Explain why birds can sit on power lines safely, whereas8 qb*/s/iqk gp leaning a metal ladder up against a power qks /gq*/ i8bpline to fetch a stuck kite is extremely dangerous.

Discuss the advantages and disadvantages of Chrl u;zi9q,.vm fistmas tree lights connected in parall;.l,uivzf m 9qel versus those connected in series.

If all you have is a 120-V line, would it be pos,8 jlzzl 2; z+: yskwamr3qebc077vz dsible to light several 6-V lamps without burninszmv7 8zeq2 z7lk0by:, dwc 3za lr;+jg them out? How?

Two lightbulbs of resistancj 7jqe)f:kxxw-( 1 woqe $R_1$ 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 os u88bk bjyv6;utlets. Are these connected in series or parabb88uk j6yv;sllel? How do you know?

With two identical lightbulbs and two identical batteries, hovjzap:24xlm0i+jhwz( 1k 6 lmw would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume the batteries mj1 pmxlv:2zj0zkaw4lh (i+ 6have negligible internal resistance.)

If two identical residp*/*yui ,f zpstors are connected in series to a battery, does the battery have to supply mo,fpdpu*y*z /i re power or less power than 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 6wn+ )jvy*syuag)5d 4cuq(yfyour room’s yw+( y4csjgf u5 6u*vaydq))nelectric circuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below), does the sign 1 l:h9l bxhl2+mz)jf d(or direction) of a battery’s emf depend on the direction of current tzbl)+dfhl9h :2xlm1 jhrough the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “increases,” *-cmz9j 8be2n*iuuus “decreases,” or “stays the same” to complete the following statements: 9umsi*u-euj8 c bz*n2
(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 batte: +vkqfq+gw k1ries connected in series? For what use are they connected in parallel? Does itvqqw1 + +kk:fg matter if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever exceed its emf? d+ j+; bak8kd yove*.l;x 1eefExplain.

Explain in detail how you could measmvbk y1j95j;.wol m0sdn:)nl ure the internal resistance of a battery.

Compare and discuss the formulas for resistors and for capacitors wnmimv -;vh/8n u1d07ij( -mvxtd;g n ihen connected in seriehnj1i0n;nx7g mvdm/- ;(v tmividu8-s and in parallel.

Suppose that three identical capacitors are connected to a batteryg(z.q ;epe,scab 6n8oct5)6v k fqnr5. Will they store more energy if connected in 6gk cpaec.,fz 8n 6or()5bvnt5;qqesseries or in parallel?

Why is it more dangerous to turn on an ele4 co nf8(v z3b*pwb-coctric appliance when you are standing outside in bare feefczcw 8 b*npvboo(3 -4t than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphonergr nt 0(2lsfp rkbb8q(-nh 99. The changing air pressure in a sound wave causes one hnpg0-9 (lr k f8 btsb9rq2(nrplate 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 different switches of the type shown in (Fig. Bel fsu.y 8.(nqpqow) can be u p..u8(f qnqyssed to operate the same lightbulb from opposite sides of a room.

In an RC circuit, current fl*4 c thx6zm8gz-kgp-ax ea;b+ows from the battery until the capacitor is completely charged. Is the total energy supplied by the battery equal to -mx6zz at be 8pa -+*c;4khggxthe total energy stored by the capacitor? If not, where does the extra energy go?

What is the main difference between an anal--xc k;df 9bpeog voltmeter and an analog ammeter?

What would happen if you mistakenly used an ammeter where you needed to use bj+ ox b1lv-1x1 v(rxqa voltb1rbl - qvxjxox+v1 (1meter?

Explain why an ideal ammeter would hanw,5mx2 . *hu0eiopuf;:s mcq ve zero resistance and an ideal voltmeter infinite eoh. u*m0,mnxc;ups 5 2if:wqresistance.

A voltmeter connected across a resistor always reads less t2z4yxhwjx n7, oe 5kq:w :2hoihan the actual voltage across the resistor when the meter is not2nko2eq,xwy5h7ih:j:w o z 4 x present. Explain.

A small battery-operated flashlight requireszy aqz3l7)+f6 xs)jil a single 1.5-V battery. The bulb is barely glowing, but when you take the battery out and che))l6yfq3+zxzsji7la ck it with a voltmeter, it registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a batteray-(-fk bres wp7*g v:y with an internal resistance of $0.900\Omega$ and an emf of $8.50\,V$ when the battery is connected in series with
(a) an $81.0-\Omega$ resistor,    V
(b) an $810-\Omega$ resistor.    V

  Four $1.5-V$ cells are connected in series to a $12-\Omega$ lightbulb. If the resulting current is $0.45\,A$, what is the internal resistance of each cell, assuming they are identical and neglecting the wires?    $\Omega$

  What is the internal res9ncdy7g vhl;do; 05/jz fvp1distance 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 havkln63s9nl o *hj yqcm4wkq4,-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 hav31 jxermqayo,*hn)agm t1 )1p e a $6.0-V$ battery and you wish to apply a voltage of only $4.0\,V$. Given an unlimited supply of $1.0-\Omega$ resistors, how could you connect them so as to make a “voltage divider” that produces a $4.0-V$ output for a $6.0-V$ input?

