Explain why birds can sit on power lines safely, whereas leaning a l6f5wlpv:-os metal ladder up against a power line to fetch a stuck kite is extre s :fp6ol5wl-vmely dangerous.

Discuss the advantages and disap*:q7ox+fbkng rm1 *ddvantages of Christmas tree lights connected in parallel versus those connected in segm+17b *fk dxonrq :*pries.

If all you have is a 120-V line, would it be possible to lightsnyhpon/yl :9cr;2sz -b/t j6 several 6-V lamps without burning them oun6ylop/z h s;tn:c/ jybr-s92t? How?

Two lightbulbs of resistanceahqnkz5fvof6 0k r9 08 $R_1$ 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 e5;zuzls5p)y l.tw+u p6l qny 7qc1)my6gs2 xthese connected in series or parallel? How do you know 5lp6 7c5gw )y;qn+y yelzzxqt2suum1ps).6l ?

With two identical lightbulbs ankw5f6 kx kdgg-t :86bgd two identical batteries, how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power ouxgwk58 -d6 6gtgk :bkft? (Assume the batteries have negligible internal resistance.)

If two identical resistors are connected infvoz.-gk7 d* c+2*h z( k h5ekvzcfux; series to a battery, does the battery have to supply more power or less powz;dv(- +2.5c* vf eck xgfz*kokhhuz7er than when only one of the resistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the overallsdz7o pu os*7aoda 5(8 resistance of your room’s electric circuit change when you turn on an additionald*s uo oao75sadz78(p 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below), doeorr5 kqn,)xb 8s the sign (or direction) of a battery’s emf depend on the direction of current through the battery? What 5qob8k, r)nxr about the terminal voltage?

  Given the circuit shown in Fiuo 2cq6 x+igo4g. 19–36, use the words “increases,” “decreases,” or “stays the same” to complete the following statements: q4 c2oxio+ug6
(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 arecfn)+dx dk1j h5/.yy n they connected in parallel? Does it ma/ hyyd+xn .1f5cn)jdktter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever exceed its emfrx f00w-n(2ly5qe .j ikfg 1jt,cp4wq? Explain.

Explain in detail how you could measure the internal resistanc. 9 8dtfon,um4bl ka+ve of a battery.

Compare and discuss the formulas for resistors a4j:wmyp6(ky8 hvzo h)nd for capacitors when connected in series anvw)okjmy6:8z yhh4p (d in parallel.

Suppose that three identical capacitor 0a0xm un8jyx3s are connected to a battery. Will they store more energy if connecj3am 8u0y0x xnted in series or in parallel?

Why is it more dangerous to turn on an electric appliance when yo3vc-am,5x5tq7:vsnuf chd (bu are standing outside in bare feet than when you are inside wearing shoqvsc- fhtn:cax 3 ,57 m5(bvudes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser)pmkxdu/3d e, :hiyt,2 microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to move back and forth. Explain how a current of the same frequ2hi:/pe y ,mdtk3u,dx ency as the sound wave is produced.

Design a circuit in which two different switches of the type shown in; pzoe5yy( uj68wzci (olv9- e (Fig. Below) can be used to opera-z(8(o lzwp9y5uo i veyj;ec6te the same lightbulb from opposite sides of a room.

In an RC circuit, current flows from the battery until the capacitor is com,z(r(*y+i7 f64sicxxsp t6o2js ol trpletely charged. Is the total energy supplied by the battery equal to the total energy stored jrsf( or2px(7t,+oc *lzis4sx 6 tiy6by the capacitor? If not, where does the extra energy go?

What is the main difference between an analog +0ebti*- ,fridka. oe voltmeter and an analog ammeter?

What would happen if you mistakenly used an ammeter where youky ;bql3dab); 3:o bqsdbzb/ b;vq 56y needed to use a voltb6:alsdby;qv /;)zbk y q 3boqd5b3;bmeter?

Explain why an ideal ammeter would have zero resistance and an ideal voltmeter xu yhp fk7t2uvs6; 6n3infinv7u6 pyhku fts 3n62;xite resistance.

A voltmeter connected across a resistor alwa4/8lbcb sv uv3ys reads less than the actual voltage across the resistor when the meter is notslvv/3b 8cbu4 present. Explain.

