Explain why birds can sit on power lines safely, w zo:7lz9h-juzw kd1f 3v1aq-f ei 9c(vhereas leaning a metal ladder up against a powerc o 7auw9z:zfvk-dz fl-3e9v1 hqij 1( line to fetch a stuck kite is extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree lights connected dub1s-klbrbw)l.: z, in parallel versus th z1lu.-s)b:,bbwdlkr ose connected in series.

If all you have is a 120-V line, would it be possible to light seveazn) n;uy(ky dqkkn9r :4. (plral 6-V lamps without burning theukq4 p kky lrd((9)a;.nnyz:nm out? How?

Two lightbulbs of resawva,)9j+. llko jv8fistance $R_1$ 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 out4wdn 0.0cbiuk lets. Are these connected in series or parallel? Ho00i kcdnwb. 4uw do you know?

With two identical lightbulbs and two identical batteries, how wouhz(1lv+ogo. q63wzu u ld you arrange the bulbs and ba1g ol6uwzq3( ovh .z+utteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resishzevm-i vn) f(1h *2jqtors are connected in series to a battery, does the battery have to supply more power or less power than when onl hjfzev(vn q-* h1i2m)y one of the resistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the overall resistvj0cp 0j5ap0li2tv ;rance of your room’s electric circuit change when you turn on an additional 100-W bulbjvp0ap2cl jt v0r;50 i?

When applying Kirchhoff’s loop rule (such as in Fig. Below), does the sign (or dk g0 fw5z9btmj(eki+7 irection) of a battery’s emf depend on the direction of current through the battery? 9jke7bitwm5 k+0 zg f(What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “increases,” “decreases,q(pkyp9 (q.hzo (gb)t yew71ih*+ij m” or “stays the same” to (qe h9iyt(bqky m*g7iz(h+ p1) wp .ojcomplete the 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 se:i+dad 6f ej8cries? For what use are they connected in parallel? Does it matteri dd86ej:+fac if the batteries are nearly identical or not in either case?

Can the terminal voltage of a battery ever exceed its emf? Expl(ixhfwmp 1f k9*eb5+rain.

Explain in detail how you coub4, b m,efou+sld measure the internal resistance of a battery.

Compare and discuss the formulas fore;h*vd hr5+ m:b xb 6zvtmnz/) resistors and for capacitors when connected in series a5be+ )6 h:mbzvmt*/; z dhxvnrnd in parallel.

Suppose that three identicc ,*p8bm7+gq)hub xh hal capacitors are connected to a battery. Will they store more energy if c8 hb hc*)m7xpq+,hbgu onnected in series or in parallel?

Why is it more dangerous to turn on an electric appliance when you v txniwg1kh7m b m5bc-u, *ax7x6fz37are standing outside in bare feet than when you are inside wearin756hm x*vxuf17, g cka3tb-7x mnibzwg shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or conde 2kdzm,p;,veu nser) microphone. The changing air pressure in a sound wave causes one plate of the capacitor C to mokm;,pedu2v z, ve 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. Be.yr72ladb2qesilk08 f 7,z oc low) can be used to operate the same lighlz ky8 o 2 asr,q0eli7.dcf72btbulb from opposite sides of a room.

In an RC circuit, current flows from the battery 1m0tr egj s:guw6:un+ 8xj9umuntil the capacitor is completely charged. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If not, w:rnu gx+9mg 1 u:tu0jj68 meswhere does the extra energy go?

What is the main diffeybs9p )d xx.( ks/xa6mrence between an analog voltmeter and an analog ammeter?

What would happen if you mistakenly used an ammeter where you needed tz 6 ahl1xl)hj4o use a voltmeter ) z4ajlxh1hl6?

Explain why an ideal ammeter wooi/eeklztlkt;nb mox, .t hw,;+t0* 1 uld have zero resistance and an ideal voltmeter infinite resist; tk/+t;lh ,zetbnm,ixko.le t 0 o*1wance.

A voltmeter connected across a resistor always r*7qr:cfl1dsg) 2kji5sb yp 0l4fe1my eads less than the actual voltage across the resistor when the metereksby5 l17jl f*d0:c2i gq4 )rym1pfs is not present. Explain.

A small battery-operated flncpv r/0and+5ashlight requires a single 1.5-V battery. The bulb is barely glowing, but when you take the battery out and check it with a voltmeter, it registers 1.5 V. How woulrd 0vncp+a/n5d you explain this?