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

  A battery with an emf of/cz mgcsobf;( ruz3s; l: z9h1 $12.0\,V$ 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 83q.x wilgnn, 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 parallelvo0n3c* i l2/f:iy3 rz wfs5jl to a $110-V$ source by two long leads of total resistance $1.6-\Omega$. If $240\,mA$ flows through each bulb, what is the resistance of each, and what fraction of the total power is wasted in the leads?$V_R $    $\Omega$   

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

  A close inspection of an eq8iwda7ut-4 bro 11wt ji 3,uxlectric 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. Below). Answer f7k a04lj lln:qualitatively: ljkfl4n a07l:
(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 resistanc0qdnf6e9,uf c e of the circuit connected to the battery in (Fig. Below)? Each residcfnu0q fe,9 6stance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to (7wid+pq 7e-eks fz0n a battery as shown in (Fig. Below). Qualitatively, what ha-kewqn f0 (7ipdse+z 7ppens 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) and show that the sum of albjd2*o +i-8;3nuofneafi- rb it y5)kl the voltage t on2a-*j-d ryfu5f;8i n)kio i+e3b bchanges around the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of e)eczps7kh u7-li e22 j-jgq m6ach battery in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential difference bet6izlqby*l* 9a3zxuo80f)d boween points a and d in (Fig. Below a) (same circuit as Fig. Below bl0)*9 bb z3odl*qya6fzo u8xi, ), $V_{ad}$    V
(b) what is the terminal voltage of each battery?
80V battery    V
45V battery    V

a
b

  For the circuit shown in (0prol 1ktj3a-.vz h/ ; ihayf/Fig. Below), find the potential difference between points a and b. Eachi a0/lf;3 /hakhtj ov1pzyr-. resistor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of t3/wttsp/ b*/bd zxp8rhe currents through $R_1$ and $R_2$ in (Fig. Below). $I_1$    A  ----待选择----leftright  $I_2$    A  ----待选择----leftright 

  Repeat Problem 27, now assuming that each battery h1r 4nj6ha kr,yas 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 directio a(6ycn86 cq28/d cp zn.rhyao0jhb(o ns of the currents in each resistor shown in (Fig. Below). Theha6 y0n(o q( d6nc/ bc.prjacz8y2h8o 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 has int9ujn l-(ox+axh+ g x0xernal resistance $r\,=\,1.0\Omega$.
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Calculate the currents in each resistor of Fig. 19–a uvd2f b)45 k*p)mtsb49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the current v1unaktvh26x, wz8 1thj5 bd)vj )p9is $I_1$,$I_2$, 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 5kzna.h bthjej00 e -l 2 wqd3yrg-+4w$I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, witb y,s et/w(.th a0.7q3gcnncz h unequal emfs of 2.00 V and 3.00 V, are connected as shown in (Fig. Below). If each internal resistanceqya.(z,3t/bce.7w 0snntc hg 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, 08cwnf9 k:lbgmjoj wa 0w .p/97500 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 wh/j co)xb hp xx)g22*ivdzs)j2ole network of (Fig. Below), calculate the voltage across each cvz*px ghd)jsc22)2 ji/)x xboapacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of w.uga1f5 pwbt207vtpa circuit is to be reduced from 4800 pF to 2900 pF. tw 0v w.upt51b 7gpa2f
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 wavus)mgzu7l1 5s accidentally constructed using a $5.0-\mu F$ capacitor instead of the required $16-\mu F$ value. Without removing the $5.0-\mu F$ capacitor, what can a technician add to correct this circuit?    $\mu F$ conneected in  ----待选择----parallelseries 

Determine the equivalent capacitance of the circuit shown in (Fig. Bee4v +mo l:s bk (adka2wkfrir4ul2 5-4low).

  In (Fig. Below), if x.b;7 ejddpv c/ky zr.-jzz/6$C_1=C_2=2C_3=22.6\mu F$, 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), supj(d(3 pu0tibk.pb6 jp pose $C_1=C_2=2C_3=16.0\mu F$, 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), lety9) 2* xvynz5)(umjikqxwuv8 $V\,=\,78V$ 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 shx57i0u du2;hwr;rgj q own in (Fig. Below). qd2h5uj ;rw i07urx;g
(a) Are the two capacitors formed connected in series or in parallel?
(b) Determine C as a function of $d_1$,$d_2$, and A. Assume $d_1+d_2$ is much less than the dimensions of the plates.