A small battery-operated flashlight requires a single 1.5-V bkaetclzl nits) 7wj9pn+ k6873y)mu/ attery. The bulb is barely glowing, but when you take the battery out and check it with a wtp36i e)8u n9lzk+stla )j7 ny7/mkcvoltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an intlt9d ode39 ,ew(d6)rh7tx u ;bdu8ngzernal 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 resistanceie/k*n1xdd /fheqq(b0k *q. 9twx eh. 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 kso 6o8dt 8d03o)f-ekpeo z,va $680-\Omega$, a $940-\Omega$ and a $1.20-k\Omega$ resistor. What is
(a) the maximum,    $\Omega$
(b) the minimum resistance you can obtain by combining these?    $\Omega$

Suppose that you have a xj,*+o,esu ,(nuiej v1qg(49 upybn j $6.0-V$ 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 emm4:gr)/-cfw,f +lm8hm cnx z lf of $12.0\,V$ shows a terminal voltage of $11.8\,V$ when operating in a circuit with two lightbulbs rated at $3.0\,W$ (at $12.0\,V$) which are connected in parallel. What is the battery’s internal resistance?    $\Omega$

  Eight identical lights a)+h8 8cwdt4uv )hmn nfre 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 parallel nhb 4c9sug 0fr,g8(df 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 $ =    $\Omega$
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 thct9j*z2sc gg b6co+.wat 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 rk-w*w :jhpuu ,esistors shown in (Fig. Below). Answer qualitatively: *h-k:up, uwjw
(a) What happens to the voltage across each resistor when the switch S is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(b) What happens to the current through each when the switch is closed? $V_1$  ----待选择----increasedecrease  $V_2$  ----待选择----increasedecrease  $V_3$  ----待选择----increasedecrease  $V_4$  ----待选择----increasedecrease 
(c) What happens to the power output of the battery when the switch is closed?  ----待选择----increasedecrease 
(d) Let $R_1=R_2=R_3=R_4=125\Omega$ and $V\,=\,22.0\,V$. Determine the current through each resistor before and after closing the switch. Are your qualitative predictions confirmed? Notice that the current through each of the parallel resistors is half of the total current, within the limits of significant figures. $I_1$ =    A $I_3$ =    A $I_4$    A Notice that the current through each of the parallel resistors is one third of the total current, within the limits of significant figures.$I_1$ =    A $I_2$ =    A $I_3$ =    A $I_4$ =    A  ----待选择----YesNo 

  What is the net resistance of the circuit connected to the battery in z/ l7tiqidywk2.8jk7n-ymo 8(Fig. Below)? Each resistance hasq7 2i.kyt on-id lky/87z8wmj $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown in (Fig. Below). lmcq 5w0 mk9y a/s+w5f0sjuf8 Qua8s l0mw qu0j+cfw9 y5am5s/kflitatively, 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 thei )sto fb2fc9- circuit of (Fig. Below) and show that the sum of all the voltage changes around the circuit is zero. 9iof-) btcf s2
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the terminal voltage of each battery in (Fig. Belov8 4fcmv(5t lxw). 18V battery =    V 12V battery =    V

  (a) What is the potents8-g6,muziu t ial difference between points a and d in (Fig. Below a) (samu m6i-s utzg,8e 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 (Fig3:. l xek.1poo6 9qmj r2ehjcb. Below), find the potential difference between points a and b. Each re93xje l 2merbokh. cj6p1 .:qosistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directpv ;)8 bxksx:f 3i,o7qwhfc; zions 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 assumin7o( )sh.uprll rp-e;n g that each battery has an internal resistance $r\,=\,1.2\Omega$.
$I_1$ $\approx$    A  ----待选择----leftright (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftright  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftright  (retain two decimal places)

  Determine the magnitudes and directions of the currents in each resupl 3 okj-kr(fd * uw;jjv1*f5istor shown in (Fig. Below)f;-fd*jv*pju13( ur w5okj k l. The batteries have emfs of $E_1\,=\,9.0V$ and $E_2\,=\,12.0V$ and the resistors have values of $R_1\,=\,25\Omega$,$R_2\,=\,18\Omega$, and $R_3\,=\,35\Omega$
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Repeat Problem 29, assuming each battery h bfk(2nrse 1p* 2cr ha8d6lp, c9cyly)+:urcbas 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. Belm0qm-ueya/cnrb,/h h 6 nb2 /bow).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the currents :* --*2qy-rs quw( 31rs hygtjjpeqki$I_1$,$I_2$, 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 )/a- nptz)+omv-fdd u$I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, with unequal emfs of 2kz(*ukh;j8lbgk4p w8)tf 1qp .00 V and 3.00 V, are connected as shown in (Fig. Below) (k; ft*u hj8 kg4ppk)wzq1bl8. 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 capacitors, of capacitance 3200 pF,6rw c/ kxp 6ym09ztxth9d3uh6 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 whkz ,l *-dfikb6xp pe nrd36e++ole network of (Fig. Below), calculate the voltae e3d *, +kkz 6fi6bp-+rdnlpxge 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 2k jz qk yd6bbpfn6y2nk187p0be reduced from 4800 pF to 2900 pF. f0yp7dkk n6zy 8bq6p jbnk2 21
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 constructed using g3.n;esq6pi g a $5.0-\mu F$ capacitor instead of the required $16-\mu F$ value. Without removing the $5.0-\mu F$ capacitor, what can a technician add to correct this circuit?
   $\mu F$
conneected in  ----待选择----parallelseries 

