Explain why birds can sit on power lines safely, whezh18 +m+ xvonqoq(ue)reas leaning a metal ladder up against a power line to fetch a stuck kite is extremely dq(hqzn1mo ve8++) ox uangerous.

Discuss the advantages and disadvantages of Christmas tree qs * yd hli1oc41chbkt+f-3k.lights connected in parallel versus those connected in 4s1-okdck. b fi3h l*qy+1hct series.

If all you have is a 120-V line, would it be possible to ligh:sc: xlemn t44r p9c4ss*(nf lt several 6-V lamps without burrxs4fe*:tsmcpsl4 (:c n94n l ning them out? How?

Two lightbulbs of reui3+g p3o d:twrza r9s0+q a3esistance $R_1$ 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 a3:k4 v9qsria or parallel? How do you know?34a:v9 r qaisk

With two identical lightbulbs and two 22i2.hurvv isi.e+f pidentical batteries, how would you arrange the bulbs and batt2ip i.+vi. u r2fsve2heries in a circuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in seriek4xiq* hj, -jzs to a battery, does the battery have to supply more power or less power than when only one of the re q4*hz-ij ,xjksistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the overall resistance of k 1g+31xycs wkxp1.qpyour room’s electric circuit change when you turn on an.113wsc+yxqx 1kpp g k additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below), does the sign (,(ay,07-r rnaz ffozx or direction) of a battery’s emf depend on the direction of current through t,oyrrzz - a,xfn a7(f0he battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use th u3qtj:qxs g+0e words “increases,” “decreases,” or “sjtus0 x:q+q3 gtays the same” to 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 connected in series? For s4 q11s-; aizo d:fbgfwhat use are they connected in parallel? Does it matter if the batteries are nearly identicalod4 f f-sz:;i s1q1bag or not in either case?

Can the terminal voltage of a battery ever exceed id7qkb)b6(6a1wrdjkpl ld1;g5n*(f3x enf s tts emf? Explain.

Explain in detail how you could measure the internal resistance 1bvajfw7f6. 9oie1rx of a battery.

Compare and discuss the formpwy 7m 2forvueit r 5/9y/r:)tulas for resistors and for capacitors when connected in series and in parallerrov//ieurm9 )yf:p57 w y2ttl.

Suppose that three ix7ok0ww6 n.9h 0chhcw +k7rx.q3 xq sodentical capacitors are connected to a battery. Will they store more energy if oqwxh7hc9.xrn wskqk wo.3 x+ 6h700c connected in series or in parallel?

Why is it more dangerous to turm c c5(bd .ll9nj,xwc8n on an electric appliance when you are standing outside in bare8n9xj lcd,bc(. wcml5 feet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphn67duw/)y;3a yn (imwfx b lh(one. The changing air pressure in a sound wa;ywadfh n3 n()7/xybmuw(6li ve 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 tyjbnr,zv-st,ef ow( ),pe shown in (Fig. Below) can be used to ope-,n)zb fetvr w,s,(ojrate the same lightbulb from opposite sides of a room.

In an RC circuit, curreniyg 16i o rsyh *tuc2-s1 :cu)ltx/t9nt flows from the battery until the capacitor is completely charged. Is the total energy supplied by the battery equal tcti y1ocr ux*ntyli-)h 2 u/s1t6s9:go the total energy stored by the capacitor? If not, where does the extra energy go?

What is the main difference between an analoge ff w z(0j0qw 8*m-q;y; nkpw6bti;qu voltmeter and an analog ammeter?

What would happen if you mistakenly used an ammer5y,p(ax nn f)ter where you needed to use a vofr nxnp(y, 5a)ltmeter?

Explain why an ideal ammet +:0sezlnd8o2rr j; uier would have zero resistance and an ideal voltmeter infinite resistjns: zdr+ 0 le2ru8;oiance.

A voltmeter connected across a resistor always reads less than the actualo*nn94 dv3ex*i, cgad voltage across the resistor when the mete,ona*i d3nx *e vd4g9cr is not present. Explain.

A small battery-operated flashlight requires a single 1.5-V p; w+ 4of7pml7eys2ly battery. The bulb is barely glowing, but when you take the battery out and check it with a voltmeter, it registers 1.5 V. How would you explain thy4ls; y7f7+po2 lwpe mis?

