If two points are at the same potential, does this mean that no work is done in1d lzx+ffn0s3 moving a test charge from one point to the other? Does this imply that no force need be exerted?f0+lnzd1s3 xf Explain.

If a negative charge is initially at rest9m0 j3fx*1faees.aa j in an electric field, will it move toward a region*jafe9mfja3a1 sex.0 of higher potential or lower potential? What about a positive charge? How does the potential energy of the charge change in each instance?

State clearly the difference (a) between electric pot6 yt fnsf20/ ah3odnb.kgo 7e6ential and electric field, (b) between electric potential and electricgyo ko7n6se fbhatf36dn ./ 02 potential energy.

An electron is accelerated by a potential difference of, say,7fv jl3sao/otd 9dl ), 0.10 V. How much greater would its final speed be if it is accelerated with four timej ,vaodo9sd/f3t7l) l s as much voltage? Explain.

Is there a point alo:ezbcr8 rsexjm7+1jhrga3 )0t i o60e ng the line joining two equal positive charges where the electric f:z x)8rt+j s eb31j0rgcre aemio06 h7ield is zero? Where the electric potential is zero? Explain.

Can a particle ever move from a regionkwydy gb0l4t d*.5w gn-ya j- yq9+yk( of low electric potential to one of high potential and yet have its electric potent4yk a- bkdylgw j nwgy0dy *-(q.59+tyial energy decrease? Explain.

Compare the kinetic energy gainedykt3qkj h+r. 3 by a proton $(q=+e)$ to the energy gained by an alpha particle $(q=+2e)$ accelerated by the same voltage $V$.

If $V\,=\,0$ at a point in space, must $\vec{E}\,=0$ there? If $\vec{E}\,=0$ at some point, must $V\,=\,0$ at that point? Explain. Give examples for each.

Can two equipotential)uqp gc:mi r25 lines cross? Explain.

Draw in a few equipotent c jky*74r9:a4o2r.hmbjnoxe ial lines in Fig. 16 – 31b.

What can you say about thcv;hegs ,o*1-zos xlk.1:s a xe electric field in a region of space that has the same potential thro c-hgszox1v , aexsl*.1;ko s:ughout?

A satellite orbits the Earth alocug 19fjv fo.)ng a gravitational equipotential line. What shape must thg fu1jf)vo. 9ce orbit be?

When dealing with practical devices, we often take the ground (the Earth) to -db bp dd;;o)ybe 0 V. If, instead, bdb);d;dpy-o we said the ground was how would this affect (a) the potential V, and (b) the electric field E, at other points?

When a battery is connected to a capacitor, why do the qcpw 86m:(fzd two plates acquire charges(q cfzp:mw6 d8 of the same magnitude? Will this be true if the two conductors are different sizes or shapes?

We have seen that the capacit r9 sggg9mkwbu4 1uo4.w,nev/ance C depends on the size, shape, and position of the two conductors, as well as on the dielectric constant K. What then disbm9 ukwvn, o4 .e9wg/ug1rg4d we mean when we said that C is a constant in Eq. 17 – 7?

  How much work does the electric field do in moving a*v.(5tz 0ep cc 5wsouk $-7.7\mu C$ charge from ground to a point whose potential is $+55V$ higher?    $ \times10^{-4 }\,J$

  How much work does the electric field do in mowv hmhwc .(lyj :z1ao3x-+cm +ving a proton from a point with a potent y.(vz m:c-+o+m w1h3cwjlha xial of $+125V$ to a point where it is $-55V$ Express your answer both in joules and electron volts.
   $ \times10^{-17 }\,J$
   eV

  How much kinetic energy will an electron gain (in joules and eV) if it accel-mhp-o6*z w c*v)wvnberates through a potentiw*v zbn6wvh -cop)-*m al difference of 23,000 V in a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires cnchkp 2:r* 3wr4cd 6q9iy76m m/bota$7.45 \times10^{ -16}\,J$ of kinetic energy when it is accelerated by an electric field from plate A to plate B. What is the potential difference between the plates, and which plate is at the higher potential?
   V
plate ----待选择----AB 

