Explain why birds can sit on power lines safely, where ly3m)(mccol0 as leaning a metal ladder up against a power line to fetch a stuck ki) o0mylc lm(c3te is extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree terhl: h7t 74elights connected in parallel versus thl4t7hhrt7:e eose connected in series.

If all you have is a 120-V line, would it bcvqjk, lpj r9xmb7xc 4br..70e possible to light several 6-V lamps without burningvcrqlcr7kjp,xbmj7. 4b.9 0x them out? How?

Two lightbulbs of resist+ yqkf:m(2j oe(q g)a0inw reu1x ,3txance $R_1$ 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 *6lb2 z u*afbqseries or parallel? Hobuz**a2l6f q bw do you know?

With two identical lightbulbs and twouxc -3w.*btwp(fqp /d identical batteries, how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume the battpqx(/ctwd p.- w* u3bferies have negligible internal resistance.)

If two identical resistors are connected in series to a battery, does the ba)ln isrgy0u -bi.z4ji 8 48sk9njx7l zttery have to supp8iijs8xgkbi.4nl-zl jzy9r ns 047u)ly more power or less power than when only one of the resistors is connected? Explain.

You have a single 60-W bulb on in your room. Ho7pjcenfu 4-s8n8xqgfo73or 9a j)b-tw does the overall resistance of your roomp8jr9ogxb -eus-n qcf7)37a ot 4njf 8’s electric circuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below), does the sign (o(j +tnon( sty8a: srs/r direction) of a battery’s emf dep y 8/(sanns r+sjtt(o:end on the direction of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–he yw/. y 7s9.n*g*rorwifs8 a36, use the words “increases,” “decreases,” or “stays the same” to s/ 8o7w *n eh*i.rys wyra9fg.complete the following statements:
(a) If $R_7$ increases, the potential difference between A and E  ----待选择----stays in samedecreaseincrease . Assume no resistance in Ann meter and power supply.
(b) If $R_7$ increases, the potential difference between A and E  ----待选择----stays in samedecreaseincrease . Assume Ann meter and power supply have resistance.
(c) If $R_7$ increases, the voltage drop across $R_4$  ----待选择----stays in samedecreaseincrease .
(d) If $R_2$ decreases, the current through $R_1$  ----待选择----stays in samedecreaseincrease .
(e) If $R_2$ decreases, the current through $R_6$  ----待选择----stays in samedecreaseincrease .
(f) If $R_2$ decreases, the current through $R_3$  ----待选择----stays in samedecreaseincrease .
(g) If $R_5$ increases, the voltage drop across $R_2$  ----待选择----stays in samedecreaseincrease .
(h) If $R_5$ increases, the voltage drop across $R_4$  ----待选择----stays in samedecreaseincrease .
(i) If $R_2$,$R_5$, and $R_7$ increase, power supply (r = 0)  ----待选择----stays in samedecreaseincrease .

For what use are batteries connek* /pmj+yf2q-1smymnp+ y)ek cted in series? For what use are they connected in parallel? Does it matter if the batteries are nearly identical or no+/kmnqmm*p)-y+sy ef k2jy p1t in either case?

Can the terminal vol2b , tc or(+gw,bcwc2jtage of a battery ever exceed its emf? Explain.

Explain in detail how you could measure the internal resistann9;/b0cz y wfa3 6ssersu 9q(oce of a battery.

Compare and discuss the formulas for resistors and fokj2 0yd9bguu;zoq0 x8 r capacitors when connected in serie8 uq020ub; kx9jogy dzs and in parallel.

Suppose that three identical capan.+pu8 ;p*k:ehv2 x dvwz) sylcitors are connected to a battery. Will they store more energy if connected sk2vh . ;e:l+zy8 )*npuwvpxd in series or in parallel?

Why is it more dangerous to turn on an electric appliance when you are stt w ,9rv9w0: s5*g)wftfn oam+p(kkweanding outside in bare feet than whra9,(9n:+mvtg)o w kfktf5 w w*swe0pen you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of: m; )wexbmfhx (0cqc/b.3ar j a capacitor (or condenser) microphone. The changing air .q)f0c b hxr mj3 ;/xw:a(ecbmpressure in a sound wave causes one 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 of the type shown rxkl*41 k udq *hru5b.4v-rdq in (Fig. Below) can be used to opek* xbrdv*r q54-d k uh41uqr.lrate the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from +j-u0+ l5jf ixp7wlnpz cncueeh6qt;y //* :jthe battery until the capacitor is completely charged. Is the y/*jji:f7 u pqhzt-60 ;nxwlnp5cu+ ecelj/+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 difference between an analog voljeq-m0l qc ish)3tl/5tmeter and an analog ammeter?

