If two points are at the same potential, .4 v ef.0s af9/snapqvdoes this mean that no work is done in moving a test charge from one point to the other? Does this imply that no force need be exerted? Explain0q..a f fs p/ns9veav4.

If a negative charge is initiabb b4xwyc +q qg(7k82elly at rest in an electric field, will it move toward a region of higher potential or lower potential? What about a positive charge? How does the potential energy of thec q7xy2k 8be q4wgb+b( charge change in each instance?

State clearly the difference (g rl4-fzvsg tt 6n8:-xa) between electric potential and electric field, (b) between electric potential and electric potentiatz:8xsgn- v 4 rtf-lg6l energy.

An electron is accelerated by a potential difference o doxdcwp:t, ;1f, say, 0.10 V. How much greater would its final speed be if it is accelera:,p c;d xwt1doted with four times as much voltage? Explain.

Is there a point along the line joining two equal positive charges zp-f7 ihqe*m7ob *q; uwhere the electric field is zero? Where the electric potential is zero? Explaibq7;uz homf* 7*peq-in.

Can a particle ever move from a region of low electric potential to one of hig,*e/ -m zfu+jcwbqln9h p zbwlum*c+q j/9-f, enotential and yet have its electric potential energy decrease? Explain.

Compare the kinetic energy gain3po* hvo fdiqd6ri;q4u(k,h- ed 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 lines cross? Explx14dht 7 b5o zkayk0nbfa:e 2;/udr3lain.

Draw in a few equipotential lines in Fig. 16 – 31qa0 rgmb07ei4d ))/*mvwvejw b.

What can you say about the electric field in a regcy3dzxwb0k, q-si(2 xion of space that has the same poq3w ( b-2kxsyd ,0xizctential throughout?

A satellite orbits the Earth along a gravitational equipotential lvg 1)j;h ds rp(rom3xei6-t )ft+ q0gkine. What shape must the orbit 1( 6fi) s+geq ;m)ttjgrk0orx3phd -vbe?

When dealing with practical devices, we o89o;y9ct28zpf n/fvnuqb8 fw ften take the ground (the Earth) to be 0 V. If, instead, we said the ground was how would this affo;88wt29 cbzynuq/f9vn fp8 fect (a) the potential V, and (b) the electric field E, at other points?

When a battery is connected 9lf:t p4p:xuk5pm dx+to a capacitor, why do the two plates acquire charges of the same ma94kx:tpp5px ld fmu +:gnitude? Will this be true if the two conductors are different sizes or shapes?

We have seen that the capacitancev pzuxj5;8pz3 C depends on the size, shape, and position of the two conductors, as well as on the dielectric constant K. What then 5;8u3zvj z ppxdid we mean when we said that C is a constant in Eq. 17 – 7?

  How much work does the electri /fhw4wg tbi-.+syz 9wc field do in moving a $-7.7\mu C$ charge from ground to a point whose potential is $+55V$ higher?    $ \times10^{-4 }\,J$

  How much work does the electric field dg 5rgi nsujmzi .8d7fd6l .:s9o in moving a proton from a point with a potentia.l :5jg9ui s6 sdd87znfm.i rgl 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 enexex n;/ s-+ii,87jf oi rzbx(grgy will an electron gain (in joules and eV) if it accelerates through a potential difference of 23,000 V in a TV pict x;z i/,7f in+j8(-xrsebgxioure tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires (stad5u.:ayf $7.45 \times10^{ -16}\,J$ 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 p dcrlle-,. mm9lates 5.8 mm apart if the potential el-. d,9mcrml difference between them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field of i-v+p vn9exs6$640V/m$ is desired between two parallel plates 11.0 mm apart. How large a voltage should be applied?    V

  The electric field betwj-2,jqnuq r 0b-; mjmqeen two parallel plates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field betwee g0rlp. w3iv*on two parallel plates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is s+iie,h0 6 *zkas-cfe needed to give a helium nucleus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 200-V powergi;7nd q u,r0r5 z,qsi supply, are separated by an air gap. How sm;di5 ,igs,rq0u7 z nqrall 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 extfhu*.owmz0k8tr a45u ernal force 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 electronq6y*c a2uo(rvxo wfz)10 lo )e with kinetic energy
(a) 750-eV,    $ \times10^{7 }\;m/s$
(b) 3.2-keV?    $ \times10^{7 }\;m/s$

  What is the speed of z 3rr7k5e3jw8jnh1kpa proton whose kinetic energy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (which is a helium nucle)ejz+a1 rir/*+ -p p6uj rtf/o nh1eh6fvdj3p us, $Q=+2e$, $m\,=\,6.64\times10^{-27 }\,kg$) is emitted in a radioactive decay with $_{KE}$ = $5.53MeV$ What is its speed?    $ \times10^{7}\,m/s$

