Explain why birds can sit on power lidw.,j jqet/d a e.,gd7nes safely, whereas leaning a metal ladder up against a power line to fetch a stuck kiewdq7a t /,.de .jdgj,te is extremely dangerous.

Discuss the advantages and disadvantagesgqbd tlf7/40s of Christmas tree lights connected in parallel versus those7ds 0f/btl qg4 connected in series.

If all you have is a 120-V line, would it be possible to light several 6-V lamps:g7p j p4syx65x*rkuz without burning thkurz p6*jp457gxsx:y em out? How?

Two lightbulbs of resistancet 0jwqi5kiu,* $R_1$ 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 th*zsosaz2i: m 2ese connected in series or parallel? Howm sazz*i:o22 s do you know?

With two identical lightbulbs an1i64.pxdpfo6 ue d,*tcp kwc)hzd-r 0d two identical batteries, how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligible iniepp6-c.4 xr0 f61h,kcdod w )ztpd* uternal resistance.)

If two identical resistors are connected in series to a batt ti fn4rfhsc64lh;/0oery, does the battery have to supply more power or less power ;4hs ofh fc/ irnlt064than when only one of the resistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the overall resistance of se 6fd7 b/jv7gpf3 q+ryour room’s p73/qg6fv 7fbr+e d sjelectric circuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (suv6 0 7v-e54topivunedpd9s9cch as in Fig. Below), does the sign (or direction) of 56icv9use-eto490d7 p pn vvda battery’s emf depend on the direction of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–3ex*h 9;o m-qe0jd1hmi +fo. ve6, use the words “increases,” “decreases,” or “stays the same” to complete the foll v-q9 .iojhd o+efx0mme1*eh;owing 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 batterw1eabo mmr:y:0oacg +,ef)7hies connected in series? For what use are they connected in parallel? Does it matter if the batteries are nearly identical or not in eio7oeh1b,+mm 0:yarcwg : efa) ther case?

Can the terminal voltage of a battery ever exceed its emf? Euvj3jcym82.iu6 ps -lxplain.

Explain in detail how you could measure the internalpunp m20 cirjee 0c).5 resistance of a battery.

Compare and discuss the formulas for resistors anfjfb )i;. +a8fdre2uk d for capacitors when connected in se f +8)adjr; f2.febikuries and in parallel.

Suppose that three identical capacitors are connected to a batterp g mop3;j5z 0(.snqcfy. Will they store more energy o ;p0(ms n fcpg5jzq3.if connected in series or in parallel?

Why is it more dangerous to turn on an e vmdr0fd a :jbck *deqt+*9g) a5i0-mflectric appliance when you are standing outside in bare feet than whjivg95d+*0* rkqbtm)d d: fc fe0a -amen you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (ok; z0t6lz1.3 q0vszef*pkosc r condenser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to movek 3p ;6 zzlqf.vsk0t*ce10osz back and forth. Explain how a current of the same frequency as the sound wave is produced.

Design a circuit in which two different switches of the type shcmjmzmg 19 2*hs/kx5kown in (Fig. Belom 1m2hszk*jgc9 x5/kmw) can be used to operate the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from the biu 1 79;vd thc0d6(0ngevdk obattery until the capacitor is completely charged. Is the total energy supplied by the battery equal to the total energy stored by(id vod1060ct ubk7 vnd;ehg9 the capacitor? If not, where does the extra energy go?

What is the main difference between an analog voltmeter and an analog2z(0mqx8q ri0dy xi,vd dw)*y ammeter?

What would happen if yo(a4yjmn g,23 hju (t 92jbdkueu mistakenly used an ammeter where you needed to use a volmn 2gd ,uyj((j9j32 tbheauk4tmeter?

Explain why an ideal ammeter would have zero resistance and an ideal voltmeteruhvf0*ue,* im infinite resista*,e*hmf ivuu0nce.

A voltmeter connected across a resistor always reads less than the k 3pt2qyew0(v actual voltage across the resistor when the meter is not 0wyt qp(ev2 3kpresent. Explain.