  A circuit contains a single 250-pF capacitor hooked across a battery. It is dem 1p43egl2vppaa *0mssired to store three times as much energy in a combination of two capacitors by adding a single capacitor to this one. pp0a pm342v*al1e smg
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is conn,qk5cte*m6 vu aoql db u7k+3-ected 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 the 185-pF capacitor stores 125 pC of charge on *63ov5u7dlb, qe t-kquckam+its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often connected as show-tms0a;qcesvs- - it :n 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 poea-0ss: ;mqstv--ctitential 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 tajq kz3j, :m0uotal 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 ai(q 90n6elynlmzn f:tt 4.gw. (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 ar8we3h f/t 10o2at n u/m2oysuoe arranged as shown in (Fig. Below). Then a potential difference of 24 V is applied/3fwo8tu2t/ye2uhm0n o oas1 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 tc- 4c(cvpuovwmcitxo 54.,) che 250-V scale if the meter sensitivity t5cc4vcip.m, oc()uvwc x-4ois $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivity of z*lx kru5j;q 7yus1v(nyw5q3 $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resista-om ys*-we d/tnce 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 aklp . uwr:reu,ud(dfg r 1139j sensitivity 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 rjeqp l.l,, o.on vp/5u2,glqzxtv-; mA full scale. 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 negl cc3-0cq(aj-j,ahxd kb mv 70qigible 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 res5,se16t jt joydo1ypk6 m9 te3istance 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 thh6h8hr ,an* ii6abl*ae voltmeter of Example 19–15 have to be in errih,*r8ah nb*6 hl6aiaor by less than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. Below) is wv.bj)4 91v0dhw ryp8 og0n ct$35\Omega$, 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 betweghs pkly15et6h5z +a yu 22na/en two points on the human body. The resistance is ab+ a1tehh 5sgly6z5any/k 2p2uout $2000\Omega$, and you only have a 9.0-V battery. How can you connect up one or more resistors to produce the desired voltage?    k$\Omega$

  A three-way lightbulb can produce 50 W, 100 W, or 150 W, at 120 q2l3:yw-phgp *yk,qmV. Such a bulb contains two filaments that can be connected to the 120 gqp*y-pkqhw lmy2 3 ,: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 kd;)jl)ijsum 7 b6.jak5 c- yooutlet. Each of the wires connecting your apparatus to the 120-V source has a resistance per unit lenjj)7k.kis5oad ;)c- jy6 lubmgth 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 abe8kwxv b7p/*o q25i hazard 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 not there in the first place). If a nurse touches the bed and the patient at the same timi2 qp k* 5xavoe/wb8b7e, 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 expeezg)a0)-n -spigj+ng nd 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 des9dk * rf6mnp/qigned to operate at 72 beats/min using a $7.5-\mu F$ capacitor in a simple RC circuit. What value of resistance should be used if the pacemaker is to fire (capacitor discharge) when the voltage reaches 63% of maximum?    $ \times10^{-5 }\;\Omega$

  Suppose that a person’s body resis ype,z.jf;wl i1,p xex*gjr3)tance 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 ci- ob/vjf nbjdd 3pkd1)lu7 m3:qy0p7 ircuit” used to make measurements of resistance. The unknown resi/1ykjn3:pjm b-vofi3 7 dup7q d0) dblstance 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 iwe grlr :t;.-es placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arms 1 and 2 havete:-r.rw e;gl 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 obtac.,*o6lq/jey6sg kx ;dfymddd ;mp*h5 v-h.fined by connecting four identic;-lm/pdddhv dxegm.o*q*,.5 j6yff;s 6 hck yal capacitors, each having a capacitance C?

  The variable capacitance of an old radio tuner consists of four platesa;wcuhc j:lf90- :r pqh8b xyo9;x8pz connected together placed alternately between four other plates, also connected together (Fig. Below). Each plate is separated from its neighboj0r8;:c89b-q pu9f pwozxxhha: ; lcyr 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 whz+ pnhi*2cievf) 8 o )ncxk1k5h(pe5 sen 2.20 A is drawn. What are the emf and internal resistance of tc8ihx2p)1k(5 snpih5 eez cokf n+ v*)he 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 1 cfvbr+ /j;g6xtl )ibthe $4.0-k\Omega$ 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 ckat- ph( 3hhkos hq,/o ikf;z8zv4+z;apacitor 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 ilz 8n m+mxb s,0cer/fk(c-y -on(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 vj1r c(mrtqd; tq94kd; n b+8eto full sunlight. A solar panel that delivers close to 1.0kt rd1v4qn 9j; +(rcdtbe8mq; 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 1f0zwr).pk5w v0;dy7yu t3a bl 2.0 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 (Figr6qhimqp:/) n n-uzw+ :g; qpo h2-oqz. Below b). This neon lamp has a thr qhn : -hzqirpq)z-p;o /qgnu+26:womeshold 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 thewqv410 -plj jljs nzl,6*4rcl $20-\Omega$ 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),fbx hp*r862+voa+hg0w 7fc ut45gbdt the $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance of the circuit sg*/yp*zuh ;g chown 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. Below a) co7f uck/4yt*xj2vdfyzh;;; to measure a resistance R. If fx; k7c/;cf4o zv*2y;huydjtV is the voltmeter reading, and 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 rated at 2.5 W and 3.0 V is operated by abml i4t .z2on9 9.0-V battery. To light the bulb at its rated voltage and power, a resistor R is connt24. m9zblno iected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$