If two points are at the same potential, does thi11gy* vc ojzsf98yc1mz v4xq9s mean that no work is done in moving a test charge from one point to the other? Does this implc *ycjy1soqfg9v9vm14 zzx 18y that no force need be exerted? Explain.

If a negative charge is initially at rest in an electric field, will it move to;/ vda6-lcf(7k m3(yqi uqqdq ward a region of higher potential or lower potential? What about a positive charge? How does the potential energy of the charge ydq6( a- f kmqc3 l;7(iu/dvqqchange in each instance?

State clearly the differyqlcm,z i/m.)8j :lfc ence (a) between electric potential and electric field, (b) between electr cmif)l:zly.8jc /m q,ic potential and electric potential energy.

An electron is accelerated by a potentiak9u etc- q8d (r+,u1xinp,tnyl difference of, say, 0.10 V. How much greater would its final speed be if itk,un (en8tr 1quxyti,c -d 9p+ is accelerated with four times as much voltage? Explain.

Is there a point along the line joining thon3f/izwcz84y3.4h 8 yv u fpwo equal positive charges where the electric field is zero? Wherezy 3 .8nwzfhcu/ 8pvh4yfo 43i the electric potential is zero? Explain.

Can a particle ever move from a region of low electric potential+znl- f u0*,q ku xeumjmwk6:aos8-4 x to one of high potential and yet hx4n-u+0ml,smej kuu*f6: x8o ak- zqw ave its electric potential energy decrease? Explain.

Compare the kinetic eesm2v 239/mcn 00qe,b kv ybzhw- 7qwonergy gained 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? Explaiibeeg71f 4 wyb z.j(o1n.

Draw in a few equipotential lines in Fig. 16 – 3,mlcqu1m e8n 2,4bbba st5/zn d)ot/l 1b.

What can you say about the electric field in a region of space t3c*kvd8ub,9 ewa(g tww* am3ihat has the same p* 3ug v,(8wm3kiaa cbwt9dew* otential throughout?

A satellite orbits the Earth along a gravitational equipot 97gl0knq ;rdiential line. What shape must the orbidki gnr;79 l0qt be?

When dealing with practical devices, we /t* n;4f juxuyoften take the ground (the Earth) to be 0 V. If, instead, we said the ground was how would this affect (a) the potential V, and (b) the electric field E, at xy t4j;n*/ufu other points?

When a battery is connected-xl5t( a-l okg to a capacitor, why do the two plates acquire charges of the same magnitude? Will this be true if the two conductors are dif(l- t5okxl-ga ferent sizes or shapes?

We have seen that the capacitance t/co8r.kkg9q /:e dm eC depends on the size, shape, and position of the two conducqo//m:kdr cek 89g .ettors, as well as on the dielectric constant K. What then did we mean when we said that C is a constant in Eq. 17 – 7?

  How much work does the electric field do in mo zfp:ym8+0a y8gb: fqiving 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 fie1icwuwln d8/y ve(g,+b*pr /f ld do in moving a proton from a point with a potential ogcupwyr,l e1i/8b+d/(n* v wff $+125V$ 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 1n0:tku ok9fq) tesqn)*r8 u7jsnm4m gain (in joules and eV) if it accelerates through a potenti794q jo q:)nn msntmtk e)01f8u*rkusal difference of 23,000 V in a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquiresa(v rao4ovl -p3j(f n) $7.45 \times10^{ -16}\,J$ 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 5.8 mm a.eblidb0 5il pfr e)c5e ttx)s:5 *cf+part if the pote5xblfei5te0 f*t b+rec li :5pd cs).)ntial difference between them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field of)ifqik8:ip h , $640V/m$ is desired between two parallel plates 11.0 mm apart. How large a voltage should be applied?    V

  The electric field be+pdja z7 nob5ng +i:7uhtxg6) tween two parallel plates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field between two parallel plates connec8pl 8ifsnf.+e ted to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is needed to give afdu5 u5o*wzb. helium nucleus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 207zmxu652km-ag sh43 oa )xgka0-V power supply, are separated by an air gap. How small can the gap be if the air is not to become conducting5z g gm)ka6 4uaamo 27k3xs-hx by exceeding its breakdown value of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an external force to movetkd0. x9 4qzw c1mdx9v 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 ell7o n:6pbd(jb - q(0 sf4ckbjfvhwrh 1/ -d3vfectron 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 energy is 3.2 keok;-f4)ejnyakbwi 97cdi0b ea o44*jV?    $ \times10^{5}\,m/s$