  What is the electric wn 74 h/y0mtwtc*xld1 potential 15.0 cm from a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates an electric i5p0l d7uupi 8potential 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 footbal1 ebr7i8 (nykil. This conductor carries a net negative charge,in1i(8eky r7b $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electr g )bdpj1) vpls(q,he-ic potential a distance 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 corners of a square of side L 5rvte)n a3q;v as shown in Fig. 17–25. Wh vtq 3r;)ae5nvat is the potential at the fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts from n2 v3(81excyk ei)jgx rest 32.5 cm from a fixed 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 great distance ac gx *sl 46/gc xs881p:uyzrwipart zw6* 4/iyl 1:8c8sspgxcrxu gto $1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is 7-j a 2ue+3mnfg 4 k4gu,r3hfzcl4g d8z2 cm north of 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 ,jss,vg15s ixh; :nkfbe 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+e rmf32u)qig(1 bsc 2c(i rwjz +7jke separated by a distance d, as shown in Fig. 1s1( eijj+fi23 r mw( ru)qzgk2+ be7cc7–27. Determine a formula for $V_{BA}\,=\,V_B-V_A$ for points B and A on the line between the charges.

  In the Bohr model of the hydr;o(bb2 b 8/wt33r2bsm;sdubr y4uzbm ogen atom, an electron orbits a proton (the nucleus) in a circular orbit 8d r3o bbst/bzw3 mbbs mu24r;2buy (;of radius $ 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 prlwq;g0tnfxgp4iu1 q 7.6 f4fmoton 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 to a dipole whose dipole momxjue+s-hy8 kn17jk;bx+lo ( lent 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, points from the negaio8*)j k*qe nq7sud 3etive to the positive char3ijq)7s*dkqeo8 *e un ge. The water molecule, Fig. 17–28, has a dipole moment which can be considered 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 n8 p)..u8k9djc xh ath ug/c*ghold $+2500\mu C$ 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 capacitmv 6xg9-cxx2 /ou.xnfr rf 4,ahw4jo:or 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 chz+ol)7p 2i eikex /m2farges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference between two shod8rj icldbfg ;(;ygafp35c pji;v: 67 rt sections of parallel wire in air is 120 V. They carry equal and opposite char g;i68lf;( ;dapjcpd73ivgj rcyb 5:fge of magnitude 95 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 *.:jyru7pvhz3ymv 3;sc;m q g when it is connected to a gyrs 3mzju.v3 myp*hq: c;v;7$7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor igpq ;qp rua/)x 5q5gz;s desired. What area must the plates have if they are to be separaqx /5qa;gpu5rq p)z;gted by a 2.2-mm air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitor increae l+kdyb82s r zzzr3ou+2 so9i8 ,l)wfses 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 1*hofhcndfulwg 5a wn 71 ,k1($8.5 \times10^{ 5}\,V/m$ 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 q ri-w72ltd, l wv*2w*9 mvyv kn:fu4i$5.2\mu C$ 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 electric fi pn gz*sfg(*-zeld 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(2)qt hsbckbs::h2ov a 125-V battery (Fig. 17–29a) and then is disconnected from the batterykbq:(2s2 )ohtc: bh vs. 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 plates 5.5 cm on u8w ffj)h*wr3di*s; ka side that are separated byrdh*f) k*wu8;ji3ws f 1.8 mm of paraffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circuv ex-:7c rg+bdogl h2;uod4v 1lar plates with a radius of 5.0 cm separated bg-1h e ;o+co7d:rg4v2vulbx dy 3.2 mm of mica?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected to a 22-V batteryagwdu) 47 mz5y. If a piece of mica is placed between the plates, how much charge )m 75zuywdag4 will flow from the battery?    $ \times10^{ -7}\,C$

  The electric field betwe1nmxno-.a v k)en the plates of 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 2anzih4+yr ay9ef n g78 sm+/ecapacitor. How much energy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shock a he3f* r3 h*pw+jy-plwlnart that is beating erratically. A capacitor in this device is charged to 5.0 kV and storerwwhj 3y-**p+ lfl np3s 1200 J of energy. What is its capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the electric field between two square plates, 8otc(lq4r 3u(oj t3 n3b.0 cm on a side, separated by a 1.5-mm air gap? The charges on the 43jrq(t nobl c3tu3(oplates are equal and opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is assembled by placinkbyk 3z7g mb*f)y,8 cdg two 9-in. pie pans 5 cm apart and connecting them to the op dfk)y ym7gz, c*kb38bposite 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 cappnt ,du +:r 11vd(rnsaacitor 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 ihdr+rq d4v 7i0w4e 8gc2o xfs48u;mqd f (a) the potential difference is doubled, and (b) the charge on each plate is doubled, as the capacitor remains connect0d gw78o4iseh +;mqdr8 xvu4qf4r2dced 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 z;:btq j3ihohsq x*v5.ut/t7 horizontally by 7.0 kV. They then pass through a uniform electric field E for a distance of 2.8 i:v*h5tq.z7bj ;u h3t/ toqxscm, which deflects them upward so they reach the screen top 22 cm away, 11 cm above the center. Estimate the value of E.    $ \times10^{5 }\,V/m$