  How strong is the electric field between two parallel plates f 1iyls 65vyp15.8 mm apart if the potential difference b5py6yvlf 1si 1etween them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field of*,m jqpp(/; o6h1 gzz;eyfzf l $640V/m$ is desired between two parallel plates 11.0 mm apart. How large a voltage should be applied?    V

  The electric field between two paralle ; mi5yli89wnmo ,ls4a 5tob0ml plates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field between t b,j:-a2oozzq wo parallel plates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is nejr 2s nno)+kqfsby6( )tm*dr o1*k-wmeded to give a helium nucleus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 200-V power supply, are sep ,mf xu1c rzv1fjk+ m0g4mm(9earated by an air ga vme,c m (kz19xjrg4 mu+f01mfp. How small can the gap be if the air is not to become conducting by exceeding its breakdown value of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an external fow6d;d grdlmdq/+2w4v- q ,zwwrce to move a $-8.50\mu C$ charge from point a to point b is $15.0 \times10^{ -4}\;J$. If the charge was started from rest and had $ 4.82\times10^{ -4}\;J$ of kinetic energy when it reached point b, what must be the potential difference between a and b?    V

  What is the speed of an ell6 avslwt( bv4hc th7h m+2e*;ectron with kinetic energy
(a) 750-eV,    $ \times10^{7 }\;m/s$
(b) 3.2-keV?    $ \times10^{7 }\;m/s$

  What is the speed of a proton whose kinetic enh5 h.ziyr6f0v1 )tbdn1ppvch . poi89ergy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (which is a hevw) t5jd9my zbpam8t4 l *oni+gf/;6b lium nucleus, $Q=+2e$, $m\,=\,6.64\times10^{-27 }\,kg$) is emitted in a radioactive decay with $_{KE}$ = $5.53MeV$ What is its speed?    $ \times10^{7}\,m/s$

  What is the electric ac135k 6yfuaopg k5,vpotential 15.0 cm from a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creatsac809troq ;pes an electric potential of $+125V$ at a distance of 15 cm. What is Q?    $ \times10^{-9 }\,C$

  A $+35\mu C$ point charge is placed 32 cm from an identical $+35\mu C$ charge. How much work would be required to move a $+0.50\mu C$ test charge from a point midway between them to a point 12 cm closer to either of the charges?    J

Draw a conductor in the shape of a football. This c1 p;uzmp2u9hcbj8o 2 he6rgloi c4w*2onductor carries a net negative chargpcjhulu2wio r c; o6821z*42h9mb pege, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potential a qqeh,mho+- :98sb s0 )re; pyxpwqx/wdistance of $ 2.5\times10^{-15 }\,m$ away from a proton?    $ \times10^{ 5}\,V$
(b) What is the electric potential energy of a system that consists of two protons $2.5 \times10^{-15 }\,m$ apart — as might occur inside a typical nucleus?    $ \times10^{ -14}\,J$

Three point charges are arranged at the corne ps x+sz,tkksz e 8l5j,qze38*rs of a square of side L as shown in Fig. 17–25. What is the potential at the fourth corner (point A), z88ek ,xtz3j,kqssz* +le5p staking $V\,=\,0$ at a great distance?

  An electron starts from rest 32.5 cm from a fig: ,exbzrnei8 p(gf13xed point charge with $Q\,=\,-0.125\mu C$. How fast will the electron be moving when it is very far away?    $ \times10^{7 }\,m/s$

  Two identical $+9.5\mu C$ point charges are initially 3.5 cm from each other. If they are released at the same instant from rest, how fast will each be moving when they are very far away from each other? Assume they have identical masses of 1.0 mg.    m/s

  Two point charges, $3.0\mu C$ and $-2.0\mu C$ are placed 5.0 cm apart on the x axis. At what points along the x axis is
(a) the electric field zero    cm leftof $q_2$
(b) the potential zero? Let $V\,=\,0$ at $r\,=\,\propto$.