Determine the equivalent capacitance of the circuit shown in (Fim+za5u;+o ecgdaaft 5yv qvg;x,80, lg. Below).

  In (Fig. Below), if o/ /ljt2cql- vsd-. ry$C_1=C_2=2C_3=22.6\mu F$, 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 uup63exe8n )f+d-of.e*p t bl$C_1=C_2=2C_3=16.0\mu F$, 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 .tx+ ccy-p +b6 *ykkwf$V\,=\,78V$ 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 showi n+ him( e*dqxj+uzbvap5+g t-9x.5in in (Fig. Below). xi.-59i*zt+mng(vdpa+ +h x jueqi5b
(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 acr1 7kx/ dezdve5 jag*+poss a battery. It is desired to store three times as much energy in a combi /jg+v75d*zk1expeda nation 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 connected in series with an unkz.acbs)o h(h3 +go 4amdhuk 05nown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 185-pF capacith0dzsu 4a hgb 5o ohm3().ack+or stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often con a2fhpcgli8(0nected as shown in (Fig. Below). The leads are said to be capacitively coupled. A time constant of 3.0 s is typical and a2ha8( 0l cpgfillows 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 rx;s )msi)uvw *g vspap36)9ras Fig. Below b), the total resistance is $15.0k\Omega$, and the battery’s emf is 24.0 V. If the time constant is measured to be $35.0\mu s$, calculate
(a) the total capacitance of the circuit    $ \times10^{-9 }\;F$
(b) the time it takes for the voltage across the resistor to reach 16.0 V after the switch is closed.    $ \times10^{-5 }\;s$

a
b

  The RC circuit of Fig. Below a (same as Fig. Below b)vuti 4n ,yxomj/-a8j) 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. Bem+ nmbj5jr 8u:low). Thenr mu5 b8:mjnj+ a potential difference of 24 V is applied across the combination as shown.
(a) What is the potential at point a with switch S open? (Let $V=0$ at the negative terminal of the source.)    V
(b) What is the potential at point b with the switch open?    V
(c) When the switch is closed, what is the final potential of point b?    V
(d) How much charge flows through the switch S after it is closed?    $\mu F$

  What is the resistance of a voltmeter on the 250-V scale iumwhhv ,,3*aumqv ,cj43 t8jsf the meter sensitivity is ,vsv 3jqu uh,m*8,jmtwh c 34a$30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sen y)k-zeobh;f *r1wqy: sitivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an ieai.3z +s /ulinternal 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 s((a+kbn s-6 (eqyq ibiensitivity 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 af ,zb8hec38x/kuphe /p 9x,vconsists 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 negli)gwghcm33r) )mvsl.z 0e 6or jgible internal 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 res/zpv)okq ,l j)3vi gulu3w1m* istance 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 Exampuh- ao;r;fop3 le 19–15 have to be in error byp-;a oufr;oh 3 less than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) rab /(bp+r k8.i1enj3jgg;b9bnji.lis $35\Omega$, the high-resistance voltmeter reads 9.7 V. When R is replaced by a $9.0-k\Omega$ resistor, the voltmeter reading drops to 8.1 V. What are the emf and internal resistance of the battery?
r $\approx$    $\Omega$(retain one decimal places)
$\varepsilon$ $\approx$   V(retain one decimal places)

  Suppose that you wish to apply a 0.25-V potential difference between two po-hq t:cau 0 yls l)sfdor,1wby -1rl(8q+/ fgdints on the human body. ) dld,tsgar80ylow (q/:fsrqy-clf - 1 buh+ 1The resistance is about $2000\Omega$, and you only have a 9.0-V battery. How can you connect up one or more resistors to produce the desired voltage?    k$\Omega$