  Electrons are accelerated by 6.0 kV in a CRT. The screen is 30 cgh y8isroxbz9 eq**)bq d;:sw8q gw/5m wide and is 34 cm from the 2.6-cm-long deflection plates. Over what range must the horizontally deflectinqsg9 e/zb8srq85wy )qg o x**h;:db iwg electric field vary to sweep the beam fully across the screen?    $ \times10^{5 }\,V/m$ to    $ \times10^{5 }\,V/m$

  An electron starting from rest acquires 6.3 keV of KE in moving from3 2,3. vbabpsz.xrf mi point A to pointp3,3r2zb xv.ibfam .s 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 e 4:2eszsoj,sj -d f.37bkjzwcharge 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 abou5 cg8(;t wovw dd*h/fwt $150\,V/m$ How much energy is stored per cubic meter in this field?    $ \times10^{-7 }\,J/m^3$

  In a television picture tube, electrons are accei )nnvew91i( elerated by thousands of volts th9ni 1 ei)nwve(rough 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 difference, 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 energy to heat 2.5ohy3+a0 rt+-+-ynq f ml, j ggfzl+3yj 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 battery until it is fully cha+ g2*xu+wnggi rged, after which it is disconnected from the battery. A slab of paraffin is then inserted between the plates. What will now be the volta+ig*w+ x ngug2ge between the plates?    V

  Dry air will break down k b5ezshj9f9sipy7:5fuca, 0q oi. 3aif the electric 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 the corners of an equilateral triangle (side L) as shoz*fkcc-8jsp6 mn 4i0axl0. 5tptjz d(wn in Fig. 17–30. De jdntz4 -ip *mtzc0lc(68xkpf05 js .atermine the potential at the midpoint 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 /a1,caaqze*fecn9s 6connected to a 9.0-V battery. If a piece of Pyrex glass is placed between the plates, how ae6ecqaa / z1 f,cn9s*much charge will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally from rest in a television picture tub/d/ 66sj y(f 0zh:whify0colu e by a potential difference of 5500 V. It then passes between two horizontal plates 6.5 cm long and 1.3 cm apart that have a potential difference of 250 V fu 0i6h/:0j/(cw6f zl yydho s(Fig. 17–31). At what angle $\theta$ will the electron be traveling after it passes between the plates?    $^{\circ}\,$

A capacitor of capacitance ume 6;ws6ob,f $C_1$ 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 big a farad is, su6o t /5a4o/kv hx2wpwgppose you want to make a 1-F air-filled parallel-plate capacitor for a circuit you are building. To make it a reasonable size, suppose you limit the plate area to What would the gap have to be between the platet 5vkxa ho/64p2 wwgo/s? Is this practically achievable?    $ \times10^{-16 }\,m$  ----待选择----YesNo 

  Near the surface of the Earth there sz a+ t:57 ejap3 1tkho6s3l26cthmgcis 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 pulsed nitrogem*/ ,*x(( h67v9qqjlaxjpu wdnew ze. n 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 potent.rul 1ym8u-m wial difference between the Earth and the bottom of the thunderclouds can be as high as 35,01wm8m-rul uy.00,000 V. The bottoms of the thunderclouds are 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) light provides enough energy to some elxc6* 1aej;;gzlk 7 qrqectrons in barium metal to eject them from a surface at high speed. See Fig. 17–33. To measure the maximum energy of the electrons, anotherxq z1rl6a*cqke7;jg ; 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 ideni:,tlfptnwt(npzwg/j8 8 4w*tical $+33\mu C$ 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-diameter coins separated by a 0.15z07ocr ;8dsebs sz7;c -mm-thick piece of papezss7; o z8r07scde ;bcr $(K=3.7)$ 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 witht p/fz nz m)701s1msk qac9kh6 plate area $2.0cm^2$ 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 fix5kd6yby;0u hur2w2pl 1cnn 5 xed 4.0 cm apart from each other. Their charges are $Q_1$=$Q_2$=$5.0\mu C$, 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 placedt8 .b593 mbg.xpyncvmm 4cf l4 as shown in Fig. 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$