Explain why birds can sit on power lines safe7)roeg5 mr7velc rs-63 p2kj qly, whereas leaning a metal ladder up against a power line to fetch a stuck kite ig krmsv3)re2 6q7-lpr 5 ceo7js extremely dangerous.

Discuss the advantages and disadvantages of Christmas tree lights connecteyhz32d sl9i u ft lt.5n.45qgpgnd 9t2ql:l9 pd in parallel versus thoset i5pdz.pn9ft2yqq 4lt dh39l .ln:2 gg9usl5 connected in series.

If all you have is a 120-V line, would it be zyu ii)q v44c v*es2r: d9w3zy;b ,gyqpossible to light several 6-V lamps witho9si2*,q de wyr4vc 43g;u:izvqbzyy) ut burning them out? How?

Two lightbulbs of resn eb dfo4 p)57 qauzsm,6w: -,uilglkgqv8y3 )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 conno8 oh8ot/8h,r/c9 n ,fvr bndgected in series or parallel? How do you kn8 9n, 8c rrtob//o8g,vhfhodnow?

With two identical lightbulbs and two id. sncrh7;xn7l22 br* gacywz8entical batteries, how would you arrange the bulbs and batteries in 7g8hbazrcsw7lnr yc;2*. nx2 a circuit to get the maximum possible total power out? (Assume the batteries have negligible internal resistance.)

If two identical resimxj t39*gr2t vl3lcr8 stors are connected in series to a battery, does the battery have to supply more power or less power tha *vc3tg 3829lxjmlrt rn when only one of the resistors is connected? Explain.

You have a single 60-W bulb on in your room. How does the ov)93(pv;b/d pdqetxu*zoj2 awerall resistance of your room’s electric c 3q;wbp/d *j aotxe2dpz) (u9vircuit change when you turn on an additional 100-W bulb?

When applying Kirchhoff’s loop rule (such as iyj . e(bmd()jon Fig. Below), does the sign (or direction) of aemdo.jy (b()j 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,” “decre quuf,10h0oby ases,” or “stays the same”u 1qh0ub ofy0, 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 ot31)jj)ukv nud1qj9 series? For what use are they connected in parallel? Does it matter if the batteries are near1)ujtku3 )jnvo1 q dj9ly identical or not in either case?

Can the terminal voltage of a battery ever exceed its s8yb earl4a27 zl.1kn88 ors jv)4ooremf? Explain.

Explain in detail how you could mep)* t+uw gx1a:vy rbx9asure the internal resistance of a battery.

Compare and discuss the* hidb6j eb8n7 formulas for resistors and for capacitors when connected in 6d* nhibe87j bseries and in parallel.

Suppose that three identical capacitors are pf ,0m qb7g/5cqvrfv(i;:pafconnected to a battery. Will they store more energyiv v pf:;q0 p/amg5b7cff q,(r if connected in series or in parallel?

Why is it more dangerous to turn on an ele :h gx 1o/jevfv ,n4ige4d v:)kt::gljctric appliance when you are standing outside in bare fhk ev d1 ::ji gx/:egf vogv4tn)j:l4,eet than when you are inside wearing shoes with thick soles?

(Fig. Below) is a diagram of a capacitor (or condenser) microphone. T((u u0gaa m*rh3pa 5,f,gwlf ihe 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 fre03g5 ,(a* fawrlu fg(ihupa, mquency as the sound wave is produced.

Design a circuit in which two different switc716iutw2uk4p + zruq xhes of the type shown in (Fig. Below) cu ut261uik 4xzq7wr+ pan be used to operate the same lightbulb from opposite sides of a room.

In an RC circuit, current flown)3 gg. : 1pabkp,nwszs from the battery until the capacitor is completely charge.gpb1a):w,gp k3nn zs d. Is the total energy supplied by the battery equal to the total energy stored by the capacitor? If not, where does the extra energy go?

What is the main difference between an analog voltmeter and an analo iyydw f7 /c+6hcwb,l4g ammeter?

