Explain why birds can sit on power lines safely2 10)(md4u fqu hluvkv, whereas leaning a metal ladder up against a power line to fetch a stuckfdq4klh)102vv m u(uu kite is extremely dangerous.

Discuss the advantages and disadvanz)sl)l.bhh+ i+z d(d gtages of Christmas tree lights connected in paralg)ddz s+ l)l( ibhh+z.lel versus those connected in series.

If all you have is a 120-V line, would it be possible to light d1 jv(;ajr .js.ina8(*8dheha+vw asseveral 6-V lamps without burning them wjvj.is rdh;h e j(sa(8a.d8v*a1+ an out? How?

Two lightbulbs of res(xxk 1ccm7h8vxdg+z0gc: wv; istance $R_1$ and $R_2(R_2>R_1)$ are connected in series. Which is brighter? What if they are connected in parallel? Explain.

Household outlets are often double outlets. Are these connected in series or pagpg d; ,qyn(0b (0txcvht g5q*rallel? How do you kn vgq p;q,gxch (g0t 0y*btnd5(ow?

With two identical lightbulbs and two identical batte q +0ihs42sfvhries, how would you arrange the bulbs and batteries in a cif+hv24is qsh0rcuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connectedn5k0eykh 3rpadk6(j2 in series to a battery, does the battery have to supply more power or less power than when only one oj3kr( ekh62y5dnk0apf the resistors is connected? Explain.

You have a single 60-W bulb on int(uar1sp; w )+ y/yeyj9s p:.bd cueb1 your room. How does the overall resistance of your room’s electric circuit change when you turn on an additional 100-W11.ep jy 9ctas+p) ;b:uryb(usw ey/d bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below) qb bqq4tyv uf95) j:kzl,6em 04jq/wr, does the sign (or direction) of a battery’s emf depend on the direction o e l64jv9qur,tq0jy)/ bbw5:kq4zfqm f current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the wordsfrps-k1 5bkj , “increases,” “decreases,” o jrp,bf-kk5 s1r “stays 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 j; yblrh1tr3,what use are they connected in parallel? Does it matter if the batteries are nearly id 1th rbyrl;,3jentical or not in either case?

Can the terminal voltage of z )isqst+ub7; a battery ever exceed its emf? Explain.

Explain in detail how you cout( y j0ufwh;s/kp5 /5nlmfcr (b ;gtu/ld measure the internal resistance of a battery.

Compare and discuss the formulas for xqukjl0)kdr vum 2n:/iy 9*; rresistors and for capacitors when connected in series an:r;kr)y9v l0knuiux q*2jd/md in parallel.

Suppose that three identical capacitors are connected to a battery. Will they vg1i, if zok/.store more energ/k o i,1igf.vzy if connected in series or in parallel?

Why is it more dangerous to turn on an electric ap)z8w xl2 ktlh(m99zm *yubd /kpliance when you are standing outside in bare feet than when you are inum*dy/ bzwkz(t )hm92lk9lx 8side wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or a(pgks9z(mv0 condenser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to move back and forth. Explasgaz((mkvp 9 0in how a current of the same frequency as the sound wave is produced.

Design a circuit in which two diffeb g:7*6tr phwhrent switches of the type shown in (Fig. Below) can be used to operate the same p6t7:hrbwg*h lightbulb from opposite sides of a room.

In an RC circuit, current flows from the battery 6.; 0(5cv.cax u o*xywideriw until the capacitor is completely charged. Is the total energy supplied by the battery equal to the total energy stored b.6ruoidca5 0yv;.w(wixe c*xy the capacitor? If not, where does the extra energy go?

What is the main difference between an analog voltmeter and an analog amiekg+ q y:u;0 h;:eajumeter?

What would happen if you mistakenly used an ammeter where you neex 7ree hm*a:w8ded to use a voltmee8*: em r7xawhter?

Explain why an ideal ammeter would hav kg 0e.dqy;y;oe zero resistance and an ideal voltmeter infinite resistanced0gy okq;. y;e.

A voltmeter connected across a resistor alwaysw new27tlp4; f-) qine reads less than the actual voltage across the resistor when the meter is not presf wl4;)-ptqwei72en nent. Explain.

