If two points are at the same poteds32 er ns9ucr*ag r8wb8,hv1ntial, does this mean that no work is done in moving a test charge from one poinhd8u ws21cn9a 8 3,err*svrbgt to the other? Does this imply that no force need be exerted? Explain.

If a negative charge is iniym2hi g)r16j ztially at rest in an electric field, will it move toward a regionj 2y )hmgzi6r1 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 potential and electric field,k i4l)um,.0g*3z qpfkv ou.qc (b) between electric potential and electric potential enkg cq4u ) .kmpf0 uoli*3.vz,qergy.

An electron is accelerated by1h pn)0kz35u3jmrc ez a potential difference of, say, 0.10 V. How much greater would its final speed be if it is accelerate)5p ure30 nj3 zmc1hzkd with four times as much voltage? Explain.

Is there a point along the line joining two equal positivc*5i+ss o-/2g4+mqkd vd etz we charges where the electric field is zero? Where the electric pot+ z2ce 5tv/ 4q skswig-dod+*mential is zero? Explain.

Can a particle ever mopct*kbrxk,6yq 35x9 yve from a region of low electric potential to one of high potential and yet have its electric p6 9k xtrck3y5bqy px*,otential energy decrease? Explain.

Compare the kinetic energy gained by a p(xb)ddtnag/2wz*u fb- : wf,vroton $(q=+e)$ 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?g4b. jklf4 p vx3 :mg*yuz;d4l Explain.

Draw in a few equipotential lineomfxdt .pp7 .)s in Fig. 16 – 31b.

What can you say about the electric field in a regioa hl4o6d* *kjr9zm,ibn of space that has the same potenrak*6zi b94 ,*djhoml tial throughout?

A satellite orbits the Earti)/buzx,6mad1 :i2d;ndmc qih along a gravitational equipotential line. What shape must the orbit c)x,m /idq1n6;b zdi m2auid: be?

When dealing with practical devices, we often take the ground (thw:8 :a wpx5im3vl5uuie Earth) to be 0 V. If, instead, we said th 5v83ipi uu:aw5l :xwme 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 twoby 3wliz -;/3+mgs,9.hyfrbm20r vk -oefy iu plates acquire charges of the same magnitude? Will this be true if the two conductorsbu 2/3rg3mw zs . f eolhy b0-,-r+;iimfk9yyv are different sizes or shapes?

We have seen that the capacitance C depends on the size, shape, and position n nhad-xqus, :g/ar cv. hx1+2of the two conductors, as well as on the dielectric constant K. What then did we mean when /ch d+x2vn , x-gn:.urqsha1awe said that C is a constant in Eq. 17 – 7?

  How much work does the electric fielwo )twhva4k 85*6 04b kslxfkgd 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 f, szf)l wg (dt9a17dyf9or+uv ield do in moving a proton from a point with a vfr 9wuoga 9 1t)y 7z(dls+,dfpotential 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 acceleradm9:4lyelde5dgxvn6*t /+; o)i gzhc tes through a potential difference of 23,000 V in *5vz6+ld;exe o:nh tlg)4ygd i 9cmd/a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires 4u7,0 ps4hcih ezt qd:$7.45 \times10^{ -16}\,J$ 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 elec) wxdfxw(07 untric field between two parallel plates 5.8 mm apart if the potential differ)7wx0wdn ufx(ence between them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field ofl;hf kpxyfnw0f)2 rt b .-*u0i $640V/m$ is desired between two parallel plates 11.0 mm apart. How large a voltage should be applied?    V

  The electric field between two parallel plates connected to a 45-V batteryen/+ k9ash 6oc is $1500V/m$ How far apart are the plates?    m

  The electric field between two paral bi. /l8b;m6uu5ifig8 sa;ivpjd m g)rr5.rh6lel plates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is ned6- vhux7 / fse8/aw hx(f-poleded to give a helium nucleus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, cono 8 al1lpeig ,a icq6(2/dsp r,ux67sbnected to a 200-V power supply, are separated by an air gap. How small can the gap be if the air is not to become conducting by excgb 21x87ld,p iiacral( e/uoqps, 66seeding its breakdown value of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an external force to munqh:2 :fddiya5f/t p*/tym -ove 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 electron with kinetic enerae2/ify: 3)8u msr+nubfacf 05w f4jpgy
(a) 750-eV,    $ \times10^{7 }\;m/s$
(b) 3.2-keV?    $ \times10^{7 }\;m/s$