  Calculate the terminal voltage for a battery with an internal / (oi/ 3aqbky :)hh 5p8fke1uq1hk1ylbba ;wt 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 resistaigs15,p- p hvhnce 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 av-8r l7ydwafb67 mikp z r,.(1jen4wt $680-\Omega$, 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 ,*(xuyxtw 6hy5f;pu w 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 4v 5r:o qvq5c+h77ofqn2 xavlof $12.0\,V$ 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 acjmnmm9/tr-q ( ross 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 to akak:on 1vqrbq) (w)5 u $110-V$ 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 electric ci4cqf 9hqde+ * aksb6o5rcuit 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 re9x:mp8g :ryx 3 cogwu lmg*so/ww9 (n*sistors shown in (Fig. Below). Answer qualitatively: 9ogmx*uyms (xl w 9wpw83r /g*nocg::
(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 thnt* v+icib6 vdt) zz)o7zw70oe battery in (Fig. Belowz zvn7oovi tzt0w7+ cbd*i))6)? Each resistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown iocbr z wlu4++9n (Fig. Below). Qualitatively, what happ+ ro4bzl +wuc9ens 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 shou fd5u/;ix.ge w that the sum of all the voltage changes around the circuit is zer/ie;gu d. x5ufo.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each bat;)3(tz er tsols0lvy1tery in (Fig. Below). 18V battery    V 12V battery    V

  (a) What is the potential difference b6 tlo+uti 0 fdzmj2 c/68mgg2retween points a and d in (Fig. Below a) (same circuit as Fig. Be 6mtgli/08t 2c r6gmf oj2+zdulow 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 px7xg 1umd +x m,)m:iasefp8g+otential difference between points a and b. Each resistofg x+eia+)m:7s dxu,1mpmg 8xr has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions ofhcsbiw al0j( u /ol2,bx( 69um the currents through $R_1$ and $R_2$ in (Fig. Below). $I_1$    A  ----待选择----leftright  $I_2$    A  ----待选择----leftright 

  Repeat Problem 27, now assuming that each battery has h -rcy.iv 63q9 c9gilgan 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 fu 1yh-jt0 w3 wqsd8d bm+j))ethe currents in each resistor shown in (Fig. Below). Themq) stj1f)b38w d0e-wdyjuh+ 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, az:;,nwm d krf(t) s)yjssuming each battery has internal resistance $r\,=\,1.0\Omega$.
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Calculate the currents in each 2l2t5k *qaa uhfvpr2.resistor of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curren46oo.rkt+1o5k wppe8bv vq0jl 2 n;kxts $I_1$,$I_2$, 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 currengqrkfg22y c i8;n.ak7t $I_1$ be in (Fig. Below) if the $12-\Omega$ resistor is shorted out? Let $r\,=\,1.0\Omega$. $I_1$    A

  Suppose two batteries, with unequal emfs of 2.00 V and 3.00 r4 ugnlkd29(r0 akpxox6x0f 9V, are connected as shown in (Fig. Belowpu xk00x4rfk xg9 on2d(69arl). 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, 7500 pF, and lf18*0hnm aip $0.0100\mu F$ . What maximum and minimum capacitance can you form from these? How do you make the connection in each case?
$C_{max}$ =    $ \times10^{-8 }\;F$ in  ----待选择----parallelseries 
$C_{min}$ =    $ \times10^{-9 }\;F$ in  ----待选择----parallelseries 

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

  If 26.0 V is applied across the whole network bau;,lz a5 6mr)qj.lm of (Fig. Below), calculate the voltage across each capacitor.b6rj),lma; 5.qma zul
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of a circuit is to bez swd 7; dq+6)ao71ciyf a0lm7;g wjey reduced from 4800 pF to 2900 pF. z7c y7d01 md ;gyaf;waeq7s+oilj6w)
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 ,tfv1sq 7f66j4w.roj ur o. q..gwscx 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 capacitang;*i gmazvgc ) .bym81ce of the circuit shown in (Fig. Below).

  In (Fig. Below), if /t.u)zdtb;m4kq)l olk1 wm : p$C_1=C_2=2C_3=22.6\mu F$, 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 z ( +87qgf/0klyj odrf$C_1=C_2=2C_3=16.0\mu F$, 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), letyi,fo/w5 sq,u5w8s+ cjdww 1o $V\,=\,78V$ 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 8.+dhgd+9mz a 2mgafoA, are connected as shown in (Fig. Below). .am2 ozf9+m+ahg d8dg
(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 desv2lpcc mg6lu/ ub5y:3 ired to store three 62 :lyubccmpuv3l/5g times as much energy in a combination of two capacitors by adding a single capacitor to this one.
How would you hook it up? ----待选择----parallelseries 
what would its value be?    pF