A small battery-operated flashlight re/s(), qwfmnohpj 8e1g(qrl)iquires a single 1.5-V battery. The bulb is barely glowing, but when you take the battery out g,sn ife))qw jlrhoq(m / (1p8and check it with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminn qye9l( 51-ay*adcptyfx4 *k g4 )twtal voltage for a 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 ra3 rdfi,5wu-y) *jlhc esistance 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 camkqs -ed 0lrz+jh6om;tl,dy 52.:y 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 wa6vc.xtz*ugpo 7 2 w0h 3ux2ia $6.0-V$ 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 2m*r tr4l,:tcr*v lb hof $12.0\,V$ shows a terminal voltage of $11.8\,V$ when operating in a circuit with two lightbulbs rated at $3.0\,W$ (at $12.0\,V$) which are connected in parallel. What is the battery’s internal resistance?    $\Omega$

  Eight identical lights are connected in series au.y.39 / ijkynffbe1z /nd;p qcross 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 conne5nsco04a q 5mccted 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 circuit reveals tha g xf.0)w -yvzmhoy)5it 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 6+xxqwc5s;vdq 0iz1ufc m1w4 resistors shown in (Fig. Below). Answer qualitatively: q;vq51 xcdci +f 1 mzwus4w60x
(a) What happens to the voltage across each resistor when the switch S is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(b) What happens to the current through each when the switch is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(c) What happens to the power output of the battery when the switch is closed?  ----待选择----increasedecrease 
(d) Let $R_1=R_2=R_3=R_4=125\Omega$ and $V\,=\,22.0\,V$. Determine the current through each resistor before and after closing the switch. Are your qualitative predictions confirmed? Notice that the current through each of the parallel resistors is half of the total current, within the limits of significant figures. $I_1$    A $I_3$    A $I_4$    A Notice that the current through each of the parallel resistors is one third of the total current, within the limits of significant figures.$I_1$    A $I_2$    A $I_3$    A $I_4$    A  ----待选择----YesNo 

  What is the net resistance of the circuit connected to th xflfcc 80kab yz,8-um1rkqfxi-/g11e battery in (Fig. Below)? Each resi/m-fxfu,q1 0 czfik yl g-a8kc1r81bxstance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) arezfkju: 1kim8nl50; hv connected to a battery as shown in (Fig. Below). Qualitatively, what 5ki1k8hj;0l n :ufzvm 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 6vhifi .c;wtb+)+ tmaof (Fig. Below) and show that the sum of all the6c+iit.w)tm ab fv ;h+ voltage changes around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each batteryy( gr6o3r y)t wgbx,41)ojohf in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential difference between points a and d ih dq8tgs p66 bbkuun 6 u/wksg0)6:ax9n (Fig. Below a) (same circuit as uab6 0)pux9hbs6 t6 ggqwkdunks6/:8Fig. 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), 9kkk8g j 06h vcy)mr.pfind the potential difference between points a and b. Each resistorkh y) j8m.cpk90rgvk6 has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitu nfx+ki 73oc1 11h4-pgclilxq des and directions of the currents through $R_1$ and $R_2$ in (Fig. Below). $I_1$    A  ----待选择----leftright  $I_2$    A  ----待选择----leftright 

  Repeat Problem 27, now assuming that yf gqyhu8 bh78 t(:o*ar.uk1keach 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 a 28-ac9 sl zb-02weapubi6dy mnd directions of the currents in each resistor shown in (Fig. Below). The batterieswbubsa-l6 aiy0 -c8 2pdem9 z2 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 battetteu.0hr08/giav f h2ry has internal resistance $r\,=\,1.0\Omega$.
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Calculate the currents in each resistor of Fig. 19–49. 6lfyv lg0h: qkj3 +h26yis3w l
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curzb4lbtxu 2;..yvbs1dg..b 0fgxe p0zrents $I_1$,$I_2$, 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 currenyvaow) 1y) yx+t* d-elt $I_1$ 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 2.00.5.h byn *hnxy V and 3.00 V, are connected as shown in (Fig. Below). If each internal res5.ynhn*yhx . bistance 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 3200 pF, 7500 pF, ano4.l q,pw w opbz;.brdf74*mbd $0.0100\mu F$ . 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 networczo;4r 0s(-hm:a cpp ak of (Fig. Below), calculate the voltage across each capac4zspo cmhra(- ap:c;0itor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of a circuit is to be reduced from 4800 pF lggehq5,p0b/ to 2900 pF,hplqge0b/5g .
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 wm+ :m c1razo-i )twt2las accidentally 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 capacitazju y+i1jmvu6. /)xeve*sg :ince of the circuit shown in (Fig. Below).

