF, 7500 pF, and $0.0100\mu F$ . What maximum and minimum capacitance can you form from these? How do you make the connection in each case?
$C_{max}$ =    $ \times10^{-8 }\;F$ in  ----待选择----parallelseries 
$C_{min}$ =    $ \times10^{-9 }\;F$ in  ----待选择----parallelseries 

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

  If 26.0 V is applied across the whole network of (Fig. Below)9nc4 m03o+(xmimj y.rsa d5e r, calculate the voltage 95 m x rn40d+scmji.(eo3 ryamacross each capacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of a circuiugt ,tvp1r we vmtz;02)1.sz bt is to be reduced from 4800 pF to 2900 g1 e.v w; ub 2mtz1zsr)tp,0tvpF.
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 constructe(qf7dz;ndgn e 76r h7wd 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 capacitanln2 3c *v p,tuxmcg7d5ce of the circuit shown in (Fig. Below).

  In (Fig. Below), if 9 )3f vlyur3so*esd+ d$C_1=C_2=2C_3=22.6\mu F$, 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), suppoem.136 0iaysnnki :z1 jg4cane .dwd+j0zk e0se $C_1=C_2=2C_3=16.0\mu F$, 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), letbc 4*(yy0pr -moub 1rf $V\,=\,78V$ 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 connw +l4rygr6+g1/6w jq0 diboaq ected as shown in (Fig. Below). 106db r/w+q4i6+qwlg jy rgao
(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 9gt2 u654b0ncvakczoa battery. It is desired to store three times as much energy in a combination 5n4z26koab 0ucvtcg9of 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 connectin9 y i90 md8zojr:fj;ed in series with an unknown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capac i0f;rj: znoj98dm i9yitance?    pF

  Electrocardiographs are often connected as shown in (Fig. Belo63p9ch7uzevu, jix/p w). The leads are said to be capacitively coupled. A time constant of 3.0 s is typp6 phu u i93ecv,/jx7zical 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 resic/xan e* jx1(lstance 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 as Fig. Beiu lta6 t, -r9a,go1umlow 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 a5ovwpn s8;6gtzd5-l;w *o pk3fdzm t6rranged as shown in (Fig. Below). Th; gmp ;z6 dz35*psw nwo-fok8vtltd65 en a potential 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 resistanc-j h3+qt0s9wk 0gar rd .k-hlmo(a,m pe of a voltmeter on the 250-V scale if the meter sensitivity isa r -hg3q-l+9ska,rw0.kd mmt 0oph(j $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sen 68l. nm+uuy*1rjhiuusitivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resistalyt7k x6.tm:tnce 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 sensitivity95 3uxwwtv d0u 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 10cdbvbf(o kb bkvwcd/(,7*j0* mA full scale. It consists of a $0.20-\Omega$ resistor in parallel with a $33-\Omega$ galvanometer. How can you change this ammeter to a voltmeter giving a full-scale reading of 10 V without taking the ammeter apart? What will be the sensitivity ($\Omega/V$) of your voltmeter?
$R_{ser}$ $\approx$    $\Omega$(Round to the nearest integer)
The sensitivity is    $\Omega/V$

  A 45-V battery of negligible internal resistance is c; usw9ex-7ni3/ dgh xgonnected 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 isi g: mt1v092qgjumz9o $63\Omega$ 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 v;9m/ fswdt uu5oltmeter of Example 19–15 have to be in error by5s ;u mutfdw9/ less than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Be-u-aqjyf 4zg7low) 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 differen xsh/klzk 7n4) ror+o;+c*i94cgi pqn ce between two points o c7l iz)n*o xr+no9/+4p sc;r4ghkkq in 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 5f+n(g ro;+r q dek;,fk1z mrg,0 W, 100 W, or 150 W, at 120 V. Such a bulb contains two;f ,(mgq rgdr,ekfnzk+1 r+;o 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 run some apparatus that is 95 m from an electric o olnt:3.zppzmc bl n( 76zv20tutlet. Each of the wires connecting your nz.mv:7( 3b2npl06 lotzptczapparatus to the 120-V source has a resistance per unit length of $0.0065\Omega/m$. If your apparatus draws 3.0 A, what will be the voltage drop across the connecting wires and what voltage will be applied to your apparatus?
$V_{wires}$    V
the voltage applied to the apparatus is $\approx$    V(Round to the nearest integer)