  How much work must be done to bring three electrons from a g gz (3e5 orei;2zppbw2reat distance apart 22erpi ;bz(5 zg3op weto $1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is 72 cm north x7aei.q z n41aof a $-3.8\mu C$ point charge, and point b which is 88 cm west of the charge (Fig. 17–26). Determine
(a) $V_{ba}=V_b-V_a$    V
(b) $\vec{E}_b-\vec{E}_a$ (magnitude and direction).
   V/m
   $^{\circ}\,$

  How much voltage must : )ha hls2,h ; l6ethm5zd4zhmbe used to accelerate a proton (radius $1.2 \times10^{-15 }\,m$) so that it has sufficient energy to just penetrate a silicon nucleus? A silicon nucleus has a charge of $+14e$, and its radius is about $ 3.6\times10^{-15 }\,m$. Assume the potential is that for point charges.    $ \times10^{6 }\,V$

Two equal but opposite charges are separated by aul3 6mdjg llh87 uon8 5vep/9r distance d, as shown in Fig. 17–27. Determine a form8 ldrl 8vnjl67up heo/m3gu95 ula for $V_{BA}\,=\,V_B-V_A$ for points B and A on the line between the charges.

  In the Bohr model of the hydrogen atom, umm)rby6 :nx4 an electron orbits a proton (the nucleus) in a circular orbit of radius xmmyunr:) b46 $ 0.53\times10^{-10 }\,m$.
(a) What is the electric potential at the electron’s orbit due to the proton?    V(Round to the nearest integer)
(b) What is the kinetic energy of the electron?
   $ \times10^{ -18}\,J$
   eV
(c) What is the total energy of the electron in its orbit?    $ \times10^{-18 }\,J$ $\approx$    eV(Round to the nearest integer)
(d) What is the ionization energy — that is, the energy required to remove the electron from the atom and take it to $r\,=\,\propto$, at rest? Express the results of parts b, c and d in joules and eV.   $ \times10^{-18 }\,J$    eV(Round to the nearest integer)

  An electron and a pro :h.ui n7yau8iton are $ 0.53\times10^{ -10}\,m$. apart. What is their dipole moment if they are at rest?    $ \times10^{-30 }\,C\cdot\,m$

  Calculate the electric potential due ey2rkm 0 -e e-vt8xsj2ikfdab; l,*q;2b wr2qto a dipole whose dipole moment is $ 4.8\times10^{-30 }\,C\cdot m$ at a point $1.1 \times10^{ -9}\,m$ away if this point is
(a) along the axis of the dipole nearer the positive charge;    V
(b) 45° above the axis but nearer the positive charge;    V
(c) $45^{\circ}\,$ above the axis but nearer the negative charge.    V

  The dipole moment, considered as a vector,z dc3z65ef0 .xxr)y92+l jc8g alfnmb points from the negative to the positive charge. The water molecule, Fig. 17–28, has a dipole moment which can be considere e6cc fjm xl3yz.flnxzr9bda2 0g8 )5+d as the vector sum of the two dipole moments, $\vec{P}_1$ and $\vec{P}_2$as shown. The distance between each H and the O is about $ 0.96\times10^{ -10}\,m$. The lines joining the center of the O atom with each H atom make an angle of $104^{\circ}\,$, as shown, and the net dipole moment has been measured to be $p\,=\,6.1 \times10^{-30 }\,C\cdot m$ Determine the charge q on each H atom.    $ \times10^{ -20}\,C$

  The two plates of a capacitor qdb bc8r**ow kr./dg 11lv3k jhold $+2500\mu C$ and $-2500\mu C$ of charge, respectively, when the potential difference is 850 V. What is the capacitance?    $ \times10^{-6 }\,F$