What would happen if you mistakenly used an ammeter where you n0tlxq;cbq n/oo+ v r8+eeded to use a voltmeten;+/8tob+v0 oxc qqrlr?

Explain why an ideal ammeter wof.htqu, 39m qku +u6rzuld have zero resistance and an ideal voltmeter infinite res3mh k6uqu+u9qfzr .t, istance.

A voltmeter connected across a resistor always reads less than the ac5j) kz mb9)-c 5mmfl8wgj awi+do(nt1tual voltage across the resistor +a)nl1 c 5(58m9d j-z) fkibgtmmjowwwhen the meter is not present. Explain.

A small battery-operated flashlight req7v txfjcq y rv+.xt:,8uires 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 would you explain thx .f,8 7x:vtrjt+yv cqis?

  Calculate the terminal voltage for a battery with 3ci)e7p8x1 e2pds2nxq1lk qv 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 resistance o dis ;xzw*..abf 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-x (zyi4q.1+uo ggtf esp4 m/l 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 have iwyct,ld7bx7 (u2y * rrp7fu. 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 tq..29xd d uxvof $12.0\,V$ shows a terminal voltage of $11.8\,V$ when operating in a circuit with two lightbulbs rated at $3.0\,W$ (at $12.0\,V$) which are connected in parallel. What is the battery’s internal resistance?    $\Omega$

  Eight identical lights a thbip5or./ ef(7ia)t ioaom2v c ;g;4re connected in series across a $110-V$ line.
(a) What is the voltage across each bulb? V$\approx$    V(Round to the nearest integer)
(b) If the current is $0.50\,A$, what is the resistance of each bulb, and what is the power dissipated in each?
R $\approx$    $\Omega$(Round to the nearest integer)
P $\approx$    W(retain one decimal places)

  Eight lights are connected iwf,vq aq -g9b*n 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 $ =    $\Omega$
firaction wasted =   

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

  A close inspection of an electric cirsx.*b sgc1f j+hv1 t,mcuit 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 qualitatively:bh:2rif ( hi)n2gy) ea:ru/rb fna(bhgy)ir:heir/u2 2 )b:r
(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*im( uob3qh d1q bu(w) to the battery in (Fig. Below)? Each resw* 3bium()uq bo1(qdhistance has $R\,=\,2.8K\Omega$.   k$\Omega$(retain one decimal places)

  Three equal resistors (R) are connected to a battery as shown in 7uo9vb)lhensyi1r f7b:v ,u.(Fig. Below). Qualitatively, what happens to 9fus1n.vivub by)7ler:o 7h ,
(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 s,ud3z olu 1 u/psv.c.xum of all the voltage changes arou/ l u3c1xozvd,pu..us nd the circuit is zero.
I $\approx$    A(retain two decimal places)
$\sum$ =    V

  Determine the termin m*pth7fhr x8n 6g cr85jsm3g-al voltage of each battery in (Fig. Below). 18V battery =    V 12V battery =    V

  (a) What is the potential difference between points a om.-y2q 5lk spand d in (Fig. Below a) (same circuit as 25sl-m.qykpo Fig. Below b, ), $V_{ad}$    V
(b) what is the terminal voltage of each battery?
80V battery =    V
45V battery =    V

a
b

  For the circuit shown in (Fig. Below), find the potential difference beto b0gg)h+ 3wc7r4ejukween points a and b. Each resis4h3 gr7jo we bkg0uc)+tor has $R\,=\,75\Omega$ and each battery is 1.5 V.    V

  Determine the magnitudes and directiosg8,q4 a tk:ggn 9jpkr/srgq: jt3h4+ns of the currents through $R_1$ and $R_2$ in (Fig. Below). $I_1$    A  ----待选择----leftright  $I_2$    A  ----待选择----leftright 