What would happen if you yvq8s5yg):/8 t,to d nh+aawxmistakenly used an ammeter where you needed to use a voltmx8) h: /y+dgs5yaw8 onvttq,aeter?

Explain why an ideal ammeter would have zero resiae82bc -wzh -kstance and an ideal voltmeter infinitezk -cew28hab - resistance.

A voltmeter connected across a resistor always reads less th yu s45el*5nxman the actual voltage across the resistor wheney5l*n su x5m4 the meter is not present. Explain.

A small battery-operated flashlight requires a single 1.5-V batlcd ye, f4kxusai)2./ tery. The bulb is barely glowing, but when you take the battery out and check it with a voltmeter,e.xauys /l,i )f2dck4 it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an internal resistjukb 3l et7n 1,bp:nsl; 5.gisance 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 resi siud, rk;4fg4 uzv)n4stance of a $12.0-V$ car battery whose terminal voltage drops to $8.4\,V$
when the starter draws $75\,A$?    $\Omega$
What is the resistance of the starter?    $\Omega$

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

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

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

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

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

  Suppose that you have +r8*l9evh q-*ubwz hra $680-\Omega$, 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 awe4 5tr*67aiv x lk2yh $6.0-V$ battery and you wish to apply a voltage of only $4.0\,V$. Given an unlimited supply of $1.0-\Omega$ resistors, how could you connect them so as to make a “voltage divider” that produces a $4.0-V$ output for a $6.0-V$ input?

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

  A battery with an emf h.v0xf2vux e ,d/xp c0of $12.0\,V$ 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)* 3 yemr3vbujk(kj 2n7w70q biah-iy are connected 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 parallu5ii ,r/)yevl 8shp m:el to a $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?
$V_R $ =    $\Omega$
firaction wasted =   

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

  A close inspection of an ere-1i7w-46seb g+6uq pf ht gglectric 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 (F3i f4r8 rshzmda)3dw0es z6l( ig. Below). Answer qualitatively: a 3(i68szdzrws4m ) 03ldhref
(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 cird/ ) c:sw-hgazcuit connected to the battery in (Fig. Below)? Each resistance - )wsd:acg/h zhas $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (l+-v9q :*hdsgg 9 dlt.td olt9R) are connected to a battery as shown in (Fig. Below). Qualitatively, what happens to dlolgtvg9s*h:-d +q9 ttd9 l.
(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 (Fizaetls y*j 7kn/4.8mjg. Below) and show that the sum of all the volta m teank4l7/y.8zjj *sge changes around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal voltage of each battery in (Fig. Below). 18V bat ly+gwpvv01 y:tery =    V 12V battery =    V

  (a) What is the potential difference between points a and d in (Fig. Below a) ((i7 8sznrp u3m mikk7;same circuit as Fig. Belowkur7iki ;7n sp3z( 8mm 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 (Figw3iji4 k 0le rp-fww64. Below), find the potential difference between points a and b. Each 6kw4 pl-j4 fiw3rw0ieresistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnittes-dq) i ubj 22m62xc )+e sl1e:iatkm7l*gqudes 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, noq; ,zwsm4 w/kww assuming that 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 and directions of the currents in each resistor showbz x-qsq-ga(( -0aolh n in (Fig. (sqbzh l-(a-oax-g 0q Below). The batteries have emfs of $E_1\,=\,9.0V$ and $E_2\,=\,12.0V$ and the resistors have values of $R_1\,=\,25\Omega$,$R_2\,=\,18\Omega$, and $R_3\,=\,35\Omega$
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Repeat Problem 29, assuming each battery has internal resistaihfn7jy25ms j)xn ;+nsgz8tzid8 ) 0pb:,d ahnce $r\,=\,1.0\Omega$.
$I_1$ $\approx$    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 of (q*t6fn(d0i/jyml-8a t w c3us d5j 2fsFig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curre4 rtrkoc u yf01t52(ugnts $I_1$,$I_2$, 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 ; -i n)9ttl,g lmmduk7$I_1$ 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 f6 f uv+ qh8pp(5hsb+f8 2uzusshown in (Fig. Below). If each internal resistance s5uz6q+pfb8fs8 u(p + fuh2hvis $r\,=\,0.100\Omega$ 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 ca f84zuecx +4hy7ga5rspacitance 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 s ,0kci j6mtbm n; zvt2ses*,;of (Fig. Below), calculate the voltage acr 2ntv0;s*mz;s6t, ,sikbjecmoss each capacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of a circuit is to be reduced fwah43 /ei vm5yq5i.gfidmat9+) aq ; wrom 4800 pF to 2900 pFiv9m5hiymq)t f w aqd.eia3;wg/5+a4.
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 constr xua7:w qt0nisl nya +.de0*i1ucted 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 capacitance of the circuit shown ncl -)v6j9 zcxh8so /fin (Fig. Below).