  Electricity can be a hazard in hospitals, particularly to patients who tj *,qu:*n cw(a.m/g 8azjhbyare 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 behy*a8j.z/b( m jgq ,:wnt cau*comes 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 3tcvf tl7v9i:45-V battery expend to charge a $0.40-\mu F$ and a $0.60-\mu F$ capacitor fully when they are placed
(a) in parallel,    $ \times10^{-3 }\;J$
(b) in series?    $ \times10^{-4 }\;J$
(c) How much charge flowed from the battery in each case?
$Q_a$    $\mu C$
$Q_b$ $\approx$    $\mu C$(Round to the nearest integer)

  A heart pacemaker is designed to operate at 72 beats/min 09 6l rqdk,5v9xmofwa 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 bc j5f4mqp e5s t9/n 9ta9.ewudody resistance 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 am me0n .s(.cwl type of “bridge circuit” used to make measurements of resistance. The unknown resistance to mmw.n0(.cl se 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 is placd ,syt e 9v8p2f+9vfuied as the unknown resistance in a Wheatstone bridg tpfdu evyf,9si82v+9 e (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 obtained byi,uv sna1- 38qfkr7sw connecting four identical capacitors, each having a capaci 8w 3knf s,71vuqi-sartance C?

  The variable capacitance of an old radio tuner co*x o:zs1ku , nwje)ec cyp7s/0nsists 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 set of plates can move so that the area of overlap of each platesc*s)jw1 kop ,/:x7yze n c0ue 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 drawn from6qe;*ym+ omi m it and 47.3 V when 2.20 A is drawn. What are the em6*q+ o;mymie mf 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 the k:brgola9w+ ($4.0-k\Omega$ 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 twg,f)/x-;w)h2p u9 jr7el7bp4q.jqdhvn pthas 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), det5-vh 5 b.uiokfermine
(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 o23g /i(tx l0acb*el pan output of 350 mA at 0.80 V when exposed to full sunlixag3c(o 2b0 ltlpi*/eght. A solar panel that delivers close to 1.0 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, b* ncyr/5kin ej88r/san tyk 5x8e8nb2 ut 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 (Fig. Below pybezn)kwx )ss+)3 cn w)zjd(0:a2sxb). Thiss3)ek0sapj:x sc yn)bnw z() )+ dw2xz neon lamp has a threshold voltage $V_0$ for conduction, because no current flows until the neon gas in the tube is ionized by a sufficiently strong electric field. Once the threshold voltage is exceeded, the lamp has negligible resistance. The capacitor stores electrical energy, which can be released to flash the lamp. Assume that $C=0.150\mathrm{~}\mu\mathrm{F},R=2.35\times10\mathrm{~}^6\Omega,V_0=90.0\mathrm{~V}$ and Ann meter=105 V
(a) Assuming that the circuit is hooked up to the emf at time $t\,=\,0$, at what time will the light first flash?    s
(b) If the value of R is increased, will the time you found in part (a) increase or decrease?  ----待选择---- increase decrease 
(c) The flashing of the lamp is very brief. Why?
(d) Explain what happens after the lamp flashes for the first time.

a
b

  The current through the dp. g 37eewk6w$20-\Omega$ resistor in (Fig. Below) does not change whether the two switches $S_1$ and $S_2$ are both open or both closed. Use this clue to determine the value of the unknown resistance R.    $\Omega$

  In the circuit shown in (Fig. Below), th a.( gm0t4 j2ymt6a)bmea+u ihe $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance of the circ9) s 4m)wlsok7yfw 9fgudj+w+uit 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 ammetg h1(7)(n48zoz bfunf crl dj6er can be connected as shown in (Fig. Below a) to measurb1g8 4 (ff)joh7ndzu l6c(znre a resistance 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 operated0 /:fb.vxs hxv by a 9.0-V battery. To light the bulb at its rated voltage and power, a resistor R is connected in series as shown in (Fig. Below). What value: b.vfshx0x v/ should the resistor have?    $\Omega$