Explain why birds can sit on power lines safewi /:c4m* taeely, whereas leaning a metal ladder up ag*ei/ a4:e ctwmainst a power line to fetch a stuck kite is extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree li4af :gbfay (t)ghts connected in parallel versus t)atg(4 yff ab:hose connected in series.

If all you have is a 120-V line, would it be possible to light several 6-V lamps2ig+mr*zn lf ho 5hh+5 without burning them ou5+n* hzofm2 h5+ligrht? How?

Two lightbulbs of resista7 t/9tn, hm( ds)luudb( n2exlnce $R_1$ 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 don,l7v,: a 7bgti zs89ghvins h,2md+huble outlets. Are these connected in series or parallel? Hgz:i27vbhnv nd,7i gth s,89, +lhmas ow do you know?

With two identical lightbulbs and two identical battqbk-f:e i- u/series, how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (-/si ufq-:bk eAssume the batteries have negligible internal resistance.)

If two identical resistors are connected in mhm b66 ; mf9/lnokhtrj 6)*isseries to a battery, does the battery have to supply more power or less power than when only one of the resistortj/m f h6)ih *6km9sn6l ;orbms is connected? Explain.

You have a single 60-W bulb on in yoejyejjs f3j 51 04c1vsur room. How does the overall resistance of your room’s electric cir 1fcj45es0vs3 j1jyje cuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s lmi3 c/z j;0cuddso b8e4g 5*eloop rule (such as in Fig. Below), does the sign (or direction) of a battery’s emf depend on the direction of current through the battery? What about the terminal voltage? l3 0/dejemzcg5bs;c8 ido4 u*

  Given the circuit shown in Fig. 19–36, usf,wy,s(s ;forur0n h s);:4vwyec *phe the words “increases,” “decreases,” or “stays the same” to complete tvh;w ;fu*f e,r(:srnsc osp )04hy,yw he 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 what use are they 7kw03pq4nkfa t 0p*nxconnected in parallel? Does it matter if the batteries aren4q0 pk7apw3n *fx kt0 nearly identical or not in either case?

Can the terminal voltage of a battery eve*-2+-jixr as0k p5ytp n q/e 0a0pgwyar exceed its emf? Explain.

Explain in detail how you could measure the internal resistance of arlhs p 6h4jws 8ca297k battery.

Compare and discuss the formul0oj h+b m*gvi0as for resistors and for capacitors when connected in series an hi 0o*g0+bvmjd in parallel.

Suppose that three identical capacitors are cbpoyp oe 8m+5: l6g.hx0 ngmi8onnected to a battery. Will they store more energy if connected in serii6 lymhg 05mpg8 .noe:+pxo8b es or in parallel?

Why is it more dangerous to turn on an electric appliance wznq 069fjjea8x +,r wshen you are standing outside in bare feet than when you are inside wearing zwa+jr9s j fxnq ,6e80shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphone. The chauj:37cq 0g ympnging air pressure in a sound wgm p30qu ycj7:ave causes one plate of the capacitor C to move back and forth. Explain how a current of the same frequency as the sound wave is produced.

Design a circuit in which two diffe)bub7i-e .h+y :87yssvlvph vrent switches of the type shown in (Fig. Below) can be used to operate th-:ibs v)hh v8psb+uye .vl 7y7e same lightbulb from opposite sides of a room.

In an RC circuit, current flows from the battery until the c ghp/c413d6v x v(itz1n*lf ppapacitor is completely charged. Is the total energy supplied by t /(tv4c6lpnf1 3ppv1xh*digz he battery equal to the total energy stored by the capacitor? If not, where does the extra energy go?

What is the main difference betwe 1g:ag2lxqn0a en an analog voltmeter and an analog ammeter?

What would happen if you mistakenly used an ammeter where you needed to 1cchttqpz94(nt ix3* gs( , dwuse a voltmetp*stt(c1 i3 tgqw cz,4 9nx(dher?

Explain why an ideal ammeter would have zero resistance and an idealdzx9e.t*w644ay f fgn voltmeter infinite resistw n9* 46fd.tfxezyag 4ance.

A voltmeter connected across a resistor always reads less .bzqy/.f7eh nthan the actual voltage across the resistor when the meter is notqb.h7 z yfn./e present. Explain.