  The two plates of a capacitor5p(xivg9e :ez hold $+2500\mu C$ and $-2500\mu C$ of charge, respectively, when the potential difference is 850 V. What is the capacitance?    $ \times10^{-6 }\,F$

  A 9500-pF capacitor holds plus and minus c- y rr/g:wj(zvzm*t 0kharges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference between two short sections of parallel wire in a)p8 sxatom,:g9o zc :sir is 120 V. They carry equal and opposite charge of magnitude a:zc9) os:tmoxg, p s895 pC. What is the capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows from each terminal of a 12.0-V battery wheno wrg0qk9kg 0m)+ftx( it is connected to gk) qm0g x0(rf+ot kw9a $7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired. What area muy ksb3.xwzg:7st the plates have if they are to be separatx :.kwsyzg3b7 ed by a 2.2-mm air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacin j zz).8dl(eltor increases by $18\mu C$ when the voltage across it increases from 97 V to 121 V. What is the capacitance of the capacitor?    $ \times10^{ -7}\,F$

  An electric field of 80y on1dz-7kkr9tkil $8.5 \times10^{ 5}\,V/m$ is desired between two parallel plates, each of area $35\,cm^2$ and separated by 2.45 mm of air. What charge must be on each plate?    $ \times10^{ -8}\,C$

  If a capacitor has opposite -u8ca +i r dgo/y/m2du$5.2\mu C$ charges on the plates, and an electric field of 2.0 $2.0\,kV/mm$ is desired between the plates, what must each plate’s area be?   $m^2$

  How strong is the el-0bz uxg t i xrp1c12toqfrwou/y.* )-ectric field between the plates of a $0.80-\mu F$ air-gap capacitor if they are 2.0 mm apart and each has a charge of $72\mu C$ ?    $ \times10^{4 }\,V/m$

  A capacitor is charged by a 125-V battery (Fig. 17–29a) and then is disco 7;cy cij,,q9/iph aefnnected fromf,e ,h/ccipi 9aq7;yj the battery. When this capacitor $(C_1)$ is then connected (Fig. 17–29b) to a second (initially uncharged) capacitor, $C_2$, the final voltage on each capacitor is 15 V. What is the value of $C_2$? [Hint: charge is conserved.]    $ \times10^{ -5}\,F$

  A $2.50-\mu F$ capacitor is charged to 857 V and a $6.8-\mu F$ capacitor is charged to 652 V. These capacitors are then disconnected from their batteries. Next the positive plates are connected to each other and the negative plates are connected to each other. What will be the potential difference across each and the charge on each? [Hint: charge is conserved.]
$V_{final}$ $\approx$   V(Round to the nearest integer)
$\begin{array}{l}
Q_{1}\\
\text { initial }
\end{array}$   $ \times10^{-3 }\,C$
$\begin{array}{l}
Q_{2}\\
\text { initial }
\end{array}$   $ \times10^{-3 }\,C$

  What is the capacitance of two square parallel u;a*d i s 3:sptxekk1ey 0u,g:plates 5.5 cm on a side that are separated by 1.8 mm of pa1ix;a k deuy3us, kgst:0:ep* raffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circular plates with a radius of 5.0 o+o .tdnle9p+7u jo.f cm separated by 3.2 mm of mic tu +ofj +7on.9.edolpa?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is conne2g1ln ltg;rry9n 0b 9ig q5.zacted to a 22-V battery. If a piece of mica is placed between the plates, how much charge nl;g09i.5zabrrl1 2 g9gn tyqwill flow from the battery?    $ \times10^{ -7}\,C$

  The electric field between the plates og;ml/z:27qd3j nznv af a paper-separated $(K=3.75)$ capacitor is $ 8.24\times10^{4 }\,V/m$. The plates are 1.95 mm apart, and the charge on each plate is $0.775\mu C$. Determine the capacitance of this capacitor and the area of each plate.
   $ \times10^{--9 }\,F$
   $m^2$

