Explain why birds can sit on power xz5cwp709h 6etgbze3 ; 0/ cpzq-jei rlines safely, whereas leaning a metal ladder up against a power line to f6ze/7ppje 3-z5t heq0 bg;rzw9x c0icetch a stuck kite is extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree lighs6zz v6dt 0)7fxnih5e ts connected in paralle7n 5vf60t zxh6)dsz iel versus those connected in series.

If all you have is a i6oez iw h0gfa;yq41l7: h)cy120-V line, would it be possible to light several 6-V lamps )1 6hogwql7:;yia4 ehc 0i fzywithout burning them out? How?

Two lightbulbs of res,g./e ku r.locgu;rw ws:nk wbh- h1(,istance $R_1$ 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 these c))ybf wx*m;a +e3cc dy9ruyt5onnected in series or parallel? How do you kno5f;d3yrtbc+ymwe* y9 cu)x a) w?

With two identical lightb- gxc)snn32knulbs and two identical batteries, how would you arrange the bulbs and batteries in a circuit to get the maximum possible total power out? (Assume the batteries have negligible intexgknnc3-2)sn rnal resistance.)

If two identical resistors are connected in c g6s ul8zqx-t(d8t:oseries to a battery, does the battery have to supply more power or less po(lxt8 c :-zq8to g6usdwer than when only one of the resistors is connected? Explain.

You have a single 60-W bulilh tiz+5tzo ezm en5/m,q)1o( zr8o2b on in your room. How does the overall resistance of your room’srommeo 5/q8to i(t,2zi+ze h1z 5l )nz electric circuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as in Fig. Below), does the sg +gg3qxtz3k .ign (or directiog.z3g k+g qxt3n) of a battery’s emf depend on the direction of current through the battery? What about the terminal voltage?

  Given the circuit shown in Fig. 19–36, use the words “increases,” “decreases,” 5bvbe w c)(4oqmcin+dr1 84um apye/5o5)m 15b mqobad4 nepci8/e4( yw+ucvrr “stays the same” to complete 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 seriesgcw 61an )lr*w+dvx c8? For what use are they connected in parallel? Does it matter if the batteries are nearly idecnwg* 8 )1cxw r6d+lavntical or not in either case?

Can the terminal voltage of a battery ever exceed its emfz ,p6sxwv culgev**) 9dlrrb 2k9xb31? Explain.

Explain in detail how you could measure thg; v,ifx4okk4e internal resistance of a battery.

Compare and discuss the formulas for resistorkdkk 9msj vf/d)x/6y .s and for capacitors when connected in series and in6dvmk/jk)d9kxy /sf . parallel.

Suppose that three identical capacitors are mrj9-hrq4 a1 hconnected to a battery. Will they store more energy if connected in seriesh1rq-94 rah jm or in parallel?

Why is it more dangerous to turn on an electric appliance when you aheb7 r0lls-x4 hqpbx k *p9b-0tt*jt5re standing outside in bare feet than whenq bbx4xrh-5l p tbs*7jlh0p0t* k9t-e you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) micropu /2bew.4jnpb bl ( 8(/ gqdq4ybcs7ddhone. 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 frequency as the sounb 8d cy2p4e7nq/ wl(gsu.q( bb/djd b4d wave is produced.

Design a circuit in which two different switches of the type shown in (Fig. Belon:tt m)lpoz1ng9y0/4-s 4wv4vk oaxr w) can be used to operate the same lightbulb frogoptlw k9z1tsvr 4 n -onv4/4) :ymx0am opposite sides of a room.

In an RC circuit, current flows frov cl2,n oa3c4gm the battery until the capacitor is completely charged. Is the total energy supplied by the battery eo2vn3l ca,g c4qual to the total energy stored by the capacitor? If not, where does the extra energy go?

What is the main differencez op+mhtlr) q1nc;+r7 between an analog voltmeter and an analog ammeter?

What would happen if you mistakenly used aoy;; v -oie3xon ammeter where you needed to use a voltmeo-e;o3ivo ;y xter?

Explain why an ideal ammeter would have zero resistance and ezps 9ua ,dy1 rl0v53can ideal voltmeter infinite resistadvu l9p10e5z, yar3 csnce.

A voltmeter connected across a resisto g w+-lt)vr.i/x-xwzrr always reads less than the actual voltage across the resist w +z r/-it-rvx)wgl.xor when the meter is not present. Explain.