  Repeat Problem 27, nonb7jg +n,.,(mcv fva0zv9+d q qzxz.nw assuming that each battery has an internal resistance $r\,=\,1.2\Omega$.
$I_1$ $\approx$    A  ----待选择----leftright (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftright  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftright  (retain two decimal places)

  Determine the magnitudes and directions of the currents in each resistor sho8ifkr;s,. f1: ga(jnxaa rv 5kwn in (Fig k. k8f;(rxif1asjnavg :5,ar. Below). The batteries have emfs of $E_1\,=\,9.0V$ and $E_2\,=\,12.0V$ and the resistors have values of $R_1\,=\,25\Omega$,$R_2\,=\,18\Omega$, and $R_3\,=\,35\Omega$
$I_1$ $\approx$    A  ----待选择----leftrightup (retain two decimal places)
$I_2$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)
$I_3$ $\approx$    A  ----待选择----leftrightup  (retain two decimal places)

  Repeat Problem 29, assjfx.9 ty wzu5yo2 -2ua6.iss v-ik2qo uming 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 resistor ) dd 5w a(s,t09;f vtv4xl.f whs-bjyvof (Fig. Below).
$2\Omega$    A
$6\Omega$    A
$8\Omega$    A
$10\Omega$    A
$12\Omega$    A

  (a) Determine the cue);luy e(vdugg*wx / ;rrents $I_1$,$I_2$, 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 currenh95 nw);mmbsrt $I_1$ 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 u1g+l8 jwnmyo uv;0y, V and 3.00 V, are connected as shown i0lug, 8y vun ;jwmo+1yn (Fig. Below). 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, 75if 6- odddc((e00 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 acrbw66ia 2f lh.abx1 p8xoss the whole network of (Fig. Below), calculate the voltage across each capacitor.l1 aibhbxwpa 28 x.6f6
$V_{2.00}$ =    V
$V_{3.00}$ =    V
$V_{4.00}$ =    V

  The capacitance of a portion of a circuit iszb1cb 6j:z)okl nm:g1ezi4-p to be reduced from 4800 pF to 2900 ngk bm cozlbz6:ei4j) 1:-1pzpF.
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 accidenr d1*s76fy-y3gytsz* gu jwe(tally 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 capacita zt3+mg5zl/7ny l0rivnce of the circuit shown in (Fig. Below).

  In (Fig. Below), if fdvv0d s0(b x6$C_1=C_2=2C_3=22.6\mu F$, 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), supp;f4kiwdb)b2(044rniaqs*k k lge3ak ose $C_1=C_2=2C_3=16.0\mu F$, 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), let13 ehgxj4k v6.u,hdac90wqwq.0ggg b $V\,=\,78V$ and $C_1=C_2=2C_3=7.2\mu F$. How much energy is stored in the capacitor network?    $ \times10^{-2 }\;J$

  A $0.40-\mu F$ and a $0.60-\mu F$ capacitor are connected in series to a 9.0-V battery. Calculate
(a) the potential difference across each capacitor,
$V_1$ =    V
$V_2$ =    V
(b) the charge on each. $Q_1$ =    $ \times10^{-6 }\;C$
(c) Repeat parts (a) and (b) assuming the two capacitors are in parallel.
$V_1$ =    V
$V_2$ =    V
$Q_1$ =    $ \times10^{-6 }\;C$
$Q_2$ =    $ \times10^{-6 }\;C$

Three conducting plates, each of area A, are c5*pnxsmv(w6 ,s0i8 f7l6zxac 6qcvr sonnected as shown in (Fig. Below).fl cv56i78c ps s mvz0wq,xrs*xn6 6(a
(a) Are the two capacitors formed connected in series or in parallel?
(b) Determine C as a function of $d_1$,$d_2$, and A. Assume $d_1+d_2$ is much less than the dimensions of the plates.