A small battery-operated +0xn6rs 5 b5dwbuwa p8flashlight requires a single 1.5-V battery. The bulb is barely glowing, but when you take the battery out and check it with a voltmeter, it regist nsdwu 0 rp+w6b5x85baers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an internal resf-mpdks1i 37s1fe 2t yistance 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 resistance of (krwgh7: 4ee. 1kcqmq 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 havwznm(xl )r1/wad;4x kf +v/sf e 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 hav lt0b;2q5k(pfq0 *c.v p jmwjve 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 ofk7ghxk( 7f(qth+z3f6l5 uxnf $12.0\,V$ 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 acrn6: g+z-1du*7rg;:tancofn5cq upfzoss 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 parall tl/8i)83ovmpcsehqc 6.vrj,b*n mm 4el 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 (mdce nwxm 3xf x.26mnd);3tkan 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 shown in (Fig. e6lz o .ak3, nrp ptg84.q*hehBelow). Answer qualitatively: lq*npge,k ae .t3r.h4ozp86h
(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 conne+7y+ly+t o o mvsn0.zp2uft: 7y ss0njcted to the battery in (Fig. Below)? Eacns +p7 osf :.jy7n2+y+tylov00zumst h 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. Below). Q)o+dbuh4xdcmla6.; k ualitatively,ou4lxdd+b; .akh6 c)m 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 ozdo o8t(bx spxd*/d0(f (Fig. Below) and show that the sum of all the voltage changes around the circu /*8xbx(dzt0od( o dpsit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each battera)a)p gc bfa3 hwmk)13y in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential difference between points a and d in (Fig. Beloo 8+rni1 59w *hivmtmgw a) (same circuit 5ir9mvi g 1tonwmh*8+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 potential difference betwewdy:3mg:-e rden points ar3- ywd:: gemd and b. Each resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the currene /mr5kalw styue6 x(. 3,+ouits 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, nowyfgdjb.9e e5 ab*q9q) 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 8/mw7. -x.d,)gagjz q fixlr bin each resistor shown in (Fig. Below). The batteries hj/g x-8arfd gb.,q7zli. wm)xave emfs of $E_1\,=\,9.0V$ and $E_2\,=\,12.0V$ and the resistors have values of $R_1\,=\,25\Omega$,$R_2\,=\,18\Omega$, and $R_3\,=\,35\Omega$
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Repeat Problem 29, assuming each battery has internaz)fxworf2 ,3el 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. io;ltu+-+ u j 8jmr)ku19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curoaztmpg 2ui5. *3f +jlrents $I_1$,$I_2$, 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 v j-sedmurh.,8/mu/f $I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, with unequal emfs of 2.00 V and 3.00 V, are connect1ybs p ml1q 9kd+kni1,e2-oyred as shown in (Fig. Below). If each internal resistancysm2n y1-ko b1,pi l +9erqkd1e 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, 2fr gb a-+qbvn:0uboh)y1(og 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 netf)awqab dqa ls87g11i69a dukxpmz.no )c)8 2work of (Fig. Below), calculate the voltaqnzd.ua c s1fpd 98))2aka7xwba1ol 8 )iq6mgge across each capacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of a circuit is to be reduced from 4800 pF t 6due(eqld 67mo 2900 pF.m uqee76 (l6dd
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 accidentm 3yal,9, mt gampc70bmx99 eyally 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 ciejvh ys art+ m6x .g6)i70oc:nrcuit shown in (Fig. Below).

  In (Fig. Below), if lsz9 xlryp+22 /ynx6d$C_1=C_2=2C_3=22.6\mu F$, 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), supp 7;odrryq.do k1tk0 v/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), let 497c qs9nhoxi*dr 3 h2/bxoyu$V\,=\,78V$ 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 showzju0f2 .m nft2n in (Fig. Below). u2f2t fnz 0m.j
(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 anflnw0k(( hp u+cb7z 87 ffaj6 battery. It is desired to stok8pul7n+ nabf0wcjh(z7 (f6fre three times as much energy in a combination of two capacitors by adding a single capacitor to this one.
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is connec: dwj+o0 diyu sc22jd1:lm3ycted in series with an unknown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If theoc 1 +djcymdu3sd2 w2i:jy l0: 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often czn,u g):yd3pqonnected as shown in (Fig. Below). The leads are said to be capacitively coupled. A time constant of 3.0 s is typical and allows rapid changes in potential to be recorded acc udnzq,y3:g) purately. 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 0fvnu+wwhe r1cf4f8+om,p /cresistance 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.)q-r i:y.5s ked ib*vs Below 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)tgqz-f2 /gn u capacitors are arranged as shown in (Fig. Below). Then a potential difference of 24 V is applied across the combination as shown. -/ufg)2 tq zgn
(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 of66o;b arbtwbdr ht91/ a voltmeter on the 250-V scale if the meter sensitivitydar1/6bwt6;tb 9 b ohr is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a senfdcxhc;0dp+ j/r+c m :sitivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internala86d ;0zv6lkuj ep6 (9 lkeznjed/:f b 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 sensite68v9f msedmbzqbl .*og8g3vt /n-a)ivity 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 consists os1f tr44te: jtp:nv (hf 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 connechl: )bvupk 88ated 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 381f:leo(h;zbu we bfresistance 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 Examplewtat8 tb 53dgu(:v h-x 19–15 have to be in error by lvwtxgaudt(5- :b38th ess than 3%? $\approx$    k$\Omega$