  Calculate the terminal voltage for a battery with an internal reegbrl qw/t)e+(po3-amym:;t sistance 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 resistan,d9k7v.:f q bz wa7vbnce 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 havet 8z dsi9a rd,3,9aala :itkc8 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 q6vv4iq2ek jt6f;1thsg+ j4a $6.0-V$ 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 emfm*09:l(wd e ts.qqs sb 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 lighlbea2a,5 w7 dgmc+nc a6 4dd)cts 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 para:rq )h+ a fhwbcz9fg.gjy(2t*llel 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 circuit reveals that a t(g).. gw9sy 1v ropn4k df5zynm2nn5 $480-\Omega$ 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 h4o/ycs2is.lyql, . oof resistors shown in (Fig. Below). Answer qualitatively: yo 2cl.4 is.lh/q,osy
(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 c( -g:w c.v9lmm jd6ziuonnected to the battery in (Fig. Below)? Each ri(cug ljw-:9vdm6.mz esistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown in (1khv/ t5uiwtr/2 )jmuFig. Below). Qualitatit5 1hir)tuv/mw j/u2kvely, 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. Bep/o2 j1ps mfe.low) and show that the sum of all the voltage ospfm.j21e / pchanges around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal *j8,x cuq. ktpvoltage of each battery in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential dif6si52*9h2 b xw55p jndzgpz( lv9g tqhference between points a and d in (Fig. Below a) (same circuit as vzbni2xq p 59h ( d j6pwz9*t5glgh25sFig. 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 pgiqd xx+(zp (x4o2m9 potential difference between points a and b. Each res9xgqid2x4 o+(xz mp(pistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the currents throu u0n:a7z+kvk;j.afll gh $R_1$ and $R_2$ in (Fig. Below). $I_1$    A  ----待选择----leftright  $I_2$    A  ----待选择----leftright 

  Repeat Problem 27, now zx3h54tz71bvc qy-l h 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 sho;fu r 3+pkg-dfwnsz 9:wn in (Fig. Below). The batteries have emfr+n9f:spw f;gk3-udz s 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 resistance 66cm you rl( ) f/pp9 s:msjo3mlc91vu$r\,=\,1.0\Omega$.
$I_1$ $\approx$    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 currentx14.n akum)pb ;/ hbxxs in each resistor of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curr+800jgecqmy)xf y3xvents $I_1$,$I_2$, 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 , g*y wcjx(9 j59 :ftv2abqu/-a4qkm4yb tkg u$I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteriesu;neg tr:v xxv-d/nqjp2. x:4, with unequal emfs of 2.00 V and 3.00 V, are connected as shown in (Fig. Below). If each vxt-q .x:unj ;e42gr:d np vx/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 c jqid30-c/hfkb9 ss f3apacitance 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 (Fig. Below8 n/8 5qoptaub), calculate the voltage acrossb 8qt8n5opa /u 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 redvjqd; 5hz 6sh/grwb: 2uced from 4800 pF to 2900 vjg;6sdzrb /q2:h5 whpF.
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 accidentale1b;gaa6mij:i/ea d- ly constructed 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 in (Fig.b2, 3 gmdg*86bplafg m Below).

  In (Fig. Below), if x b/6p/.rdsgc5 +o bmg$C_1=C_2=2C_3=22.6\mu F$, 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), suppzeodc-b td 7s.e e ajf6f9 z08z-6fyb:ose $C_1=C_2=2C_3=16.0\mu F$, 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), leta p +0v6bmpdsq2*m f,y $V\,=\,78V$ 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 (F+brj;a ;gh p5b h3mu)pig. Below).;3bhmgur);b p+h ap5j
(a) Are the two capacitors formed connected in series or in parallel?
(b) Determine C as a function of $d_1$,$d_2$, and A. Assume $d_1+d_2$ is much less than the dimensions of the plates.

  A circuit contains a single 250-pF capacitor hooked across a battery. It is desi jdu,zzab-;g qk ()l3oa b:n6qred to store three times as much energy in a combination of two capacitors b6,k( z3jag:lbobu)n -zd;aqq y 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 serixa,1fbu 8 o;edes with an unknown capacitance, and as a series combination they are cobfodu 8 a;1,exnnected to a battery with an emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often connected as shown in (Fig. Below). The leads are * ,ha e5b*wxlqsaid to be capacitively coupled. A tqe wa *,hx*5blime 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 resi(17)dc m-2 nh)ze .inqewrahtstance 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. Below b) (,svct- pkvm3jezv r ,q19ig*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 arran(cwc6e;r w.os i mu;1xged as shown in (Fig. Below). Then a pomu rcx(; o.wi;6ews 1ctential 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 meter sensitivbs9 o +,;pemgopuq;nc xzj40/ity i pgm9ponb0,;zxej+/s u 4c ;oqs $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitpz 1 1w9n7arrvhg 9pd*ivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internao9, 3e9 ruy 2hsxe yu/3v(bh3yrwgwdx n3u27z l resistance of $30\Omega$ and deflects full scale for a $50-\mu A$ current. Describe how to use this galvanometer to make
(a) an ammeter to read currents up to 30 A,    $ \times10^{-5 }\;\Omega$
(b) a voltmeter to give a full-scale deflection of 250 V.    $ \times10^{6 }\;\Omega$