  What is the speed of a paie :s *hi7+bovf+/-yo3 ck bjroton whose kinetic energy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (wzt+ej 6qqwge wf q 8ea1-6tz6.hich is 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 15.0 cm /r n4lan o5+pjfrom a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates an electric potential ogry p0o6 d3 zsf51.vmcf $+125V$ 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 ou mm,v3dpcxv cff :y,n+ 6x++wf a football. This conductor carries a net negaticxf mv d,+:cvmu+,6npy wf 3x+ve charge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potenq9yboj t3.k: ztial 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 l./t+lmrooq)e. bst;at the corners of a square of side L as shown in Fig. 17–25. What is the potential at the fourth cornero;r/.l+ q). bostelmt (point A), taking $V\,=\,0$ at a great distance?

  An electron starts from rest 32.5 cmvl);j 7k9v,y;p a mql13;7y w nsiirwk 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 three0 b85b)ctck:sl. kldn electrons from a great distance apart .0c blck)k:t5nsd 8lb to $1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is 72 s0vt-bf1js(7o4bg t f 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 urbxj*k0 i- 4kyfpkp1s)tr;m 2sed 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 a distance d, as shh 1f0a(tj-pi jown in Fig. 17–27. Determine a formult - (pi1j0jfhaa 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 orbpn bia262g6 vag:* lrz8hxou-its a proton (the nucleus)bo x n2g6-pha6z 8g*li:u avr2 in a circular orbit 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 proto;qvly ;km(6xjpfmsd2b* cg1, n 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 di.fam3 ,c51px zrd ;vqopole 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 vectwsx1t:-j kf78y0 k wulejvhg7w) ,dd4 or, points from the negative to the positive charge. The water molecule, Fig. 17–28, has a dipole moment w1u:k-ke07vltdx)8 jfj ywd wswhg7 4,hich 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 s: xrtpr1xl ;9capacitor 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$

  The two plates of a capacitorutif3 wb je7,e(u 1vw+ 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 ni2b h0*+lyp:xe2g 5i*yuvuf plus and minus charges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference between two short s00mcal kq u2o4ections of parallel wire in air is 120 V. They carry equal and oppkl qc04o20mua osite charge of magnitude 95 pC. What is the capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows from each terminau9h yzd :xfp//l of a 12.0-V battery when it is connected t/ df p9zuxyh/:o a $7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired. What area must pauah7 l.*m3po*z x+nof9iv 2the plates have if they are to be separated by afzu*+9. vanp 3lao72om* hixp 2.2-mm air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitor incr*6ybh6 qeck+o 0xv4 qsa7ykg 1eases 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 jy/ k yd+-no 9mavc*1ibjls bg*w.v); $8.5 \times10^{ 5}\,V/m$ 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 opposituvj-qv/i s7dorb8* /we $5.2\mu C$ 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 f c)xhw;i e ihm:2.fl+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 12va,2x) :wbshvjm 2u v25-V battery (Fig. 17–29a) and then is disconnectea2x 2,: vvwbj s2mhuv)d from 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 plates 5.5 c+0 4+yq ns0jx4 tyfuzem on a side that are separated by 1.8 mm of parsy+ 404y zjufn xt+eq0affin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circular plates with a radius of i49 - yxr6c t+sh(qdhx5.0 cm separated by 3.xsi-hdt6 9 q(rc x4yh+2 mm of mica?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected to a 22-V battery. bg if i58n+z*nIf a piece of mica is placed between the plates, i igb+n5zfn8*how much charge will flow from the battery?    $ \times10^{ -7}\,C$