  In (Fig. Below), if sy *)s81cbd-tqa u tm*$C_1=C_2=2C_3=22.6\mu F$, 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), suppose --t ;aa:mj0h0zseeufk *- oju $C_1=C_2=2C_3=16.0\mu F$, If the charge on $C_2$ is $Q_2\,=\,24.0\,\mu C$, determine the charge on each of the other capacitors, the voltage across each capacitor, and the voltage V across the entire combination.
$ Q_{1}$ =    $\mu C$, $V_{1}$=   V
$ Q_{2}$ =    $\mu C$, $ V_{2}$=    V
$ Q_{3}$ =   $\mu C$, $ V_{3}$=    V
V=    V

  In (Fig. Below), let t3rss7r22xgl h s zjb:245zhl$V\,=\,78V$ 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 /(bjh2*j/ s1e mqpd5cgc rnw* shown in (Fig. Below). mbpn*c25w q*(ej/h rdc/js1g
(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 i,wz;; n7xsq7 l ezrx9hooked across a battery. It is desired to store three times as much energy in a combination of t9 xxsiq7z,ne7r;wl ;z wo 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 co bu 9okzv-z646vlx-we8 /wsprnnected in series with an unknown capacitance, and as a series combination they a64 ux89l vzbek6ws/zvrop-w- re connected to a battery with an emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often connected as shown in (Fig. Below). The leads ae,*3ek z,t5rzpdc :hi re said to be capacitively coupled. A time constant of 3.0 s is typical and allows rapid changee ,5zik c3:deh ,*trzps 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. Beloh3*n t+gl: *vk rr6rm h4ybs2ow b), the total resistance is $15.0k\Omega$, and the battery’s emf is 24.0 V. If the time constant is measured to be $35.0\mu s$, calculate
(a) the total capacitance of the circuit    $ \times10^{-9 }\;F$
(b) the time it takes for the voltage across the resistor to reach 16.0 V after the switch is closed.    $ \times10^{-5 }\;s$

a
b

  The RC circuit of Fig. Below a (same as Fig. Below b) haxy r* ql7ts5x*s $R\,=\,6.7k\Omega$ 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 arranged byg )rir 7ms,/+grf2rog(g0 sas shown in (Fig. Below). Then a potential difference of 24 V is applied across the combinatyrgsi,r bgmogr(g2 )/+07 fsrion 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 25akue2*n,,3ta ;nn vhc0-V scale if the meter sensitivity i, u2 h,;nnc*aakv3nte s $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensijdte(m :n1) tft-g0xb tivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has azdee74qvf8.b g+g +tfn internal resistance of $30\Omega$ and deflects full scale for a $50-\mu A$ current. Describe how to use this galvanometer to make
(a) an ammeter to read currents up to 30 A,    $ \times10^{-5 }\;\Omega$
(b) a voltmeter to give a full-scale deflection of 250 V.    $ \times10^{6 }\;\Omega$

