Explain why birds can sit on power lines safely, whereas leaning a metal-cf, l c-vfo2z ladder upczf,vf-2 loc- against a power line to fetch a stuck kite is extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree lights con)7vf ccd plrtf4 8h:d.vwu :m5nected in parallel versus those connected in m4.uw rp: hdct7 vld)f c5:8vfseries.

If all you have is a 120-V line, would it be possible to light severaa/pdqje.n6(su1xs -wa:(6g bo5 ue h wl 6-V lamps withoute6u((-w qh:gs5 1.d/aoe6jsxwa u bp n burning them out? How?

Two lightbulbs of resistance f4y* vy* p i0mue2un2a$R_1$ 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 zr wbcdg18jiwik 0k 4u)p4bf+v1i.b6in series or parallel? How do you 1bb 468z1vkwrip f. +kjuigi)bd0w4cknow?

With two identical lightbih: b(:fyi na*ulbs and two identical batteries, how would you arrange the bulbs and batteries in a ch a(fy:b :*iniircuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected in series8z3v4buua sna9 cu i4s;g/:)nkdek,h to a battery, does the battery have to supply more power or less power than when only one of the resisb)ze kd a;/ na9 ,k hug4sscniu84v3u:tors is connected? Explain.

You have a single 60-W bulb on in your room. How does the overall rezcqpq )t ;.ix0sistance of yx c;p) tqi.q0zour room’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 (or d* )a- gizv1bkp7zk uokex;9 e(irection) of a battery’s emf depend on t ae9( )bp1k-7* ;ozvix ugezkkhe direction of current through the battery? What about the terminal voltage?

  Given the circuit shob8nm q a15sr(c9u vk.awn in Fig. 19–36, use the words “increases,” “decreases,” or “stays the same” to complete the follb1 5(kr cns.amvqu9 8aowing 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 connecz,yt/gv8j* o nted in series? For what use are they connected inv,8*j zy ngt/o parallel? Does it matter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever exceed its emf? Explf,*m,;l9m zmh arxck0ain.

Explain in detail how 1ck0/ u i wvom7aciy:4you could measure the internal resistance of a battery.

Compare and discuss the formulas for resida(l,g 94va/cl iojx4stors and for capacitors when connected in seg v/i,4la4cdaj lo(x9ries and in parallel.

Suppose that three identical capacitors are connyc+hp - j2j3io:sue+l ected to a battery. Will they store more energy if connectedu3jjh-c2e :oi+ sy+l p in series or in parallel?

Why is it more dangerous to turn on anh w24j7pggaphjqv9+yf * ,dx 4 electric appliance when you are standing outside in barh,+2p q japh jy74v9gx gfd4w*e feet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphhr*)67 nv(dee fa( ne4m3wprz one. The changing air pressure in a sound wave causes one plate of the capacitor C to move back and forth. E anh*(d 4rwr7vp( znmee) 36efxplain 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 inc hd l.xy:gl07tn+ ao9p vtn bhzy rx*:-jg*1- (Fig. Below) can be used to opec:-7t.hon xn+lrj:vby1p y xdg tg-0*al*h9zrate the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from the battery until the capacitor is vpnc q q*hq2;66nc u9bcompletely charged. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If not, where does the extra ener; *qnq6ch29q vnb6 pcugy go?

What is the main differencu t8h(hil9pdj9g (kb6n( ng d7e between an analog voltmeter and an analog ammeter?

What would happen if you mistakenly used an e y,y-g n x ptby 78mwi,l9w/obv/0s0tammeter where you needed to use a vo tv8tw0 9o,m i/bgnx/lew-7p s0yyy,bltmeter?

Explain why an ideal ammeter would have , s3d9ulsilk *5 eh+q ls/3ltrzero resistance and an ideal voltmeter infinite resistancel k/se3l s dl3 t,9r+hlqs*5ui.

A voltmeter connected across a resistor always reads less than 5vdq6tdc62 2 0wqk dc)z c6qocthe actual voltage across the resistor when the meter is not present.od5c q )cvc02qwd d qtz266ck6 Explain.

A small battery-operated flashliux9p;+ wznc(9m6ko q-myhw4 kght requires a single 1.5-V battery. The bulb is barely glowing, but when you take the battery out and check it with a vol k9; -w(4zny +m69hckq owupxmtmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltaq/+ dby5t oz5rp*i8wum osx2.ge 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 r la6fd293lg t pnzb-s4vd ;1usesistance 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 hav,pbumj( syfwn +)6i 3he 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 havg4/t-pjiu-y 1xr z(fn+ zyq h(e a $6.0-V$ battery and you wish to apply a voltage of only $4.0\,V$. Given an unlimited supply of $1.0-\Omega$ resistors, how could you connect them so as to make a “voltage divider” that produces a $4.0-V$ output for a $6.0-V$ input?