A small battery-operated flashlight requ:unfz9c31) ujkl;m z iires a single 1.5-V battery. The bulb is barely glowing, but when you take the battery out and check it wi; ) fc9i3jz:lmunk1z uth a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an inter.yjt2;p(vw ru) )vo.vxu7c3ysqjq z; nal 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 resistaj(b 20/t jgejbnce 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 a 3 v30l)eq jgj +mhc4px$680-\Omega$, 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 uq46om xt5,yg+uj1 hg 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 ojpdoc62; ) hygw gh-6nf $12.0\,V$ 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 acrom7t4s iue02esw ocay n+; t1n;ss 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 parallel iq)hc-yblwla; kdd)ix9 s (k w-6e/ h6to a $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?
$V_R $ =    $\Omega$
firaction wasted =   

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

  A close inspection of an electric circuit reveals th)qr/.r ,qyxp kat 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. Below). Answl - a3a 74cixbs6w:cvw: udb+ver qualitatively: uwv+7xac4: sbic6 b d3valw :-
(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 thegul n5;t +. b;anft0mr circuit connected to the battery in (Fig. Below)? Each resistance hasl.;+5 t;g arntfmbu 0n $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connecteu6x* fdnb lu9j,p +th9z8rx9v d to a battery as shown in (Fig. Below). Qualitatively, what ha8 rd*j9x99v huf zuxlpn,t6+b ppens to
(a) the voltage drop across each of these resistors, $V_{left}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0 
(b) the current flow through each, $I_{left}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0 
(c) the terminal voltage of the battery, when the switch S is opened, after having been closed for a long time? terminal voltage  ----待选择----decreaseincrease0 
(d) If the emf of the battery is 15.0 V, what is its terminal voltage when the switch is closed if the internal resistance is $0.50\Omega$ and $R\,=\,5.5\Omega$?
$V_{terminal\,closed}$ =    V
(e) What is the terminal voltage when the switch is open? $V_{terminal\,closed}$ =    V

  A $2.8-k\Omega$ and a $2.1-k\Omega$ resistor are connected in parallel; this combination is connected in series with a $1.8-k\Omega$ resistor. If each resistor is rated at $\frac{1}{2}W$ (maximum without overheating), what is the maximum voltage that can be applied across the whole network?    V

  Calculate the current in the circuit of (Fig. Below) ande636jz vsv.hq show that the sum of all thv .jz6h3sq ev6e voltage changes around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal voltage of each battery in (Fig.x7z9 ggdrth3+wib v+wb94 9ud Below). 18V battery =    V 12V battery =    V

  (a) What is the potential differ:g) e sdfd9 f/j4kxaj,ence between points a and d in (Fig. Below a) (sa d9:, k4fjfs)egjd/ axme circuit 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 c2ao8z 7e y5qvbetween points a and z8eya72cqo 5vb. Each resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directf;thv f;k9+ xgions 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 s)7c3e f8dz i cg4/yax *bjoa)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 directioje f.q5 -5p 1ekdzo0kdns of the currents in each resistor shown in (Fig. Below). The batteries have emfs5je5d0 k.-qfe 1zdopk 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 bm- r ,0:4t/owqd(z 1:wf zuswftcpo0oattery 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 ea.2b7,j)h) w0jld lhyhze; kyfch resistor of (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curo udft 2.opa,,rents $I_1$,$I_2$, 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 current1c7 doft/dh ;evj4( pokeh+;1xp- evi $I_1$ 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 3tolfpo85)g6x (w h 7sq.00 V, are connected as shown in (Fig. Below)l )sf75t6o ghp q8x(wo. If each internal resistance is $r\,=\,0.100\Omega$ and $R\,=\,4.00\Omega$, what is the voltage across the resistor R? $V_R$ $\approx$    V (retain two decimal places)

  (a) Six $4.7-\mu F$ capacitors are connected in parallel. What is the equivalent capacitance? $C_{eq}$ =    $\mu F$
(b) What is their equivalent capacitance if connected in series? $C_{eq}$ =    $\mu F$

  You have three capacitorss7lip :ulapk;32 ugn c6;d k;x, of capacitance 3200 pF, 7500 pF, and $0.0100\mu F$ . What maximum and minimum capacitance can you form from these? How do you make the connection in each case?
$C_{max}$ =    $ \times10^{-8 }\;F$ in  ----待选择----parallelseries 
$C_{min}$ =    $ \times10^{-9 }\;F$ in  ----待选择----parallelseries 