  In (Fig. Below), if yaoh6/vk5ydj *3 um v4syqz25$C_1=C_2=2C_3=22.6\mu F$, 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), suprx*kmwz-aw 9bu6xmd )51a1r rpose $C_1=C_2=2C_3=16.0\mu F$, 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), letd*yhqt+7 qe 2qf1v g,i $V\,=\,78V$ 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 o yr2e ,orzn.j15o 3c:13nv0sy v,tojwcij2j cf area A, are connected as shown in (Fig. Below).3c,23zo:o .v on ,1ejtrj yjij0n5 w1vscrc2y
(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 caueyf :cr4ps )2pacitor hooked across a battery. It is desired to store three times as much energy in a combin y4)2esfr :cupation 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 uiz:m /(xw6bmconnected 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 iwzbu/x :6mmi(s the unknown capacitance?    pF

  Electrocardiographs are often connected as shown in (Fig. Below). The 2hwv0v6ea 7d9w yj-rmwf m.m :leads are said to be capacitively coupled. A :h.2 ewm j6v -r0vfwamw79dmytime 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 b), the total resis6x3qc ol,smqtal7p1x:d42kp /urzc* tance 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. Be++0n minzve nh*vdbaq3 :h2o)low 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 arrang foxv+. fgip+5ed as shown in (Fig. Below). Then a potef ++ f5ixgov.pntial 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 a voltmeter on the 250-V scale if the meterv,c-0 gaia 9y9ozc2:np zvo*a sensitivity ig9c:2oc,90p*va zvo - iaznya s $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a senrcm4w9kjum) b b/-mt;sitivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resis, bcfc*a+er: rtance 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 aat/-tdge.w lplo /m( 1 sensitivity 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 consix3hbzpu 3e 3hcg6i blr9x2h 51sts 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 neglir* 60xkdcxo1l9 b3i0k.p dkingible 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 intejaluz+y a3);(tlei6pqz + t k*+.* ifx(lyypbrnal resistance is $63\Omega$ reads 5.25 mA when connected in a circuit containing a battery and two resistors in series whose values are $750\Omega$ and $480\Omega$. What is the actual current when the ammeter is absent?    $ \times10^{ -3}\;A$

  A battery with $E\,=\,12.0V$ and internal resistance $r\,=\,1.0\Omega$ is connected to two $9.0-k\Omega$ resistors in series. An ammeter of internal resistance $0.50\Omega$ measures the current, and at the same time a voltmeter with internal resistance $15k\Omega$ measures the voltage across one of the $9.0-k\Omega$ resistors in the circuit. What do the ammeter and voltmeter read?
$I_{source}$   $ \times10^{ -4}\;A$
$V_{meter}$    V

  Two $9.4-k\Omega$ resistors are placed in series and connected to a battery. A voltmeter of sensitivity $1000\Omega/V$ is on the 3.0-V scale and reads 2.0 V when placed across either resistor. What is the emf of the battery? (Ignore its internal resistance.) $\approx$    V（Round to the nearest integer）

  What internal resistance should the vopyb9cm g-j0 ;qt8:xcm dbgi ;,ltmeter of Example 19–15 have to be in error by lei;0c;dtx8pg jb m-bm :9g, qycss than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig.; 7s6q oobsgb; js)zhyq ur8+. 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 potentw7jpj.)jqr6 6p m2l1hp5r jar ial difference between two points on the huj51.q7jwjrar p 2rm6ppjhl)6 man 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, 100 W, or 150 W, at 120 V. Such a bulb c:czl pq .uhu-l14yue *ontains two filaments that can be connected to thelu c: u.4q*lz1-euhyp 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 apparatuskjh *rv:; :ocule3 d8t that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 120-V source t*dhj rl :co8uv k:;3ehas 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 pak/2id lghi ;*oo)q ag,tients 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 ECG appar*)io; g/godal2kq h ,iatus. This is shown schematically in Fig. 19–60. Calculate the current through the patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must a 45-V ds xg7sbx ,l,5battery 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 nj(a)12d d1zsko1 ivi beats/min using a $7.5-\mu F$ capacitor in a simple RC circuit. What value of resistance should be used if the pacemaker is to fire (capacitor discharge) when the voltage reaches 63% of maximum?    $ \times10^{-5 }\;\Omega$