  A galvanometer has a sensitivity abty )bnb202s9riwg: (3ijg.0kor abof $35k\Omega/V$ 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 conswkry4 az 19)hzists 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 connectedtw1n mp1 eqg m3-se/+e 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 resist lgm21wnah-mv c+8eyo d p1p70ance 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 s1.0ivi, go vpihould the voltmeter of Example 19–15 have to be in error by less 1v ip0vo. ii,gthan 3%? $\approx$    k$\Omega$

  When the resistor R is2camlp c.2t p .en fh87*.tgin (Fig. 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 potential difference between two poinu+smz1b2zl pyqc :0y4 ts on the human body. Thezly2 :+0s 41bpqzuc ym 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 prodg/phg:d kv s3*uce 50 W, 100 W, or 150 W, at 120 V. Such a bulb conta ghg3:v */psdkins two 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 outlet. Ea6tcwz 7w3jfs 1wr i ;+m+uln9lch of the wires connecting your apparatus to the 120-V source has a resis;siun+37tj w1zlf9 rwlm w6+ ctance 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 patientbvl5w9(1q:fg0.qu fw f8dbn bs who are connected t vqq9b lfu. 8wgnb(0:5wf 1fbdo 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 apparatus. This is shown schematically in Fig. 19–60. Calculate the current through the patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must a 45-b z,v cene/28xeos:s 9V 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 designeo4o tt:)7+*lpzuh)l k hnz+ozd to operate at 72 beats/min using a $7.5-\mu F$ capacitor in a simple RC circuit. What value of resistance should be used if the pacemaker is to fire (capacitor discharge) when the voltage reaches 63% of maximum?    $ \times10^{-5 }\;\Omega$

  Suppose that a person’s boc)8hb4tn9 yas dy 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 a type of “bridge circuit” used to make measuremeni2wf21dxo,eka- lc 9wts of resistance. The unknown resistanw9oaixwf 2l- dec k2,1ce 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 unknos wgpxkxap + b:h-;86cwn resistance in a Wheats6kgpab : xxc;h -8+spwtone bridge (see Problem 71;Fig. Below). Arms 1 and 2 have resistance of $38.0\Omega$ and $46.0\Omega$ respectively. Balance is achieved when $R_3$ is $3.48\Omega$ How long is the platinum wire?    m

What are the values of effective capacitance which can be obtagac)z,dof6c e0uw:w,awcldue1ne17 oz 8 2 .m ined by connecting four identical capacitors, each having a capacitafd1g7ue z .,2l ccnoameo6dz1,uw we: wca0 )8nce C?

  The variable capacitance of an oll ,j.ce)mr69r*qx .ysifb y(f:ly)9f+tb ifu d radio tuner consists of four plates connected together placed alter)eiu.9)fyby6 q my .frtc+*j,(lbi9f flsrx :nately 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 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 emjvjw+i f4 -:vad5 :dis drawn from it and 47.3 V when 2.20 A is drawn. What are the5:+4 dmvj :ijwe- vafd 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 qtm*/ b:5mtcythe $4.0-k\Omega$ 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 paralle;r2jk3oob; ;ne p)zlbl-plate capacitor has capacitance $C_0$. If two identically sized dielectric slabs of dielectric constants $K_1$ and $K_2$ are inserted as shown in Fig. 19–64, what is the new capacitance? [Hint: treat this as two capacitors in combination.]

  For the circuit shown in(Fig. Below), n-3fu l or c)9x7zj eaf51p0uwdetermine
(a) the current through the 14-V battery $I_1$   $ \times10^{-5 }\;A$ ----待选择----downupward 
(b) the potential difference between points a and b, $V_a-V_b$.    V

  A solar cell, 3.0 cm square, has an output of 350 mA at 0.80 V whk.ugrv1 zjsevlz9tiw)(88 l ; ba5y +ien exposed to full sunlit a5l9(yvk; v ewi18i+.u sb)gzlj8rzght. 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 voltribw6t6- vbn/ 7eqt9gage 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 neoy.5( bvxx+7et gm m.(-nrs wwsn-filled tube as in (Fig. Below b). This neon lamp has a +gyv s-bst(. w(nxmwr e.x7 m5threshold 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 0/o6yb : 1rzad7c nmax$20-\Omega$ 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 u ;-3j1pb;qwlgn5 ao:ca sa8j in (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 resistance of the ci c a6df)g gx *3zhyr-/.g(blqfrcuit 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 shown i; wo1:-tvkbmh (i6(y9hrrol f n (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeter reading, the value of R wilv 6m-wo9 :l1rfr (itbkhy(ho;l 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 p- 4h nf9yblycvs/,c a ;70ruvat 2.5 W and 3.0 V is operated by a 9.0-V battery. To light the bulb at its rated voltage and power 97ay4;sc c-rvl/f ,v 0bpyhun, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$