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

  A battery with an emf o m cb k+4fj52n9.boju;bzymg ,f $12.0\,V$ 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 arfm4 art81cwdz0s :p;n 8xp- ve43 oqsbe 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 pa*8(l 8cf7z/ x ez1fxoyid9o6ah-guedrallel 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 o 7fpuqg 0jk))rj.l o1nf an electric 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 sh7fjcet6 ,oct- n7rab) own in (Fig. Below). Answer qualitatively: fott b,j-r77c)anc6e
(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 ofg x rc8)g/4m6b6ggy9r(debp)vulkw2 the circuit connected to the battery in (Fig. Below)? Eau b6pd(8gw gkgy4rc9)lr)/g6x vb2emch resistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown in (Fig. Bc6m8kz/iut mh * 4j1lvelow). Qu /k ulv6mh*cmjit8z 41alitatively, 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 5a.0elpl+ 5j,ncdh zq(Fig. Below) and show that the sum of all the voltage chaqj l.+05 ndzech5apl ,nges 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 bag+1zi : n/6eivr1s frmttery    V 12V battery    V

  (a) What is the potential difference between points a and d in (Fig. Beloweo1l5 h6nciiq-4r*bp a) (same circuo c6p-41bh*qre l5iin it as Fig. Below b, ), $V_{ad}$    V
(b) what is the terminal voltage of each battery?
80V battery    V
45V battery    V

a
b

  For the circuit shown in (Fig. Below), find the p4-8l.;mg :g4rff iunkmzor8 4vpafx7otential difference between points a and b. Each resistonm- lg:zvar8 8.g4ixffmopf7rk44 u; r has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions ozdr1r g/d:c. zf 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 each battery has an aag59ylk eyi02da 3wa:vt-p0internal 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 direction v76pl 9eqdm1ns of the currents in each resistor shown in (Fig. Below). The batteries havpnve q 1dl796me 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, assumi dnb+z- + lyct(gmq26hng each battery 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.ssi y 0;.qtw-c 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curryx dq9br94pl:ents $I_1$,$I_2$, 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 curren (aw*,6qh z0ab0my+drm v 2cxpt $I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, with un ji /;rtv6qs+;)thye hequal emfs of 2.00 V and 3.00 V, are connected as shown in (Fig. Below). If each internal resistanj;)ir;6+vtythsq e/hce 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,.0q7lj6yf3 7qgd ekkv 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 ofkkt3eseg n3 boxql 215p+6 e8u (Fig. Below), calculate the vol2kxgq e3et51e+s no6bl3u 8pktage across each capacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of l9q lxx+ rfyg:*-qo-sa circuit is to be reduced from 4800 pF to 2900 pFqs-+fq r* -9:o yglxlx.
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 construyw 2sy6gmse77cted 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 capa s blpqxmqq x+(.hvx rhp41*(;citance of the circuit shown in (Fig. Below).

  In (Fig. Below), if g)79xcf );jv4z o dybg7+ pvia$C_1=C_2=2C_3=22.6\mu F$, 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 9;mykxd)cb+ x$C_1=C_2=2C_3=16.0\mu F$, 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 jzm+ f, f uq(gbcw(qlf0+nm:)$V\,=\,78V$ 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 (Fig. Bz *r v t)6 yufdppse /.y(jv8n0vi8ss-elow). (8e *s /-p vsp.6y 0if)vu8vjstrdyzn
(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 desxoi)6 bc4 sll2+ sg t:+wabzjx989ywnired to store three times as much energy in a combination of twbgl:zwn9w ya4ix o)9+c bsj+ l682xst o capacitors by adding a single capacitor to this one.
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is connected in series with an unknown capacita hnwbp8i 72nbo*us3 7qnce, and as a series combination they are connected to a battery 87hbi7p*u2nqsw bn 3 owith 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 ce 51 (8 zlvkmij 2p7tyjgyr*;vgwp4-+xjx gl3 onnected as shown in (Fig. Below). The leads are said to be capacitively coupled. A time constant of 3.0 s is tyjg4 lr(xl3;*p51 wvk 2pi- 78zmtgv yxjg+eyjpical 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 resistance is s-qf: *y;cnt kwt 97s k)z7 riwdek)aq.6b; vl$15.0k\Omega$, 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 zjg1 vxd:/kv7low 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 arranged as shown in (Fig. Bejgbrauix 4tn:(,i.sq) k:e 4tlow). Then a potential difference of 24 V is applied as4.nru i):q ig xtbjt(4ak,e: cross 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/ikxzxrl(9x i0e ;k)b a voltmeter on the 250-V scale if the meter sensitivit( ;kx/9e)kbxliz0i xry is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivity oh 0l 5ug5rdpz29l8zthf $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an interhqu 1pj/7fsv.h /qw 8r;* 8 vl.gnsnbcnal 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 of j 2yi97tbfebs v3q(2 t$35k\Omega/V$ 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 consists of a c(1f8 4+ sak tnml-9q6dzazlm$0.20-\Omega$ 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 vhgyx6zqo)w4. )r)e wconnected 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 internab.u(sh9 qbh+( vn r.)icpdw ,bl 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 voltmeter of Example 19–15 have to be in errtw74ik-* xcznql 3q5aor by lesn-53qc4zl iatw k7q x*s than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) is hps3ey ;/di1,0bl yzyi *nbm3 $35\Omega$, 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 0graw 8o6y*z/ph+ hec2rl v1p0.25-V potential difference between two points on the human body. The resistance is abou6p1grw h +er * 820vzylh/apoct $2000\Omega$, 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: 8cfp1;g s tjr/;ipxwontains two filaments that can be connectew pitx/jf 8pc;; s:1grd 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 as:,a -yp-a mdhpparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 120- yd, maap-:hs-V source has a resistance per unit length of $0.0065\Omega/m$. If your apparatus draws 3.0 A, what will be the voltage drop across the connecting wires and what voltage will be applied to your apparatus?
$V_{wires}$    V
the voltage applied to the apparatus is $\approx$    V(Round to the nearest integer)