  A circuit contains a single 250-pF capacitor hooked acr1( sv*n3 )maxem2gagvoss a battery. It is desired to store three times as much energy in a combination of two capacav (*3ge2vxa s1mgmn )itors 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 connectn u,bpueq7 xz(+v:s1wed 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 its platesq p+s:,ue n1zxvu 7w(b, what is the unknown capacitance?    pF

  Electrocardiographs are often conntx 0w6j(x qhd7zt,9ty5e8lhz ected as shown in (Fig. Below). The leads are said t(yjtq5 wx6zx ,9t 08h7dzelh to be capacitively coupled. A time constant of 3.0 s is typical and allows rapid changes in potential to be recorded accurately. If $C\,=\,3.0\mu F$, what value must R have? [Hint: consider each leg as a separate circuit.]    $ \times10^{6 }\;\Omega$

  In Fig. Below a (same as Fig. Below b), the total ril:rv y: 0y3qzesistance is $15.0k\Omega$, and the battery’s emf is 24.0 V. If the time constant is measured to be $35.0\mu s$, calculate
(a) the total capacitance of the circuit    $ \times10^{-9 }\;F$
(b) the time it takes for the voltage across the resistor to reach 16.0 V after the switch is closed.    $ \times10^{-5 }\;s$

a
b

  The RC circuit of Fig. Below a (same as Fig. Below b)ej8ck0qxr 4d;u) c0be 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 unchargj7 wkjn g rk3-hte5i:-ed capacitors are arranged as shown in (Fig. Below). Then a potential difference of 24 V is applied across the combination as shtejj-7wn:g3r i k h-k5own.
(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 v.3 7mlzs4 iwfo1orss6 oltmeter on the 250-V scale if the meter sensitivity i1lmo.zsi6s4 rsfo w37s $30,000\,\Omega/V$?    $ \times10^{6 }\;\Omega$

  An ammeter has a sensit- 6x 8egic9qc sx./zqwivity of $20,000\,\Omega/V$? What current in the galvanometer produces full-scale deflection?    $\mu A$

  A galvanometer has an internal resistance o1obnyz wi/;.x f $30\Omega$ 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 sensitsrex:ij ./yx 7ttn3nqq60kh5b c/;s u ivity 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 10qsk jl7 i3w(x us-g5xnkj8)m) 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 negligible internal resistance is connectedq+a h6tpu) xv q mk1+j-lre5+d 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 resistag zahjayl:hf3m s-(j hgk 6;*.nce 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 E61s1mu6r(1 aejpjx qexample 19–15 have to be in error b6 (1 xs1emp16rajuejqy less than 3%? $\approx$    k$\Omega$

  When the resistor R in (;.br0tj )l +g slg/u0xfy-ign Fig. 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 appl t*dkulo 6 ozuizc vv*01cy2(;y a 0.25-V potential difference between two points on the human body. The ;kou 6cv( 21 dtzyco0**lu vizresistance is about $2000\Omega$, and you only have a 9.0-V battery. How can you connect up one or more resistors to produce the desired voltage?    k$\Omega$

  A three-way lightbulb can produce 50 W, 100 W, org6gqgu 3u/p ( m+jj*ol2hcga , 150 W, at 120 V. Such a bulb contains two filaments that can be connected to the 120 V individually or lhjgp aug*2c/ q+og,j3(6 mguin 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 s y88nkg7 1uhw w)bvu jjxb6).uome apparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to thehynu. j1g ux)w7 uk88)vb6 jbw 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 to patients whgs 63kz6kxp.kxdzic++a57ilo are connected to electrodes, such as an ECG. For example, suppose that the motor of a motorized bed d6kp kkcg la s+i5izzx7.x36+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 patient. $\approx$    $ \times10^{-3 }\;A$(retain three decimal places)