  A three-way lightbulb can produce 50 W, 100 W, 5 q 8f+;uqafne6ba.az msx2lm8n r,n ;or 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually or in parallel.nq68xsrqenmaf5l+ fnuabm;. ;,82a z
(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 obe/+kz-b i,h8ps+ cl run some apparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 120-V source has a resistance per unit lh k e/p+oislc+ 8,bz-bength 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 rqee/0v l,7d:x/ yqppv)s /yay +m.bmpatients 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 connectiy7)mda/ lryq + :vp/m,eq0p/exb y vs.on 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-l0pd6 vdj7m:/olzo/+hlu-fp V battery expend to charge a $0.40-\mu F$ and a $0.60-\mu F$ capacitor fully when they are placed
(a) in parallel,    $ \times10^{-3 }\;J$
(b) in series?    $ \times10^{-4 }\;J$
(c) How much charge flowed from the battery in each case?
$Q_a$ =    $\mu C$
$Q_b$ $\approx$    $\mu C$(Round to the nearest integer)

  A heart pacemaker is designed to operate a 2o+o4dt ;zwf o5b:dkyt 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 -71by/ik y/wee7 muty’s body 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 toywfqq*r91/q6au: ic 6c.zl 2q9 s1n go7rggrj make measurements of resistanc9j:qg qcr 1f*6 l9 zyqsi71gu6raw/ng2o qcr.e. The unknown resistance to be measured, $R_x$, is placed in the circuit with accurately known resistances $R_1$ ,$R_2$, and $R_3$(Fig. Below). One of these, $R_3$, is a variable resistor which is adjusted so that when the switch is closed momentarily, the ammeter Ann Meter shows zero current flow.
(a) Determine $R_x$ in terms of $R_1$ ,$R_2$, and $R_3$.
(b) If a Wheatstone bridge is “balanced” when $R_1\,=\,630\Omega$,$R_2\,=\,972\Omega$, and $R_3\,=\,42.6\Omega$, what is the value of the unknown resistance?    $\Omega$

  An unknown length of platinum wire 0.920 mm in diameter is placed as the unknowrdl.0zbi9)n2xln 7g xn resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 have resis.zxg0d nl9 n)b7ir2xltance 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 i 925su, mim7 *qncwcnwhich can be obtained by connecting foucmmw qs,n29c *u7i5inr identical capacitors, each having a capacitance C?

  The variable capacitance of an old radio tuner cocyddm o1g to95zt*hah2 +gzhqz,8. 6fnsists of four plates connected together placed alternately between four other plates, also connected togefqhma 9to 1hz 286 o5,dyg*dgctzz.h+ ther (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 when 2.20 A isyqbo) c68y1 ub drawn. What are the emf and internal resistance of the battey8 uo)by c1b6qry?
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 b.h; 9xljdgqn7; ejd( $4.0-k\Omega$ 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 parallr k p30a v6.ubz30ofl bc*f l+njjh1;sel-plate capacitor has capacitance $C_0$. If two identically sized dielectric slabs of dielectric constants $K_1$ and $K_2$ are inserted as shown in Fig. 19–64, what is the new capacitance? [Hint: treat this as two capacitors in combination.]

  For the circuit shown inx:qy)* t w-fhrdlf o- juqs*61(Fig. Below), determine
(a) the current through the 14-V battery $I_1$ =    $ \times10^{-5 }\;A$ ----待选择----downupward 
(b) the potential difference between points a and b, $V_a-V_b$ =    V

  A solar cell, 3.0 cm square, has an output of 350 mA at 0.80 V when exposed t.v/xfh v e6e8eo full sunlight. A solar panel that delivers close to 1.0 A of current ev8ev /.fxh 6eat 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 outpn, dns ed 9x .e2(guqyo6(5qi iyr-5qaut 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 (Fig. oejb0prlur:5. h* fv) Below b). This neon lamp has a 0.: 5jr*vul)h ofbper 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 ttp 47y ryhqx97ylodd20st.,w he $20-\Omega$ 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)z y(vd r2n1+ksnv*h0x, the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistancki-h)xv (0d gse 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 cif2406 p51hx qt c qfy3p-slnman be connected as shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading, a3x lhnpf-2 pm4 qiy0fcqs1 t65nd I is the ammeter 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 ra /ppg e,l7nniq.- z7hnted at 2.5 W and 3.0 V is operated by a 9.0-V battery. To light the bulb at its ratein- nqp /h,z pl.gen77d voltage and power, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$