  The electric field between the plates of a paper-separatvs3 jo7g /. u/nny9jeqed $(K=3.75)$ 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 2200s h3swr6wvz. 8-pF capacitor. How much energy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shocki*g. /) -ffngzvtvzn, a heart that is beating erratically. A capacitor in this device is charged gzn).vgizffn /vt , -*to 5.0 kV and stores 1200 J of energy. What is its capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored g1pqx eeur+70by the electric field between two square plates, 8.0 cm on a side, separated by a 1.5-mm air gap0r x1uqp7g+ee ? The charges on the plates are equal and opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is assembcx5;q;e;bwdq se:k f:led by placing two 9-in. pie pans 5 cm apart and connecting them to the opposite terminals of a 9c5;bqq e:wd :s;ekf ;x-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 capacit byhkwwgpc b75 5ifn522fru77or 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 potential differ *ciouc+r+;+sotod5-aj /ln:b u7q ha ence is doubled, and (-cuh5ro :sj lqnac+tooa/d +*7b+iu;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.pnz -e;em e/cq.17fqw0 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 cm above the center. Estime.z1f7/pn -;wqeqc e mate the value of E.    $ \times10^{5 }\,V/m$

  Electrons are accelerated by 6.0 kV in a CRT. The screen is 30 cm wide and is 3 4z;gy d n3+cabamiq*:4 cm from the 2.6-cm-long deflection plates. Over what range must the horizontally deflecting electr n;yi z*:d+gcma3ab q4ic 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 ke u*0l zo 3owpvaa0*o*l iewk0(V of KE in moving from point A to point Bzo0wk0 p3 io lw*0*vo (aeau*l.
(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 3u5v.*yn n8:vofpx ol 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 Earth’s surface whose magnitude is abouthyio(4 g;vx ffh3,g u( $150\,V/m$ How much energy is stored per cubic meter in this field?    $ \times10^{-7 }\,J/m^3$

  In a television picture tube, electrons are acceleratedud 3fuqg;b5f9tf6r*q5c 7 rbd+af.jm by thousands of volts through a vacuum. If a televf b;frtf+r*bdj c79m.gu3655da f quqision 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 energz umgc4l+,x.zy 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 ujikcg 9,x7 e2 jjq8(qintil it is fully charged, after which it is disconnectg( j9qikji2 jec7x8,q ed 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 field exceed *qu9ewox 9;+2fzku *psd l8nqcw6h r;s $3.0 \times10^{6 }\,V/m$. 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 cornef,j pn u5gb4fk+yu-k d69lt1e rs of an equilateral triangle (side L) as shown in Fig. 17–30. Determine thef-4 bky jk u9,pd6+efu15ntgl 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 Pyqj:cxz:,zbwva * qc-7c(e u2 urex glass is pl 7vc-zq 2:( bca*ucuwz qj,xe:aced between the plates, how much charge will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally from relgjn w2 8ck.t*st in a television picture tube 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 potentn8 2ctj*k.lwgial 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 capacitancegw t(3/ s.jpnl r)wgv8 $C_1$ 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 bi a-4hd.vq f oa2s.u7ipnl; +kkg 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, suppose you limit the plate area to What would the gap have to be between the plates? Is this practically achievable? uf.+2h-q v;.a4nil ado7p skk    $ \times10^{-16 }\,m$  ----待选择----YesNo 

  Near the surface of the Earth there to mkr*1y i4qvh:4f,t is 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 pulsc(x am7* +- ;zry:ip (lqqd ei+cq3loped 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 the Earth and the cyb- hywkm/of(a4+5 ej3* lea 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 5b caym- jekof a(ly+/3*4whe, 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)d*9g-2s6,0 lkfju,datc ye; wizp yr) light 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 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* ,wp2 ;u cyfed sdt z,jilk)-9a6gry0 $-3.02V$ (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 w g4y 7it-ymst j0ng16identical $+33\mu C$ 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 trp/dbyi d6(;o8aa4ixwo 1.1-cm-diameter coins separated by a 0.15-mm-thick piece of pap ra/; iy6bapx4dd8oi(er $(K=3.7)$ 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 areauqn1.h+* hrm3iq0a)a/lfu bv e hge 0bg(b:/r $2.0cm^2$ 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 othesx+/f ni *rdhrc,nu 5fc),fi (r. 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 placed as shown in Fig. 17–35 witk:6lgpm1q0ms:9ry4 37rcw2 u fb q dgjh $q_1$=$1.5\mu C$ and $q_2$=$-3.3\mu C$ Find the potential difference between points A and B.    $ \times10^{ 5}\,V$