A small battery-operhj98yri(z.m 26 pxcj sj :xmz*ated flashlight 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, i jj zsm6h( 8m*j29zxpr:yc. xit registers 1.5 V. How would you explain this?

  Calculate the terminal voltage for a battery with an interl3 0+nuasx w39ufhx* cnal 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 resistktx (v8l8sw-t ance 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 havejcrmuz-62pr hjzgqg(hu.7x297 0nf z 0y su b; 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 have9n3/b)ww* c agjwb3yb 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 wz6pbksfglw, 5)v. )r kw 5l/c$12.0\,V$ 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 smb8; psj33. x 8rpbvaoeries 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 vqbmn2r34f b/ b6h7a j-a i6ajin parallel 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 electric circuit reveals h nj1ip ur1( dmzr5)13bc7pex 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 (Figjmp xqj*(1kq 3. Below). Answer qualitatively: j*jm13p q (kqx
(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 ofpzqur-v;- 0k w)o i6z mkl :51hp5gk4:hfflf z the circuit connected to the battery in (Fig. Below)? Each resistance has-;4rqwpf56: fvkzzk5 h):g-luipm o flhk 1z 0 $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as sh 7s2ej i-qlbk9own in (Fig. Below). Qualitaj2 kb-iq97sle tively, what happens to
(a) the voltage drop across each of these resistors, $V_{left}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0  $V_{right}$  ----待选择----decreaseincrease0 
(b) the current flow through each, $I_{left}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0  $I_{right}$  ----待选择----decreaseincrease0 
(c) the terminal voltage of the battery, when the switch S is opened, after having been closed for a long time? terminal voltage  ----待选择----decreaseincrease0 
(d) If the emf of the battery is 15.0 V, what is its terminal voltage when the switch is closed if the internal resistance is $0.50\Omega$ and $R\,=\,5.5\Omega$?
$V_{terminal\,closed}$    V
(e) What is the terminal voltage when the switch is open? $V_{terminal\,closed}$    V

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

  Calculate the current in the circuit of (Fig. :0 *eukcyw1-0rlm qln Below) and show that the sum of all the voltage changes around the cukylc 0mrn01lw-q e *:ircuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$    V

  Determine the terminal voltage of each battery in (Fig. Below). 1tc+9 rj b2zrl16o :zie8V battery    V 12V battery    V

  (a) What is the potential difference between points a and d in (Fig. *pq:*ac 1o)b 3/hm1is xgpj-8atgfngBelow a) (same cir* t abf xc:p)g m118-g 3iqahpn/jg*oscuit as Fig. Below b, ), $V_{ad}$    V
(b) what is the terminal voltage of each battery?
80V battery    V
45V battery    V

a
b

  For the circuit shown in (Fig. Below), find the potential diffkely8sfu- s++erence between points a and b. Each resistor ha ye-k su+ls8+fs $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directions of the currents throug+qknsjsq u)5+ h $R_1$ 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 an internal resista6cwl 14u0ro -znfklu6nce $r\,=\,1.2\Omega$.
$I_1$ $\approx$    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 directiokqu/e 57lpw/67xd 8xkrx b- 6facrq0r ns of the currents in each resistor shown in (Fig. Below). The battecqfx e p-kq0 7wbx5r8ulr/a7 6xk /d6rries 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 internal resi: rn-fwwdh m9,50agdostance $r\,=\,1.0\Omega$.
$I_1$ $\approx$    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 re*5lgcv9 lgcm 1sistor of Fig. 19–49.
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the curre(*-xdukv- czvp sjbq4 p0bt 2+nts $I_1$,$I_2$, 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 curren lt48jcal o j:iw),/tjmg5k5 yt $I_1$ 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:c g+ wtcy/f*z emfs of 2.00 V and 3.00 V, are connected as shown in (Fig. Below). If ecycwt /+:zfg* ach 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, 7q9wgsss-p6nt *s; sw h44s, ba500 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 tr(g)i7ve h e 8br;u8eahe whole network of (Fig. Below), calculate the voltage across ;reeghi() 8v ra87ebu each capacitor.
$V_{2.00}$    V
$V_{3.00}$    V
$V_{4.00}$    V

  The capacitance of a portion of a circuit is to be reduced from 4800 pF to 2900 i s 5q+ 3kioi+vo539q9hnnv/qc 4lxd ipFk qi9n+i +q5x3qvnl43/oo5v9iid hs c.
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 convd ) pf+szr:1 to8a8okkvr4x,structed 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 cap-ta xt2 3b 9 thky::aixup/z7sacitance of the circuit shown in (Fig. Below).

