If two points are at the same potential, does thg z8 e n*akyahw0tyzmant;,7d5 vf2)0is mean that no work is done in moving a test charge from oneadazm;yef8 vz75 , a2tnh0)gyw *tkn0 point to the other? Does this imply that no force need be exerted? Explain.

If a negative charge is initially at rest in an electric field, will it movo(70nx pcqy49lyp d2we toward a region of higher potential or lower potential? What about a positive charge? How does t ldx(9w27 pnqocyp4y0he potential energy of the charge change in each instance?

State clearly the difference (a) between electric potential and electrt7 (- z twk/7l.h:pgydv;numb ic field, (b) between p( wuldt7 gt:v.y-kz/mh n7;belectric potential and electric potential energy.

An electron is accele h8mnygl( t)qz 8ijp+r:i51rk rated by a potential difference of, say, 0.10 V. How much greater would its final speed be if it is accelerated with four times as much vonqi5+g 8h: zryj8t1l)mr i pk(ltage? Explain.

Is there a point along the line joining two equal positive charges where t -ozmp8:djnw :he electric field is zero? Where the electriw8:-omn:p dzjc potential is zero? Explain.

Can a particle ever m ilpa3gx:jc77 ove from a region of low electric potential to one of high potential and yet have i:xi gcj7 pa3l7ts electric potential energy decrease? Explain.

Compare the kinetic energy gained by a protojfr,7ncby4,c;kdng7.ixm ;dn $(q=+e)$ 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? Explaini6 kqpkm:c )ga+s/;cz .

Draw in a few equipotential lines pj 43nojul1*;cfrn vdiw, z47in Fig. 16 – 31b.

What can you say aboub*ykf z8or+xqdx,9v 8 t the electric field in a region of space that has the same potentiaby8q xo vr,zx9dfk+*8l throughout?

A satellite orbits the Earth along a gravitational equipgoz cyl ;+f1 s2a31lwaotential line. What shape mlo yl3 ;gc+asa12w 1zfust the orbit be?

When dealing with practica5h6lrbee2 6jbl devices, we often 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 other le5bbh6ej 2r6points?

When a battery is connected to a capacitor, why do thel7r8pwfh; ch* 4 jwg3a two plates acquire charges of the same magnitude? Will this be true if the c;jh3pw7w4lafg r*h8 two conductors are different sizes or shapes?

We have seen that the capacitance C depends on the size, s:a.joce v /dh t;(wou)hape, and position of the two conductors, as well as on the dielectric constant K. What then did we mean when we s:u/vh (ceot) jo.d aw;aid that C is a constant in Eq. 17 – 7?

  How much work does the electriz0t(dh,57wi huf54 z( mau kwgc 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 do in moving a proton fromcl y3 9x7am abu x.t,jam:(:zv a point with a poten:xu .3aal,:m9a ( tjcvyzbx 7mtial 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:r; iqfv,m /sn gain (in joules and eV) if it accelerates through a potential difference of 23,000 V in a TV picture tu, mf:v;i nsrq/be?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires w bfr m:9)vjm51 pna(x$7.45 \times10^{ -16}\,J$ 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 elf j,*j)gg;nn azp0k0me m:ig)ectric field between two parallel plates 5.8 mm apart if the potential difference between eg0;gzfp0,g*jj n):m ) kinamthem is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field of :gfx qcm l2)l6$640V/m$ is desired between two parallel plates 11.0 mm apart. How large a voltage should be applied?    V

  The electric field betx sb tlzzg716s/q2r5 iween 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 connected to a v r;j40ggghn7 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential differen (nu3.kwug (xsce is 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 power supply, are k*r)m80h*6g3qik n wymkmbe 0.4s jwpseparated by an air gap. How small can the gap be if the air is not to become conducting by exceeding its breakdownwnr4m8 .im3kps0* m *kw6qjh )0e kygb value of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an externpms .ya l(72fe c,/pbfp, fumka,d03pal 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 1y(w2c ck nm.uokk 1*/eyazg) an electron with kinetic energy
(a) 750-eV,    $ \times10^{7 }\;m/s$
(b) 3.2-keV?    $ \times10^{7 }\;m/s$