  650 V is applied to a 2200-pF capacitor. How much energy is sts2bts3ni9 - 4d5ktz-vznbat*ored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator t)- czgbnk w0-is used to shock a heart that is beating erratically. A ck g)w-z-bnt0capacitor in this device is charged to 5.0 kV and stores 1200 J of energy. What is its capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the electric field between two squa77)c 1fcyakedz mxe/6re plates, 8.0 cm on a side, separated by a 1.5-mm air gap? The charges on the plates are equal and opposite and of magnitud1mcz x/fa 7e6cke 7y)de $420\mu C$.    J

  A homemade capacitor is a-nyoj0ccpmyc/*+k2 iqw n.h8ssembled by placing two 9-in. pie pans 5 cm apart and cowohc-k j*nm8p 2 /+ 0ccqinyy.nnecting them to the opposite terminals of a 9-V battery. Estimate
(a) the capacitance,    $ \times10^{-12 }\,F$
(b) the charge on each plate,    $ \times10^{-11 }\,C$
(c) the electric field halfway between the plates,    V/m
(d) the work done by the battery to charge the plates.    $ \times10^{ -10}\,J$
(e) Which of the above values change if a dielectric is inserted?

A parallel-plate capa a19odt 5lj7ffcitor has fixed charges $+Q$ and $-Q$ The separation of the plates is then doubled.
(a) By what factor does the energy stored in the electric field change?
(b) How much work must be done in doubling the plate separation from d to 2d? The area of each plate is A.

How does the energy stored in a capacitor change if (a) the ptk,2,a8qkcnoo r bwl252t5hpotential difference is doubled, and,22b2ow kq l,tphtar8on5 5ck (b) the charge on each plate is doubled, as the capacitor remains connected to a battery?

  A $2.70-\mu F$ capacitor is charged by a 12.0-V battery. It is disconnected from the battery and then connected to an uncharged $4.00-\mu F$ capacitor (Fig. 17–29). Determine the total stored energy
(a) before the two capacitors are connected,    $ \times10^{-4 }\,J$
(b) after they are connected.    $ \times10^{-5 }\,J$
(c) What is the change in energy?    $ \times10^{-4 }\,J$

  In a given CRT, electrons are accelerated horizontally by 7.0 k 8d/ne j;q6sf9l0azsh V. They then pass through a uniform electric field E for a distance of 2.8 cm, which deflects them upward so they reach the screen top 22 cm away, 11 cm above the center. Estimatdq6zf h08e njl;9/ss ae the value of E.    $ \times10^{5 }\,V/m$

  Electrons are accelerabn2/b67z7c ss e em7mcted by 6.0 kV in a CRT. The screen is 30 cm wide and is 34 cm from the 2.6-cm-long deflection plates. Over what range must the horizontally deflecting electric field vary to sweep the beam fully across the screen? /e27n css6z7emm bbc7   $ \times10^{5 }\,V/m$ to    $ \times10^{5 }\,V/m$

  An electron starting from rest acquires8z.)ca 0z*ih+v yiv cs 6.3 keV of KE in moving from point A to poinvia+cv )z 8z.0*sy ciht B.
(a) How much KE would a proton acquire, starting from rest at B and moving to point A?    keV
(b) Determine the ratio of their speeds at the end of their respective trajectories.   