  How much energy must a 45-V ba to l7tcyh93 6ew bq/c*c5wn,kttery 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 o8);a2anzjzbm b-;;wk hs sv5at 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 jdw,vlw :iz nr,60 53(zq*s k1hylbljtance 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 sm,t5*o;psi h*pf 0 ycof “bridge circuit” used to make measurements of resistance. The unkn,p0 y*s*5; ipftc osmhown resistance to be measured, $R_x$, is placed in the circuit with accurately known resistances $R_1$ ,$R_2$, and $R_3$(Fig. Below). One of these, $R_3$, is a variable resistor which is adjusted so that when the switch is closed momentarily, the ammeter Ann Meter shows zero current flow.
(a) Determine $R_x$ in terms of $R_1$ ,$R_2$, and $R_3$.
(b) If a Wheatstone bridge is “balanced” when $R_1\,=\,630\Omega$,$R_2\,=\,972\Omega$, and $R_3\,=\,42.6\Omega$, what is the value of the unknown resistance?    $\Omega$

  An unknown length of plb4fzwm. rx 2j1kv2um( atinum wire 0.920 mm in diameter is placed as the unknown resistance in a Wheatstone bridge (see Problem 71;Fig. Below). Arwfb1 vrx2.mjz4m u(2k ms 1 and 2 have resistance of $38.0\Omega$ and $46.0\Omega$ respectively. Balance is achieved when $R_3$ is $3.48\Omega$ How long is the platinum wire?    m

What are the values of effective capacitance which can be obtaineb- fc a(7x:v891hd 1xaa2nkmhlu yw g*d by connecting four identicau*2ahw:(fc -nb7vhx1m lxk8 y 9adg 1al capacitors, each having a capacitance C?

  The variable capacitance of an old radio tu3(-- ).tlytkt.ue ty;oqjn42atnh sk ner consists of four plates connected together placed alternately between ty2. (;-nan-qte toty. j4u)kkhlt3s four other plates, also connected together (Fig. Below). Each plate is separated from its neighbor by 1.5 mm of air. One set of plates can move so that the area of overlap of each 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 qj+*t;sb39b v5z 2u: ofodm jgwhen 7.40 A is drawn from it and 47.3 V when 2.20 A is drawn. What are the emf and internal rsmj9ub oj 23dt5; *:+gozvbqfesistance 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 ti8xsi-3 vsb :v5sr- b8cz wn-uhe $4.0-k\Omega$ 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 capacm9sule+1 c (tjitor 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. B r1do)skswu* *elow), 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 7b+(t gdu3 .qaywmpkk1/sj g*0.80 V when exposed to full sunlight. A solar panel that delivers close to 1.0 A of current at an emf of 120 V to an external load is ne7q/gw(k+bsg 1.3yu p* dajmtkeded.
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 12.13h)/fr5 nasx t/ojng 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 tu4u0m,jh ee ljg73)wocmze f 1ap,h( rt-w6(vabe as in (Fig. Below b). This neon lamp has a threshold volt(wwlea4pjt,jcr 3muo7hfm6e) -h, ez1va(g0age $V_0$ 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 0gbaux3l6 e mvt.9 qro c)mm5+the $20-\Omega$ 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), tcyq 3j-kd- 1yolaqr2i6 iml :;he $33-\Omega$ resistor dissipates 0.50 W. What is the battery voltage? $\approx$    V(retain one decimal places)

  (a) What is the equivalep thi,g arpk/e) n2j/92k shf-nt resistance of the circuit shown in (Fig. Below)? $R_{eq}$ $\approx$    $\Omega$(retain one decimal places)
(b) What is the current in the $18-\Omega$ resistor?    A
(c) What is the current in the $12-\Omega$ resistor?    A
(d) What is the power dissipation in the $4.5-\Omega$ resistor?   W

(a) A voltmeter and an ammeter can bs 8b r53;ili(iypx4iaez b1d;e connected as shown in (Fig. Below a) to measure a resistance R. Ifpia(l1izsr b3i5y;bexi4 8 ;d V 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 ratedr-u2e1 k pk+or at 2.5 W and 3.0 V is operated by a 9.0-V battery. To light the bulb at its rated voltage and power, a resistor R is connected in series as shown orrpke k2-u1 +in (Fig. Below). What value should the resistor have?    $\Omega$