  What is the speed of a ovi4e1*c b485u il7q;vh 6ds 2ifzlc jproton whose kinetic energy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (which iagz kneq1b r us905i80s a helium 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 potential 15vuu:j-:3rqksmdb5 .h.0 cm from a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q createh - wq*kjax:,es 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 carries a net +jbu.t )q6 51toor cpunegative c1poqb 5tc)r.ou6jt +uharge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electq*rpuil d h d7)8ab;x 4guxd*:ric 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 at2s nolkvz n8a6m2pvdqy87 5r4 the corners of a square of side L as shown in Fig. 17–25. What is the potentiavn 8l2aps 42nod8m5v rzy 76qkl 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 chjzy,y jw1ergnz ,y:.: arge 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 electr ;kjwj 5)qvljtx-zcf19 y(.us ons from a great distance apart to y wkj)( v.jj xf1clsu-9z5;tq$1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is 72 cm north :z8 zdb vv.k 4ei:h:esof 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 accelerate a proton (radiu/xg rgtmec g x/8c yg)(a7axt l6x714us $1.2 \times10^{-15 }\,m$) 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 ch5tdwkx fwgz2g*y a 14jq3 t016. bneiiarges are separated by a distance d, as shown in Fig. 17–27. Ddn*gq1j0y35 g ew.i k6tz21wtafbix4etermine 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 orbi4pxnw h(lf8/i ts a proton (the nucleus) in a circular or l84xp/i(fn hwbit 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 proton1/e9wipaw/ j1zukht 6 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 whal m++ab wx nm)/hefspc +lhwuz8k)ym- -y-(-ose 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, points from the negative to the posi lqky/964ug-/yui4e l dodj.etive charge. The water molecule, Fig. 17–28, has a dipole moment which can be considered as the vector sudqe/u4 .9ik6-/ y l4 jguldyeom 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 hofx+:xz 0v -pjvld $+2500\mu C$ 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 capa3dl8loo;r 7xtb mm wa1p1n wyvb5)2y1l .t-lmcitor 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 uiqu 3r8ymu hr2*p+1d plus and minus charges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference bep(pa 8tgqf1 1*d(svsatween two short sections of parallel wire in air is 120 V. They carry equal and opposite charge of magn1(t sfdpaa gvp*( q18situde 95 pC. What is the capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows fror0q73a azob-(a5h p- hhc9lakm each terminal of a 12.0-V battery when it is connected to araz5oa -ahc7 l(9qhh3 kb0-pa $7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired.d06 cbkx(a4lv What area must the plates have if they are to be separated bb6l0x(4vcak d y a 2.2-mm air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitor increasesah e(y +ly bkf90*gi0u 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 3,kq8;ezqh nibb 2 j4j$8.5 \times10^{ 5}\,V/m$ 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 opposfw/(4 y 1 hi gcp(0zjey:vi-t-q*tdjyite $5.2\mu C$ 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 electr51gy5 pa/jfofic 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. 17–2mg v*fl )guso:(w( 4mm9a) and then is disconnected from the battery. When this cm *g(mv( lwo4gf m:)suapacitor $(C_1)$ 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 pla xy7zc4-yzm8 0vbahw3 tes 5.5 cm on a side that are separated by 1.8 mbz m0 az c47hy8xv3yw-m of paraffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circular plates wx0:skttdb/ w7hc 45b8jpa4t cith a radius of 5.0 cm separated by 3.2 mm of micabjac5: 0/4wdttsbkhc tx87 4 p?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capa kxxnp.--h/ vjcitor is connected to a 22-V battery. If a piece of mica is placed between the plates, how much charge .x- v/xhnpk-jwill flow from the battery?    $ \times10^{ -7}\,C$