  An alpha particle (which is a helium nuclev4 l)swu k 6py6vt6gj7us, $Q=+2e$, $m\,=\,6.64\times10^{-27 }\,kg$) is emitted in a radioactive decay with $_{KE}$ = $5.53MeV$ What is its speed?    $ \times10^{7}\,m/s$

  What is the electric potential 15o6x vn0 sfzhd3t0 -y:d.0 cm from a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creatdy k)3eei.vfk5i 5u/les 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 conductor caj7e g 9o(b+) dnp 5glggpl5uo9rries a net negativ9o5lpngplgg u+e(j 7bd )9o g5e charge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potential a distance of x jj( +xk8,t1bt k*mqe$ 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 .ksl3 1y+r3vws npfh9 corners of a square of side L as shown in Fig. 17–25. What is the pok93 fw 3srhsl+1nv.y ptential at the fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts from rest 32.5 cm from a fixed point charge wiroc+.1:9lcb8g v6:u bisc ateth $Q\,=\,-0.125\mu C$. 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 .8 p,jo9,h-y fii4q-jstvr pdto bring three electrons from a great distance apart tfq-rjdsyi , .ht8 i4-o pv9p,jo $1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which ijyxgm 8i/j y)(o2 iu1ks 72 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 be used to sbpk4i b*,g7pin+a;lo1-qo y 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 a diste:7am w fphv:*ance d, as shown in Fig. 17w:7ehpvm* : fa–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 hydrogen atom, an electron orbits a pro5r: b,maf*oei)yiv6v ton (the nucleus) in a circular orbit of radius *,rif e)iya o5vbv:m6$ 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 proton c6h6f0omc zuj;y8/gh 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 wh 0p7 2ws13bhmgh(duq1/u6dp kyfl lk5ose 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, cozjnc0 ,+ c1swansidered as a vector, points from the negative to the positive charge. The water molecule, Fig. 17–28, has a dipole moment which can be 1+cjan,w0czs 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 u- bp )jmoy.0ihold $+2500\mu C$ 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 capacsz;+yvcggzln bz7l 1 0rj54 .aitor 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 holad:vdzt*5u- d -1ekzv ds plus and minus charges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference between two sho4u t;(x dsuz5nrt sections of parallel wire in air is 120 V. They carry equal and opposite charge of magnitude 95 pC. What id 4nuxzs (;5uts the capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows from each terminal of a 12.0-V battmr( wo / una*;hhkn.w3 np3t v)-t3zzkery when it is connected .om )tpa(krkh/w3huz*wv;3z 3 ntn-n to a $7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired. What area must the plates have if they are to dlodk)w s gk pxg.g4.*:bo-t8 be separated by a 8)dkt xlsbo :-4.g gwko*g.pd2.2-mm air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitor injr7bf(d w2*tp spw5z7creases 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 olj2 ed3pc 5z-$8.5 \times10^{ 5}\,V/m$ 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 opp tgjt2;c()3 aenc7gs qn)s wo,osite $5.2\mu C$ 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 field g 22.2qs jes/vdhyk.4a)vo. . np7xi fmcjrt9between 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 aho k94duiv7s+ a;ski: 125-V battery (Fig. 17–29a) and then is disconnected from the battery.s7k+ukovai;hs d:i94 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 zoyhi-u 3x7t6cm on a side that are separated by 1.8 mm of par3o yz iuh7-6txaffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circular plx 4lb -jh,yv7jates with a radius of 5.0 cm separated by 3.2 4ljx- v,7hjyb mm of mica?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected to a 22-V battery. If )u cbg+70 adkca piece of mica is placed)kc70c b g+uda between the plates, how much charge will flow from the battery?    $ \times10^{ -7}\,C$