  A galvanometer has a senss6k g0j.kao;bey :+i;kf.4 gfr m2d myitivity 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 con*p: )uto5mca gsists 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 connected to a4dkn 78x.uq9b( mmu e+xr+y fo $R_1$=$38-k\Omega$ 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 isg 4(-yep;xf jm $63\Omega$ 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 volt+u(8;i:gf05phxbl h i rzfkj 6meter of Example 19–15 have to be in error by less than 3%(gxikphz0+ij h: r6b8 ;fflu5? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below5bb g4k 2tnbmih+k)7h) 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 bzy 2rrsc90 rfr25g/di etween two points on the human body. The resistance is about 2ri r/gcs2d y05r 9rzf$2000\Omega$, 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 102nnckhqroq l ,u-6 .t50 W, at 120 V. Such a bulb contains two fitonq-qh62ln , kc.0urlaments 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 electrica0(s.m vom(cw outlet. Each of the wires connsm0w v(amo(c.ecting your apparatus 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 patie 4avz7 nu jmij92:lke(xtp x/5nts 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 apparatus. This is shown schematically in Fig. 19–60. Calcula 2atk(x pj:m/7 zv5in9 4ljexute the current through the patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must a 45-V batteoi3r tz ;3s-awry 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 d p9mt36r ,z1 0e/nw7zptunnspesigned 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 body resistb:bqj9b9mj5d l5ghv .ance 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 6coi/.:a rreif w/ pu-“bridge circuit” used to make measurements of resiwre p. :fiio/ac- /ru6stance. The unknown resistance to be measured, $R_x$, is placed in the circuit with accurately known resistances $R_1$ ,$R_2$, and $R_3$(Fig. Below). One of these, $R_3$, is a variable resistor which is adjusted so that when the switch is closed momentarily, the ammeter Ann Meter shows zero current flow.
(a) Determine $R_x$ in terms of $R_1$ ,$R_2$, and $R_3$.
(b) If a Wheatstone bridge is “balanced” when $R_1\,=\,630\Omega$,$R_2\,=\,972\Omega$, and $R_3\,=\,42.6\Omega$, what is the value of the unknown resistance?    $\Omega$

  An unknown length of platinum wireb0mt8c8f i s4x 0.920 mm in diameter is placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fi8i 48xb fs0cmtg. 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 obtainar ,pl do8k,dxyv(40jed by connecting four identical capovxa 8 prd ,k,l40jdy(acitors, each having a capacitance C?

  The variable capacitance of an old radio4ftkzw8dc8 x jhb 17,l tuner consists of four plates connected together placed alternately between four other plates, also connected togetherj8b z4f 8td7h1wx,clk (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 4 . o /.-iqggm5xcv-w*di iw6ve0.8 V when 7.40 A is drawn from it and 47.3 V when 2.20 A is drawn. What are the emf and internal rwm-gic ox -gewd.*i vq/5.vi6 esistance 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 th. obsrg:di 6i d;v8:lne $4.0-k\Omega$ 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 capacitorilqh 0 0(/t)mgvtl8 9,ehpaux 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 (cq zj,lsd b o:+f3h;oin(Fig. Below), 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 /g-lrs:o+ca+t.m hlv output of 350 mA at 0.80 V when exposed to full sunlight. A sol.h/ml vos:r -tac+g+lar 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 12.0ou p0hbvxhwz 9 j/8(j. 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 neon-filled tube as isif7t(h,sjvp7/ hvj8 n (Fig. Below b). This neon lamp has a threshold v(vfp 8s7h th,/vis7jjoltage $V_0$ 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 thj(d:hmro4 u/n3e)p xc e $20-\Omega$ resistor in (Fig. Below) does not change whether the two switches $S_1$ and $S_2$ are both open or both closed. Use this clue to determine the value of the unknown resistance R.    $\Omega$

  In the circuit shown in (Fig. Below), the xl 34,2ggjz/b org ak*$33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalentm o cdai c5226wuqhn-) resistance of the circuit shown in (Fig. Below)? $R_{eq}$ $\approx$    $\Omega$(retain one decimal places)
(b) What is the current in the $18-\Omega$ resistor?    A
(c) What is the current in the $12-\Omega$ resistor?    A
(d) What is the power dissipation in the $4.5-\Omega$ resistor?   W

(a) A voltmeter and an ammeter can be connected as)0 7 :ains7e2uh(vld zo2xma1h6s ofyr p*m4p shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeterh d7:li4a)hz2 uo0veyss7ox( 26prpnm a*fm1 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 operated by a 9.0-V tagju5 4ac* ;ibattery. To light the bulb at its rated voltage and power, a resistor R i5 uijct;*4aga s connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$