  When the resistor R in (Figa d*7k6zvgvjro/gobjc 44 8 r:. 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 im6 :paiqz8u j;eo lsc2:s:-h difference between two points on the human body. The resistance is about z8j -slqaieso :i u:h ;pm:26c$2000\Omega$, 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, or2dah(zq-yysh ;rf hn :,vlq8 9 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually or in paralle y8v 9:zdh(q;an ,frqhsyhl2-l.
(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 icz+*c2mq: dx vs 95 m from an electric outlet. Each of the wires connecting your appam:x2q c*cvz d+ratus 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 haza nt1+k2*g(fc(jfmm qwrd in hospitals, particularly to patients 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 nf mt(k 1w(+qmfncgj2 *ot 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 expend to charge a v-wbx 2;m-)hzxh o 7gg$0.40-\mu F$ 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 beaty0nt.kq1rjo 0sv 9pni3*g g;xl7o2 in s/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 bockb,o b+l0ey2m h zn1(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 measurements 3.y hyp4x 55ijmx/u cmd:g5zwof resistance. The unknown resistancxx4 wjmg. pmy3yzu5i c /h5:5de 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 0m +kvv kd: cor)+lm.0:y0;ggjx r1s kj.920 mm in diameter is placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Bevk.j0rcdksx :1jl+mmy+ 0 g;k)or g:vlow). 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 efflp0,z;gxh h:vective capacitance which can be obtained by connecting four identical capacitor0x;v h:,zh lgps, each having a capacitance C?

  The variable capacitance of an old radio tuner consk (vj i*ca*z)rsfv4,s ists of four plates connected together placed alternately between four other pl,s ik cz sv*r4*ajv()fates, 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 is drawn from it and 47.3 V whb c;yj - 8pmqd(giav)4en 2.20 A is drawn. What are the emf and internal resistance of a(gc ; b-4jdyv8m)ip qthe 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 t.fl1 q;0ynfhkcqy/ +rhe $4.0-k\Omega$ resistor in (Fig. Below) is 3.50 mA. What is the terminal voltage $V_{ba}$ of the “unknown” battery? (There are two answers. Why?) [Hint: use conservation of energy or Kirchhoff’s rules.]
right $V_{ab}$    V
left $V_{ab}$    V

An air-filled parallel-plate capacitor mvf luh).dw86zk /x zg9qk;a y54 f1djhas 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. Belozk*cw(/ntzs 8nlg 5t6w), determine
(a) the current through the 14-V battery $I_1$   $ \times10^{-5 }\;A$ ----待选择----downupward 
(b) the potential difference between points a and b, $V_a-V_b$.    V

  A solar cell, 3.0 cm square, has an output of 350 mA s erob5x-r. rpgkjci6 4h3-1cat 0.80 V when exposed to full sunlight. A solar panel that delr-e3 514brxo6 c hs-i.rpkcj givers 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 fixehw5w1junxy) px )qg;;/hh*x7wgm .azd 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) dv:e(wl 3pga4 uses a neon-filled tube as in (Fig. Below b). This neong pelv(4ad w:3 lamp has a threshold voltage $V_0$ for conduction, because no current flows until the neon gas in the tube is ionized by a sufficiently strong electric field. Once the threshold voltage is exceeded, the lamp has negligible resistance. The capacitor stores electrical energy, which can be released to flash the lamp. Assume that $C=0.150\mathrm{~}\mu\mathrm{F},R=2.35\times10\mathrm{~}^6\Omega,V_0=90.0\mathrm{~V}$ and Ann meter=105 V
(a) Assuming that the circuit is hooked up to the emf at time $t\,=\,0$, at what time will the light first flash?    s
(b) If the value of R is increased, will the time you found in part (a) increase or decrease?  ----待选择---- increase decrease 
(c) The flashing of the lamp is very brief. Why?
(d) Explain what happens after the lamp flashes for the first time.

a
b

  The current through tmtthd r0r+ r;1he $20-\Omega$ 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.nsjvt+.cpzoxd* ul .c 1ky 509 Below), the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalen/ m8f pjvd,a*+e;y9a f 1uwofzt 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 shown in (Fig,1gxl g:, 7ifen-ll do. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeter reading, the value of R will not qui ,lx: -ogg1eld,nfi7l te 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 2nr k3)2nab :6(rgfs6 jq t;ykh.5 W and 3.0 V is operated by a 9.0-V battery. To light the bulqt6(s; ka3nf:hy)knr 6gj2 b rb at its rated voltage and power, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$