  A $3.00-\mu F$ and a $4.00-\mu F$ capacitor are connected in series, and this combination is connected in parallel with a $2.00-\mu F$ capacitor (see Fig. Below). What is the net capacitance? $C_{eq}$ =    $\mu F$

  If 26.0 V is applied across the rhx51t xp+en0d cr: 2cwhole network of (Fig. Below), calculate the voltage + e c:xh10tdc2 rxrnp5across each capacitor.
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portioqq*d0tvs8kke:m f t1; n of a circuit is to be reduced from 4800 pF to 2900 p1f80vk eqt*s; k qt:dmF.
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 accidq dept*q23imws r/6-oentally constructed using a $5.0-\mu F$ capacitor instead of the required $16-\mu F$ value. Without removing the $5.0-\mu F$ capacitor, what can a technician add to correct this circuit?
   $\mu F$
conneected in  ----待选择----parallelseries 

Determine the equivalent capacitance of the circuit s(+o9z ng ytidsf9d0p5 hown in (Fig. Below).

  In (Fig. Below), if +l5 3qsao f:dv$C_1=C_2=2C_3=22.6\mu F$, 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), supbkrzm.i8ey ) 2f4 8/l 7kwpvorpose $C_1=C_2=2C_3=16.0\mu F$, 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 m 4fm utlm:)(b$V\,=\,78V$ 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 plate8 -nrs)k goehmu7fa d/mp.x8,s, each of area A, are connected as shown in (Fig. Below). h,r/ meo) px.87u8 afsn- mgkd
(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 rzl9x8x:h f/maj5p +.:1bk) pl cpua vcapacitor hooked across a battery. It is desired to store three times as much energy in a combination of two cau.a lxlb1:c5 rzh m/+8 vxj)9pp pk:afpacitors 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 zt;t:fg ;yl)ks,ag,aseries with an unknown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its plates, what is t kal a:,s)gz yf;t;t,ghe unknown capacitance?    pF

  Electrocardiographs are often connected as shown in (Fig. Below).upn /srv :w4aba(:*g+;pa jk l The leads are said to be capacitively coupled. A time constant of 3.0 s is typical and allp(+ak:bjws* pgr4; uva n :a/lows 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 tofeg1ilsd18de p/u d5v/rb f 62tal 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 Fi4lb oi/ h2 i6ceg 4hz)q mons,gyr7l*8g. 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 capacitors a;/wzrn-qh r(ft pskmht8i z3 h ucb9wg5 h0-/,re arranged as shown in (Fig. Below). Then a potential difference of 24 V(htzhw b t-cpumrzi8n //q s5 -k 0h9f3r,w;gh is applied across the combination as shown.
(a) What is the potential at point a with switch S open? (Let $V=0$ at the negative terminal of the source.)    V
(b) What is the potential at point b with the switch open?    V
(c) When the switch is closed, what is the final potential of point b?    V
(d) How much charge flows through the switch S after it is closed?    $\mu F$

  What is the resistance of a voltmeter on the 250-V scale if the meter sensr:p obwe 69;u wdp2:mpitivity 6r ;:dmwep 2pb:w9puois $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivitylm7 :jdajb7hef ft4: : of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal/c :cwx,,r- tj+im hmlnlb)4z 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 o) 4 pwq 3dw;lagau:l+iee*bi ;f $35k\Omega/V$ 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. ivha oc(4), ( kf4kqvo42pxjv It consists 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 intm15u5gqbp.a yngqkd(dn ,-do g p9,z ;ernal resistance is connected to a $R_1$=$38-k\Omega$ and a $R_2$=$27-k\Omega$ resistor in series. What reading will a voltmeter, of internal resistance $95k\Omega$ give when used to measure the voltage across each resistor? What is the percent inaccuracy due to meter resistance for each case?
$V_1$$\approx$    V (retain one decimal places) % error    % too  ----待选择----uplow 
$V_2$$\approx$    V (Round to the nearest integer) % error    % too  ----待选择----uplow 

  An ammeter whose internal resistance is zns 9jf,dksu0;lq,zbt90s x 5 $63\Omega$ 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 resistanczs+fvme2( o( se should the voltmeter of Example 19–15 have to be in error by less than 3%? vsf(o m2+esz( $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) if9r69p f 9g t.2d5cpcosv3 aev0gk5 ses $35\Omega$, 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 differ,x:vtai g )u+qfmjf b)mwbzr2, 597ptence between two points on the human body. The resistance q:7fz2pj ,b)i5w9t)m a uxgvm+ftr,bis about $2000\Omega$, and you only have a 9.0-V battery. How can you connect up one or more resistors to produce the desired voltage?    k$\Omega$