  Electricity can be a hazard in hospitals, particularly to patients w u;+j iw m-2nm:7whf/9i lu3z-w kyuvrho are connected t2 -um9u yf w7/w zuw:m lh-+knr3;ivijo 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-V battery exp2z1u f*keecia0vu z .+end to charge a $0.40-\mu F$ and a $0.60-\mu F$ capacitor fully when they are placed
(a) in parallel,    $ \times10^{-3 }\;J$
(b) in series?    $ \times10^{-4 }\;J$
(c) How much charge flowed from the battery in each case?
$Q_a$    $\mu C$
$Q_b$ $\approx$    $\mu C$(Round to the nearest integer)

  A heart pacemaker is designed to operate at 72 beats/min usinghe-7 8;1rlinejhh3( ,+auuos hp*g mp 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.s +w8sfr24 :hwhf+b zambf u) 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 /oo(tooa(tcus/*f.5e. bdbk make measurements of resistance. The unknown r t/osa.oc( oedft(kuob5/b*.esistance 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 diaug b(7k xpob,m) kt.eru h85*emeter is placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Armso)re5bbe 8*hu g.u( 7mpkx, tk 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 -j)sv4/;qv-fzynh v zbe obtained by connecting four identical capacitors, each havifn;-y v-vh/z4zq vs) jng a capacitance C?

  The variable capacitance of an old radio tuner consid,az t6z01dif*z p7p s; jyn 79pvz8jdsts of four plates connected together placed alternately between four other plates, also connected together (Fig. Below). Each plate is separated from its ne7ptdfy 6d19*7j;zzd 0spzp8 nijv za,ighbor 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 is drawn from ejo 0un3pj/j* ):;old1trlrhtt +q3uk-ja ,wit and 47.3 V when 2.20 A is drawn. What are the emf and internal resistance of the bat;j:+t,jpro jn ldt1uq-0oklr/ja* h uw 3)3ettery?
r    $\Omega$
$\varepsilon$    V

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

  The current through the*d xa,o*v2p6x tilis 8 $4.0-k\Omega$ 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 capjkm9zkb3r p)3acitor 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), diq)a 2;yovjxqq s4urz6(g8m ,etermine
(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 0.8vuqsw p;zz)5l,+;is w0 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 is needeq5lsz +,isvu pw;) z;wd.
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 fixd09zc7xg.sfznqkc3 . d15jg at 6f o/red output 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 neon-filled tube as in (Fw0 l1yrtwdd4 ,8je/an ig. Below b). This neon lamp has a threshold vo1 nwreat/ ddw,j4 8yl0ltage $V_0$ 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 thezwvc sv qr./ft419ak1dy10p1 dbgv -m $20-\Omega$ 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. Bels0.33dwlvj 2l ilbc 7;brt+onow), 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 th w 0yajp82vo)we 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 7q3d8azlyv; lht 1p x*an ammeter can be connected as shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeteav 71 dh38*lqy;t pzxlr 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 ra7c*mbi9f8jg t t x*n t)0ax,aeted at 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, a resistor R is connected)0cx nb jx*,t itg9efm8ta a*7 in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$