  A lightning flash transfers 4.0 C of charb1dh y(cx1em /ge and 4.2 MJ of energy to the Earth.
(a) Across what potential difference did it travel?    $ \times10^{ 6}\,V$
(b) How much water could this boil and vaporize, starting from room temperature?    kg

  There is an electric field near the Earth’s surface whose magnitude is b +enuozky9 +bg8kn6/about $150\,V/m$ How much energy is stored per cubic meter in this field?    $ \times10^{-7 }\,J/m^3$

  In a television picture tube, electrons are acexjfw.n*4) rfjw3z37pp no )r celerated by thousands of volts through a vacuum. If a television set were laid on its back, would electrons be able to move upward against the force of gravity? What potential diffpnr)7jwxfz n3j*rp) 43woef.erence, acting over a distance of 3.0 cm, would be needed to balance the downward force of gravity so that an electron would remain stationary? Assume that the electric field is uniform.    $ \times10^{ -12}\,V$

  A huge 4.0-F capacitor has enough stored energle/ us is2kd i5nb 4 pow7c9c43fg8bw)y to heat 2.5 kg of water from 21$^{\circ}\,C$ to 95$^{\circ}\,C$. What is the potential difference across the plates?    V

  An uncharged capacitor is connected to a 24.0-V battervc7;cq u a-*oa;faz/yt3j;wq y until it is fully charged, after which it is disconnected faaq7c- fyz; cjovq*t;w3a /u;rom the battery. A slab of paraffin is then inserted between the plates. What will now be the voltage between the plates?    V

  Dry air will break down if the electnz;bo5afg /sokj4 :. rric field exceeds $3.0 \times10^{6 }\,V/m$. What amount of charge can be placed on a parallel-plate capacitor if the area of each plate is $56cm^2$?    $ \times10^{-7 }\,C$

Three charges are at, v6n0g bze/kgfl/msi6h3t;pwqdq 32 the corners of an equilateral triangle (side L) as shown in Fig. 17–30. Determine the potential at the midpd/qwmz bf0l3eqg ;si3vn2 , h6/ktg6 point of each of the sides.

  A $3.4\mu C$ and a $-2.6\mu C$ charge are placed 1.6 cm apart. At what points along the line joining them is
(a) the electric field zero,    cm left of $q_2$
(b) the electric potential zero?

  A 2600-pF air-gap capacitor is connected to a 9.0-V battery. If a piece xf(gjlv)( a* bof Pyrex glass is placed between the plates, how much charge b) jx(al*gv f(will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally from rest in a television picture tubpsow k,mdlt6r 8-0/p se by a potential difference of 5500 V. It then passes between two horizontal plates 6.5 cm long and 1.s-s/6kr mw0 dt lp,op83 cm apart that have a potential difference of 250 V (Fig. 17–31). At what angle $\theta$ will the electron be traveling after it passes between the plates?    $^{\circ}\,$

A capacitor of capacitan cc c; (3abmi5bd0bx dd2x206,nsbxznce $C_1$ carries a charge $Q_0$. It is then connected directly to a second, uncharged, capacitor of capacitance $C_2$, as shown in Fig. 17–32. What charge will each carry now? What will be the potential difference across each?

  To get an idea how b3i/5u cgwmuoz* tj75qig a farad is, suppose you want to make a 1-F air-filled parallel-plate capacitor for a circuit you are building. To make it a reasonable size,g/ 3 co jtqm5*5w7uuiz suppose you limit the plate area to What would the gap have to be between the plates? Is this practically achievable?    $ \times10^{-16 }\,m$  ----待选择----YesNo 

  Near the surface of the Earth there ildb,lp; f7kig)57nn 2fwifo+s an electric field of about $150\,V/m$ which points downward. Two identical balls with mass $m\,=\,0.540kg$ are dropped from a height of 2.00 m, but one of the balls is positively charged with $q_1$ = $650\mu C$ ,and the second is negatively charged with $q_2$ = $-650\mu C$. Use conservation of energy to determine the difference in the speed of the two balls when they hit the ground. (Neglect air resistance.)    m/s

  The power supply for a puu+kxwv r:ct. l);i b4hlsed nitrogen laser has a $0.050\mu F$ capacitor with a maximum voltage rating of 30 kV.
(a) Estimate how much energy could be stored in this capacitor.    J
(b) If 12% of this stored electrical energy is converted to light energy in a pulse that is 8.0 microseconds long, what is the power of the laser pulse?    $ \times10^{5 }\,W$