  A 185-pF capacitor is conwk ,xh 0(9pyu)4t8s t3v mtnrqnected in series with an unknown capacitance, and as a series combination they are connected to a battery with a0t(8st y 3nmqvuw,x kth49p)rn emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often connected as shown in (Fiq*ha2 78xxb pfg. Below). The leads are said to be capacitively coupled. A time constant of 3.0 s is typical and af* aphx 8qbx27llows 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), nu 2s vp16g9hwt 1hj15*/gzvexycxs1the 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 a 3 fej:dm*f(o13 0xir:pbcu plfl i+*js 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 cf d2u63 2iinwdapacitors are arranged as shown in (Fig. Below). Then a potwi2d nf i36du2ential 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 thfu+jdg;cs.p ot8* 4 n/;xdvdo4 ojfir5*v:e ve 250-V scale if the meter sensitivity ixv cvo fndvpjdj;i5o4dto:g;.e**r s u+4f/8 s $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensitivod z9thl8gc:ke/c1 x8ity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resistance 67fspfdw.d+1mwo.lm 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 sensitivihm58myq mp (5tty 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 consisn4;nki; 0epn; xl)/uxcelgu1(uyt6 xts 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 interlbp k)gvpls18k +suqpk 5 il,q3;-wi0 nal 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 ismvf/0gko h.z6yw f9q. $63\Omega$ 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 5.5hvybb 0wzy,b3bt eshould the voltmeter of Example 19–15 have to be in error bb 3hby.05b tyze5vb,w y less than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fig. B7m l-bnl((q dzp jefvo+96 kl6elow) is $35\Omega$, the high-resistance voltmeter reads 9.7 V. When R is replaced by a $9.0-k\Omega$ resistor, the voltmeter reading drops to 8.1 V. What are the emf and internal resistance of the battery?
r $\approx$    $\Omega$(retain one decimal places)
$\varepsilon$ $\approx$   V(retain one decimal places)

  Suppose that you wish to applys k1 w:sc kjf)/nz 7l.j(axoz* a 0.25-V potential difference between two points on :/)z(sj1.ojzc w anxk7l*sfk the human body. The 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 ca.wbf1/8md cr)dgf 7rjr be0,kn produce 50 W, 100 W, or 150 W, at 120 V. Such a bulb contai1frr.jw,dc8b) kb/gm7 0r efdns two filaments that can be connected to the 120 V individually or in parallel.
(a) Describe how the connections to the two filaments are made to give each of the three wattages.
50 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
100 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
150 W output use  ----待选择---- higher-resistance filament lower-resistance filamentfilaments in parallel 
(b) What must be the resistance of each filament?
$R_{50W}$    $\Omega$
$R_{100W}$    $\Omega$

  Suppose you want to run some apparatus that is 95 m from an eb +pcoyrj-sv n//f8tk 2 yr 4o8ke0t(zlectric outlet. Each of the wires connecting your apparatus to thfk0j 4cr+y8spt(8vz/-2r ot okb/e yne 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 )lv/,yrqf6ji 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 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 fqlvj6 /) i,yrthe current through the patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must0 ly vcn5j( 7j0c+xdvqktmj;-r1*d im a 45-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 at 72 .9 .imlcjs rpb(x4kf8 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 resistqq 95z+ ds.yp 8t+foxgance 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 “j-2ukp12,+yhi )noiyh eg/ hx bridge circuit” used to make measurements of resistance. The unknown resistance to be measu yih/ o2+n1h jkyihpug )xe-2,red, $R_x$, 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 q.3.nlto6y7dz )gyyx.2 efwhin diameter is placed as the unknown r 3oy.h62fg. x)d tln wyez7.qyesistance in a 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 whic0onp(u ( gn*neh can be obtained by connecting four identicpg(u *o0(e nnnal capacitors, each having a capacitance C?

  The variable capacitance of an old ravht h8+d.hykyig90n (dio tuner consists of four plates 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 cvt.dny8yhkg hhi( 0 9+an 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. jy bnl*8vypnod )zval8 t78:.40 A is drawn from it and 47.3 V when 2.20 A is drawn. What zl8ab yp *vn87o ntly8jd:.v)are the 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 thvvvd o 4.0dm4ce $4.0-k\Omega$ 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-plaah1w29xhf 2crvh q,/fte 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 in(Fig. Bz1gdhjtz 7u4h5 c:-b(txl1* uh uoc3gelow), 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 sqf9y-wt, (jbr x2 -xferuare, has an output of 350 mA at 0.80 V when exposed to full sunlight. A solar panel that delivers close to 1. fwr r2-x-9etfybj,( x0 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 1jo2 q7f9c2/jo hpr.):cntgoc2.0 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. Belm2u0/iz3c2t 0+bohu-mx f(l km;j k xho5r;r iow a) uses a neon-filled tube as in (Fig. Below b). This neon lamp has a threshold v(hx+mhf25 k02oim r -tjc;/u umzlio;x30krboltage $V_0$ 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 the +a, t utu;7none u9p;y$20-\Omega$ 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. Beyp ) aqs+ d /fw,oevid.2nem::low), 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.0+aq7zqaa w -lb 0gue 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 anhjxo j w )ajdl-x4m33nrn5yf*l7j;u7 ammeter can be connected as shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter reading,-7l 54 h*)mxnjx ywjod;nf337juja lr 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 a 9.0-V batterym 1,fui lf*bk2jw/u, b. To light the bulb at its rated volta/ fjl2iwf,u1k,b *mubge and power, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$