  In (Fig. Below), if yj ml:(v1l gslbq+s --$C_1=C_2=2C_3=22.6\mu F$, 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 c u8u*u0qsu p0$C_1=C_2=2C_3=16.0\mu F$, 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), lets da8c j6daizt:b ;);v $V\,=\,78V$ 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 oml8(fchm 9 kh04h8gak f area A, are connected as shown in (Fig. Below).al km089k(8hch mh4f 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 hook4fb1f cl4ms9 * l l8tr;iwvj6zed across a battery. It is desired to store three times as much energy in64 c 9jvbi;lmwrlzfls4t*1f 8 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 connected in series with an unknown capacitance, and asn7y6,0t wkl dv a series combination they a 07y nv,dkw6ltre connected to a battery with an emf of 25.0 V. If the 185-pF capacitor stores 125 pC of charge on its plates, what is the unknown capacitance?    pF

  Electrocardiographs are often c c8 -,g - mrdcgwn3wfxocv+rh;q,.d/(theg e4onnected as shown in (Fig. Below). The leads are said to be capacitively coupled. A time constant of 3.0 s is typical and allows rapid changes in potential to be recorded accurg8evcq4gwn rxo( w -m,c t,rch3g. d-fed;h+/ately. 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. Belowx gj2y)z rk;9mfwjyq5 nf 4ri 5e4e7o9 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 Figf0xe-,lfs8 uw6g hxn)m ;c(bu. Below a (same as Fig. Below b) has $R\,=\,6.7k\Omega$ and $C\,=\,3.0\,\mu F$. The capacitor is at voltage $V_0$ at $t=0$. when the switch is closed. How long does it take the capacitor to discharge to 1.0% of its initial voltage?    $ \times10^{ -2}\;s$
a
b

  Two resistors and two uncharge-cc 44 otn)6x*n ucnqxmn(*bdd capacitors are arranged as shown in (Fig. Below). Then a potentialt (cnq- cco4xm**xnbd6nu 4) n 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 i ome8/xc1i8 byf the meter sensitivit8ecmb 8i1yo/x y is $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensinc)3arg (1s-v r fy a5y),3zgrzsap0q tivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an ingg+ e5o7ng c iyh4itz-8 e.bto1gs;4iternal resistance of $30\Omega$ and deflects full scale for a $50-\mu A$ current. Describe how to use this galvanometer to make
(a) an ammeter to read currents up to 30 A,    $ \times10^{-5 }\;\Omega$
(b) a voltmeter to give a full-scale deflection of 250 V.    $ \times10^{6 }\;\Omega$

  A galvanometer has a sensitivity ouyr(qy(jf;xp jm476p 4ui 0rvf $35k\Omega/V$ and internal resistance $20.0\Omega$. How could you make this into
(a) an ammeter that reads 2.0 A full scale,
   $ \times10^{-4 }\;\Omega$ in
 ----待选择----parallelseries 
(b) a voltmeter reading 1.00 V full scale?
   k$\Omega$
 ----待选择----parallelseries 

  A milliammeter reads 10 mA full scale. It consists of aa3o )8nyvgjf; $0.20-\Omega$ 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 internal5i(vqjqdv+ ir(sg3d0*3f - mna2oxi e 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 int25yf zzc n0/v b5izmp*ernal resistance 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 Example 19–oj.,qa.x dhdv v/za;415 have to be in error by lessq4 xv;ho ./d daj,z.av than 3%? $\approx$    k$\Omega$

  When the resistor R in (Fiqd10i)hc ,e9rt/: sj pfiweg.g. Below) is $35\Omega$, the high-resistance voltmeter reads 9.7 V. When R is replaced by a $9.0-k\Omega$ resistor, the voltmeter reading drops to 8.1 V. What are the emf and internal resistance of the battery?
r $\approx$    $\Omega$(retain one decimal places)
$\varepsilon$ $\approx$   V(retain one decimal places)