  In lightning storms, the potential difference between,tcw3 :h( wdqn the Earth and the bottom of the thunderclouds can be as high as 35,000,000 V. The bottoms of the thunderclouds arw tchdn( ,3w:qe typically 1500 m above the Earth, and can have an area of $110km^2$ Modeling the Earth–cloud system as a huge capacitor, calculate
(a) the capacitance of the Earth–cloud system,    $ \times10^{-7 }\,F$
(b) the charge stored in the “capacitor,”    C(Round to the nearest integer)
(c) the energy stored in the “capacitor.”    $ \times10^{8 }\,J$

  In a photocell, ultraviolet (UV) lightd6+xm ueg(cu )t6s9z/1ihyfa provides enough energy to some electrons in barium metal to eject them from a surface at high speed. See Fig. 17–33. To measure the maximum energy of the electcxzs+yg)6h1 it a9fumu(d6/erons, another plate above the barium surface is kept at a negative enough potential that the emitted electrons are slowed down and stopped, and return to the barium surface. If the plate voltage is $-3.02V$ (compared to the barium) when the fastest electrons are stopped, what was the speed of these electrons when they were emitted?    $ \times10^{6 }\,m/s$

  A point charge is placed 36 cm from an ide.embu +xi2ki(f1 0abr ntical $+33\mu C$ charge. A $-1.5\mu C$ charge is moved from point a to point b in Fig. 17–34. What is the change in potential energy? $\approx$    J (round to one decimal place)

  A capacitor is made from two 1.1-cm-diameli2xoc)j gi/6ne3 mb +ter coins separated by a 0.15-mm-thick piece b)li m 23+cixoeng/6jof paper $(K=3.7)$ A 12-V battery is connected to the capacitor. How much charge is on each coin?    $ \times10^{-10 }\,C$

  A $+4.5\mu C$ charge is 23 cm to the right of a $-8.2\mu C$ charge. At the midpoint between the two charges,
(a) what are the potential    $ \times10^{ 5}\,V$
(b) the electric field?    $ \times10^{6 }\,V/m$  ----待选择----leftright 

  A parallel-plate capacitor with plate area29 foiv b6wf.e $2.0cm^2$ and air-gap separation 0.50 mm is connected to a 12-V battery, and fully charged. The battery is then disconnected.
(a) What is the charge on the capacitor?    $ \times10^{ -11}\,C$
(b) The plates are now pulled to a separation of 0.75 mm. What is the charge on the capacitor now?    $ \times10^{ -11}\,C$
(c) What is the potential difference across the plates now?    V
(d) How much work was required to pull the plates to their new separation?    $ \times10^{-10 }\,J$

  A $2.5-\mu F$ capacitor is fully charged by a 6.0-V battery. The battery is then disconnected. The capacitor is not ideal and the charge slowly leaks out from the plates. The next day, the capacitor has lost half its stored energy. Calculate the amount of charge lost.    $ \times10^{-6 }\,C$

  Two point charges are fixed 4.0 cm apart from each other. Their charges arxxd,u.wuu i :gxg1h nk5y,t ,r /ptcvsr::9+ ze $Q_1$=$Q_2$=$5.0\mu C$, and their masses are $m_1=1.5mg$ and $m_2=2.5mg$
(a) If $Q_1$ is released from rest, what will be its speed after a very long time?    m/s
(b) If both charges are released from rest at the same time, what will be the speed of $Q_1$ after a very long time?    m/s

  Two charges are placed as shown in Fig*n zy7t0 )wnlhb6mos.s+ 3sfv. 17–35 with $q_1$=$1.5\mu C$ and $q_2$=$-3.3\mu C$ Find the potential difference between points A and B.    $ \times10^{ 5}\,V$