  A three-way lightbulb can produce *v+ln3 r e e;d2vyt62pjrx( os50 W, 100 W, or 150 W, at 120 V. Such a bulb contains two filaments that can be connected to y6r e (2v+ *nl;dtr ejsvxp32othe 120 V individually or in parallel.
(a) Describe how the connections to the two filaments are made to give each of the three wattages.
50 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
100 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
150 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
(b) What must be the resistance of each filament?
$R_{50W}$    $\Omega$
$R_{100W}$    $\Omega$

  Suppose you want to run some apparatus that is 95 m from an electric outlet. 0 vpxcl4el+:yEach of the wires connecting y+lx4ce:vlyp 0our 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 t0 gxtbqrn1-h0mhl2n + o 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 not there in the first place). If a nur x br 0gn21tqhlnm-0+hse 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 e 0wzu1*szzt o *h-vt8jxpend 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 s-8ypdo/vi, j 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 resistance ip /.he w)pwvziakt1, k79djl(s $950\Omega$
(a) What current passes through the body when the person accidentally is connected to 110 V?   A
(b) If there is an alternative path to ground whose resistance is $45\Omega$, what current passes through the person?   A
(c) If the voltage source can produce at most 1.5 A, how much current passes through the person in case (b)? $\approx$    mA(retain three decimal places)

  A Wheatstone bridge is a type of “bridge circuit” used to mqq3z0cd( ii1+ (aoirsake measurements of resistance. The u(is oqr (1q0d+iizc3anknown 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 wire 0.920 mm in diameter is placed as the unk)5x)yyhv/yof6fz u-p / sfa3w q3tg2nnown resistance in a62v )a35)/ q gwhofxy3t-znsff/yyup Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 have resistance of $38.0\Omega$ and $46.0\Omega$ respectively. Balance is achieved when $R_3$ is $3.48\Omega$ How long is the platinum wire?    m

What are the values of effective capacitance which can be obtr/yu10xigvjj hg3 8v1 ained by connecting four iden 1 /grxj8ijh3vgu1y0vtical capacitors, each having a capacitance C?

  The variable capacitance of an old radio tuner consists of four nm,z(* tzvh w9cc7zx6plates connected together placed alternately between four other plates, also connected together (Fig. Below). Each plate is separated from its neighbor by 1.5 mm of air. One set of plates can move so that the area of overlap of each pxn*h,w zc6 zmc( z7tv9late 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 j t.jik2v. : dd7v1vkkoggt 6(V when 2.20 A is drawn. What are thiv:g.1 vo v dkj7t6jk2tk. (dge emf and internal resistance of the battery?
r =    $\Omega$
$\varepsilon$ =    V

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

  The current through theln.1h 0uo 3 gkrku8:ek $4.0-k\Omega$ 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 hasa ruyhb j7j+;- 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), determin,n3pv-d dee;ux/ya piz+ l2a2e
(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 350n9nrt/fw q 0v:ftl7e g. 7kp0y mA at 0.80 V when exposed to full sunlight. A solar panel thar9tfle0p w 07tnvy:qkn. g/7ft 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 12.0 V, but you 8nb x2p534s*npl pyuaneed $V_T\,=\,3.0V$ 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 (Fig. Belowscs9 n)2yt*yd-h9 g hw b). This neon lam wc9ht)*hg29- y snydsp 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 ts7n trttqn )cy73s9/ehe $20-\Omega$ 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), the0 7fhxp: bs3):rr4xy0tta olc $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance of the circuit shown in (Fixr4 l6 yan1az0 -bt) 7capujk8g. 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 ammetea dsstizkv /*bt 0,9zbmf(u02r can be connected as shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, and I is the ammeter reading, tfds ms i/*ab, b09tu2tkz z0v(he 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 3p.hwn549 k* aq:nhr -xqq5)st. / sbx-pk blan.0 V is operated by a 9.0-V battery. To light the bulb at its rated voltage and power, a resistor xt4 .p rl. kbb9nxn5sqah)s / -naqp:hk*w5-qR is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$