  Suppose that you wish to apply a 0x0ohhg:+bb p3ien)(v 12 m+anx2u btt.25-V potential difference between two points on the+xa2+ 3(b0p t1oi hhbg: ub)tnxemvn 2 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 can produce 50cb h3qj/*vl2lz7 u0cj. qvu h0 W, 100 W, or 150 W, at 120 V. Such a bulb contail *qcc u 2q00hlbzhv j/v.u37jns 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 electric outl + eu;sbwi-ip4et. Each of the wires connecting your apparatus to the 120-V source hasubs +;i-e4w pi 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 hospita7o3mcb(bemm; ls, 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 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 p mo(e7; mbmcb3atient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must a 45-V battery exx6va- i2nbg1rpend 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 2k4 x(7ybgukj 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 resi p0*50olenk cs lz)-inwe;kml 3;tn q(stance is $950\Omega$
(a) What current passes through the body when the person accidentally is connected to 110 V?   A
(b) If there is an alternative path to ground whose resistance is $45\Omega$, what current passes through the person?   A
(c) If the voltage source can produce at most 1.5 A, how much current passes through the person in case (b)? $\approx$    mA(retain three decimal places)

  A Wheatstone bridge is a type of “bridge circuit” used to make measurements of , x.3 dj3te-r njimemi*;9ofsresistance. The unknown rej;nmede3tfi*m xo- .jrs93i,sistance 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 unkns pb-95m+ve1hbssz o /own s-hv poz9/5essb1+ b mresistance 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 s6celd;)b0trso9e.ulgs6 v+eac a 1) which can be obtained by connecting four identical capacitors, each having a capacitan 1gl 0lde9c ;oa)6ss6e+ac)bruvets .ce C?

  The variable capacitance of an old radio tuner consists of four plates connec8,xhtbnnprrc 3t i4u6e.27ea ted 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. Oneteep, r82 h ucx r4.i736btann 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 fr pg3 t96/yhymdom it and 47.3 V when 2.20 A is drawn. What are the emf and internal re 6gm/ht9dpy 3ysistance 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 the12 qz(tv(i)oxhad7(o * uqnv hbla, t2of.ov3 $4.0-k\Omega$ 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-pla hzd7,,p4ssuw .flc 5jte 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. Be: (qrwwz /.-) trf h1jtrp+lnglow), 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 0ps7h*xsg prthdhs-0e88a:a4.80 V when exposed to full sunlight. A solar panel that d87r0 :s p4 h8sdg eahp*txsha-elivers close to 1.0 A of current at an emf of 120 V to an external load is needed.
How many cells will you need to create the panel?    cells
How big a panel will you need, and how should you connect the cells to one another?    $m^2$
How can you optimize the output of your solar panel?    banks of    cells in series per bank, with the banks in  ----待选择----parallelseries  always have the panel ----待选择---- pointedturned  directly at the sun。

  A power supply has a fixed output voltage of 12.0 V) 0qggk:k0-u*fdtk c o, 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 (w mzn .rpt1.(fFig. Below b). This neon lat (prw.n1.zmfmp has a threshold voltage $V_0$ for conduction, because no current flows until the neon gas in the tube is ionized by a sufficiently strong electric field. Once the threshold voltage is exceeded, the lamp has negligible resistance. The capacitor stores electrical energy, which can be released to flash the lamp. Assume that $C=0.150\mathrm{~}\mu\mathrm{F},R=2.35\times10\mathrm{~}^6\Omega,V_0=90.0\mathrm{~V}$ and Ann meter=105 V
(a) Assuming that the circuit is hooked up to the emf at time $t\,=\,0$, at what time will the light first flash?    s
(b) If the value of R is increased, will the time you found in part (a) increase or decrease?  ----待选择---- increase decrease 
(c) The flashing of the lamp is very brief. Why?
(d) Explain what happens after the lamp flashes for the first time.

a
b

  The current through twy u ,dzhp.45che $20-\Omega$ 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), the :mcij p9u4a) f$33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalent resistance of the circuit shown in (Fig. Belop3 , ejlasnx5:w)? $R_{eq}$ $\approx$    $\Omega$(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 cony5b,m05 2(hebfu6 wj -rvrttxnected as shown in (Fig. Below a) to measure a resistance R. If V is the voltmeter readinbrv th,tu5( 2-bry f0m5ewj 6xg, 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 u4z;5ncq**yh1 hjihdby a 9.0-V battery. To light the bulb at its rated voltage and powy hcud*nh5q 1izh; j4*er, a resistor R is connected in series as shown in (Fig. Below). What value should the resistor have?    $\Omega$