  Suppose that a person’s body resistance iipjhdd: *b;/l s $950\Omega$
(a) What current passes through the body when the person accidentally is connected to 110 V?   A
(b) If there is an alternative path to ground whose resistance is $45\Omega$, what current passes through the person?   A
(c) If the voltage source can produce at most 1.5 A, how much current passes through the person in case (b)? $\approx$    mA(retain three decimal places)

  A Wheatstone bridge is a type of “bridge circuit” used toc23joqynb og qvqy5,+z fk ; /gu95*ni make measurements of resistance. The unknown resistan z9fni3y,b o2 qqg 5ocgj k+/nvuy;q5*ce 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 is placed as the unkl;y 93k6lbgl nnown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 hn6; 3ykb9l llgave 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 by connee;iw) /j- :ojqwlsu/ gcting four identical capacitors,jiu-/ q/:wowl )gjes ; each having a capacitance C?

  The variable capacitance of an old radio tuner consists of four *2.oh:,sisbe v (f v2y2ajiivplates 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 *v aj s bive2ov.sh(2:y,2fiiof 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 -e4) g2tzzzt 9a13uf+ ducsqvdrawn from it and 47.3 V when 2.20 A is du+ze4v)1zq-s 9t3cft 2 dg uzarawn. What are the emf and internal resistance of the battery?
r =    $\Omega$
$\varepsilon$ =    V

  How many $\frac{1}{2}-W$ resistors, each of the same resistance, must be used to produce an equivalent $2.2-k\Omega$, $3.5-W$ resistor?    $\Omega$ resistors, each rated at ½ W, in  ----待选择----seriesparallel 
What is the resistance of each, and how must they be connected? Do not exceed $P\,=\,\frac{1}{2}W$ in each resistor.    k$\Omega$ resistors, each rated at ½ W, in  ----待选择----seriesparallel 

  The current through ther7ts slw0f 3ppzj ))e7 $4.0-k\Omega$ 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 capab, pxb82mzw;s citor 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. Belowm19 qc31xg eszcnc0)y), 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 o(h ,rvp;5b cdbb8 3fjm+b,glh f 350 mA at 0.80 V when exposed to full sunlight. A solar panel that delivers close to 1.0 A of current at an emf of 120 V to an external load bjr hcb+( 5m b,vfl;bhp,g3d8is 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 out k 2h4i+3,b*n quysin:xq5efsput voltage of 12.0 V, but you need $V_T\,=\,3.0V$ for an experiment.
(a) Using the voltage divider shown in (Fig. Below), what should $R_2$ be if $R_1$ is $10.0\Omega$? $\approx$    $\Omega$(retain one decimal places)
(b) What will the terminal voltage $V_T$ be if you connect a load to the 3.0-V terminal, assuming the load has a resistance of $7.0\Omega$? $\approx$    V(retain one decimal places)

  The circuit shown in (Fig. Below a) uses a neobjhoi58j0 bfop33d v7n-filled tube as in (Fig. Below b). This neon lamp has a threshold voltafp5dhibb 8voo3j j703ge $V_0$ 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 rhwv- wz cmum r4c724(v2ie+z the $20-\Omega$ 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), u3q :tmri71le lt c*7bthe $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance of the circuit shown in (Fig. Below)t5.: 4 yhfn*ibbfv2st? $R_{eq}$ $\approx$    $\Omega$(retain one decimal places)
(b) What is the current in the $18-\Omega$ resistor?    A
(c) What is the current in the $12-\Omega$ resistor?    A
(d) What is the power dissipation in the $4.5-\Omega$ resistor?   W

(a) A voltmeter and an ammeter can be connected as shown in (Fig. Belozvh8-r ks3*nw w a) to measure a resisw *z3vshnk r-8tance 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)4tga( d c-j tdpb/6nw W and 3.0 V is operated 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. Bebcgjw d p )6dtna-/(t4low). What value should the resistor have?    $\Omega$