  The electric field between the plolmxnsn3:g7d*vv2; uates 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 capacitor. How much t+j: ap ei6bk9n 9de+*q vysa-energy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shock a he s28:d ukfekdqy:14 nb)j f:woart that is beating erratically. A capacitor in this device is charged to 5.0 kV and stores 1200 J of ener neyo1d:d:k) bkjq:wf 42 8usfgy. What is its capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the electric field between twqd(r*5 n yen+ ucvc6q2o square plates, 8.0 cm on a side, separated by a 1.5-mm air gap? The nv (dcneyc qrq*+562ucharges on the plates are equal and opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is assembled by 2s qpn6+qd 9,2ae/qpii3b u uqplacing two 9-in. pie pans 5 cm apart and connecting them to the opposite terminals of a 9-V battery. Es b ,qs92i/2udpuq36 nqp +eiaqtimate
(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 capacitor aui6cpk 36vj)gj0)gchas 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 potential diffdaghy hgw,z3bo8(c+:erence is doubled, and (b) the charge on each plate is doubleh+,wy o( d:8hzg3 acgbd, 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 a+hnixj3g7y1(q emjp. re accelerated horizontally by 7.0 kV. 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 cimqg y1jxh(7n3j+pe .m 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 3 u 5zr3:vfqmb f (b: 4dzss3pe*(m(oj*pk0eht0 cm wide and is 34 cm from the 2.6-cm-long deflection plates. Over what range must the horizontally deflecting electric field vary e3b(50u(zbfd vtp(4rpz*3: :ms ehf kqs m*joto 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 from point A t gby+ 7*z -llgxw+r9yio poxlwz*7gi -yb++ ly9grint 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 trau9 cq79p59po )jw qbornsfers 4.0 C of charge 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 Earr(z 8flnio 2.nth’s surface whose magnitude is 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 accelerate 5(ngu6 tpf 9qfo oon)y ,:h+xwqcyz,.d by thousands of volts through a vacuum. If o+owyh,utnzgq,9 yx.n6pq(fo c5f :) 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 ha/( u/j+v lyuveh skh-/s enough stored energy 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 battery until i*uc e;+8q6h pwrtxo 3ct is fully charged, after which it is disconnectec68 e3ch*p;x ortwu+qd from 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 electric fie il;eje,k78 b:zx98m)wbddp r ld 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/pdv sy /7u5iz (side L) as shown in Fig. 17–30. Determine the potential at the midpoint of each of the sides/uiy 7dsp5vz/ .

  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 of .y+l gt:vwt9csv/f1oPyrex glassv:tst w1v+o y/clf9.g is placed between the plates, how much charge will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally from rest in a tel)c3:e4gxkg nlf e/g 1*oys/g vevision picture tube by a potential difference of 5500 V. It then passes between two horizontal plates 6.5 c/3gyg 4le)ogxf/*1k cesgn:v m long and 1.3 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 capacitc bhyqn pp )xidq d,,.:fl9z8;ance $C_1$ 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 farn mq+3**y /2 ighw wa*5avipltad 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, suppose you limit the plate area to What would the gap have to be between the plates? Is this practically achie5vnhw 3y/ig*2ti*lapqa* +mw vable?    $ \times10^{-16 }\,m$  ----待选择----YesNo 

  Near the surface of the Earth there is an eleox c 63xawr*y/ctric 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 nitrogen ewzy 6hz:w6(9o hpmj+*eh* nblaser 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 thewb p.f :++x lxpvl-ki0 Earth and the bottom of the thunderclouds can be as high as 35,000,000 V. The bottoms of the thunderclouds are typically 1500 m above the Earth, and can have f p- xp wil.k:0+xlv+ban 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 provv/p4 79y6hrueta9htk ides enough energy to some electrons in barium metal to eject them from a surface at high speed. Seer6ut7t/k9v y h4hape9 Fig. 17–33. To measure the maximum energy of the electrons, 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 place ucx eyo17d2+zd 36 cm from an identical $+33\mu C$ 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-x)u vicazko 5-ime-2+b yb7.k,3lnz: q;xalacm-diameter coins separated by a 0.15-mm-thick piece of paper-u7:5 vmo;ckxezb3al- i .+nkiyxaz ,) aqlb 2 $(K=3.7)$ 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 platqwo,tf, +:k(0cyerpxyso.1 ;ilp; vie 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 fixed 4.0 cm apart from eachb vo2gj cfww3pdi sv uf5 ,7lo+5/g-v7 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 place bn2*lv:r*n8a ysj v 4tj+fp( 9kd4aced 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$