  The electric field between the plates ob.+r k(sh q2pdf 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 stored?3m-;lrwp)5frihcw n -    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shock a heart that is beating erratic lpy ;(tvu 2:jmq,j2rfally. A capacitor in this device is charged to 5.0 kV and stores ymlu(tjf2,jq2vp: r ;1200 J of energy. What is its capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the electricflpo.vp ;ks-l 1 vqbr:0qc- i, field between two square plates, 8.0 cm on a side, separated by a 1.5-mm air ga:ko;s,--plrq qb1 v cpv0if.lp? The charges on the plates are equal and opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is assembled by ppe;i- bxn-(x*z ptyt 8lacing two 9-in. pie pans 5 cm apart and connecting them to tp- itb;*xxt8-ze n (yphe 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 cap tm8+)dvb;iojq t -+o hmgli78acitor 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 ckl6 w civdd.:m 8+ssn;hange if (a) the potential difference is doubled, and (b) the charge on each plate is ddk cl;v8 + nim:wds.s6oubled, 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 kV6iw6jzzb*+ga 9: n l hmnm/;yw. 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 awaygjihza n6 9mw;z+*:m6/bylnw , 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 screew z 2dl3xcc/vo 7p;mwby+w 57rn is 30 cm wide and is 34 cm from the 2.6-cm-long deflection plates. Over what range must the horioz+w7v3;x cy5p7wcbd/ mlwr 2zontally deflecting electric field vary to sweep the beam fully across the screen?    $ \times10^{5 }\,V/m$ to    $ \times10^{5 }\,V/m$

  An electron starting fr)73o zd)hpmvfo * iv0vom rest acquires 6.3 keV of KE in moving from point A to pointv0of)voi37mhzvd) p * 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 transferszq se7icv*;nv85: a;m xoyo. j 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 umizs ;v1 v +*,pgy+hnthe Earth’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 accelerated by:wmf; o8a* o( (jaxp sxc5n0ub thousands of volts through a vacuum. If a television set w: 5b(s(m8wn aopc*a;ouf 0jxxere 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 heai t(lddi 4.es7t 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 *8fl2uo: hlgnt4og k8connected to a 24.0-V battery until it is fully charged, after which it is disconnected from the battery. A slab of paraffin is then inserted between the plates. What will now be the volg 8go28nt l hl:uk*4fotage between the plates?    V

  Dry air will break down if the elecv-8tr-pmq 0c8 v/zybltric 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 tridfuv7g* i5bv;gf1vo +g:4b :icgjci 6 angle (side L) as shown in Fig. 17–30. Determine thebg:dg1o ivu* vj4i;gfi+ g 6vfc:b 75c 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 connected to a 9.0-V battery. If a piece of Pk u6+k(q r1e2i)oatw2(lo z tryrex glass is placed between 6w)2r(r k lz+ (ooaiqetk 2ut1the plates, how much charge will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally from rest in a television picture tube -ws o: :y kraj1 . qj:kyvxif+f-ad9i.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 pote jfijf rx1s.y: id-ya9k:oq-v:wk+ a.ntial 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 capaci u27r ,l0+ju)l fajas,cd6tkltance $C_1$ 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, suppose you want to make a 1-F air-filled 2)e*jjf+hi v 7gy1x;4ojbr.v iib mv1 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 viry7i1goj+ fx) 4hmb2v1j*vj. e;i bachievable?    $ \times10^{-16 }\,m$  ----待选择----YesNo 

  Near the surface of the Earth there is an elec q3w v55f.h1*poyf 35 dkbytiqtric 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 nitro3n,mh7pnyy) 4dvwhh 5 gen 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 betweeh7(uw1yc p: brn the Earth and the bottom of the thunderclouds can be as high as 35,000,000 V.r7pbch:yu(1w 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 pccwa4 1 1lta ot/jlg+o, (mshuqf4 *og+:b7ttrovides 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 electrons, another plate a tm/1ut:tosfl1+cw 4+ g4,(b c t* 7glaaohoqjbove 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 idenpqrc: 01nui0k 2d zc6atical $+33\mu C$ 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 b7oj+l,t6rahw y a 0.15-mm-thick piece of paperor,wth6j7l +a $(K=3.7)$ 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 area ygy.l mc4xx ) l3;dd;evv;9 co$2.0cm^2$ 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. T9fq, ky4ei6akt z )m,lheir 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 placed as z 0k(cshwfb ++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$