If two points are at the same potential, doel/vsqb8xsq :ve(9q 1 es this mean that no work is done in moving a test charge from one point to the other? Does this imply svq/xq8eq(ble s:91v that no force need be exerted? Explain.

If a negative charge is ini fuem.b q3yho7g)p:d )tially 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 the charge chanebd g:3)h)pf oqym7.uge in each instance?

State clearly the difference qrzi/ z w)k;1m(a) between electric potential and electric field, (b) between electric potential and electric pot)im; /z kw1qrzential energy.

An electron is accelerated by a potential differencod -z3qu:pml5 e of, say, 0.10 V. How much greater would its final speed be if it is accelerated witmd: u-o35qpl zh four times as much voltage? Explain.

Is there a point along the line joining two equal hv n/* gzrb;n89, v lxbkdhj;1positive charges where the electric field is zero? Where the electric potent9n klrzxh;;vbhb8 g 1dj,v*n/ial is zero? Explain.

Can a particle ever move from a region of low eo *5uc/o0lua/0 zcgd)je+hf olectric potential to one of high potential and yet have its electric potential energy ddo5u0lco)0/g/ahjo f *ceu z+ ecrease? Explain.

Compare the kinetic energy gained by a plqgk s:0 0(8,od:f )jiq:or+qndp gw mroton $(q=+e)$ 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? Explmo *mp ju;yu 5v6j cy6a+wld(7ain.

Draw in a few equipotential lines in Fiyyom1+ t)p3 f1ombrv 1g. 16 – 31b.

What can you say about the electric field in a region of space that has dfp 4d2gqhd ri5( hr0-the same potenpifq dh40 hgd25rr (-dtial throughout?

A satellite orbits the Earth along a gravitational equipotential lin m+yk2tig( w25p9loh ne. What shape must 9n(5ikywl2+mt2 p hogthe orbit be?

When dealing with practical devices, we often take thelme )n4 lq)edey 9:ou: 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 eeu:qm:y49 n) )d olelfield E, at other points?

When a battery is connected to a capacitor, why do the two c1/c* ssmw9wu6lz 2ug7 s.dmy plates acquire charges of the same magnitude? Will this be true if the two conductors are different sizes o*m/ cw679 gsd2zlc umywss .u1r shapes?

We have seen that the capaciox,5k41nqu3 zjvdp )i tance C depends on the size, shape, and position of the two conductors, as well as on the dielectric constant K. What then did we mean when we said that C is a constan ,dxnp3q15 i kj4voz)ut in Eq. 17 – 7?

  How much work does the elect,*e ji4npf: yeric 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 y)51i v-ax5cf)as 9 y kqrtu,fo x1n/c5j-oalin moving a proton from a point with a /cs) f1aokyxo)-9cq1, v5it5yl f5 rjnu -axa potential 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 anmmkm s+ ;c n0te n:7.w-)mmmvo electron gain (in joules and eV) if it accelerates through a potential differec mm0os mwmtm:m)-7.+knevn ;nce of 23,000 V in a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires 9,j p(brw9 poq$7.45 \times10^{ -16}\,J$ 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 apart if the(w w6et/mppt/,encr vwsvg+1 ull79 . potential dievw wrv96sln/+ .,ltp 1pwe ctgm/u (7fference between them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field of )uxxy a-4axr8gadq 0)uil7u qw6s5 t6 $640V/m$ is desired between two parallel plates 11.0 mm apart. How large a voltage should be applied?    V

  The electric field between two paraqcf9jvli0 w43 9hhu( sllel 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 xh.e2w+ zby. pto a 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is needed cs 8ctp)u 3kkib w*tbp:2c44q to give a helium nucleus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 20unz g8 vqcd:4kg6)f 8 p/4sieq0-V power supply, are separated by an air gap. How small can the gap be if the air is not to become co ni/qp6g z4)u8s4egcdf:vkq8 nducting by exceeding its breakdown value of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an external force to move1kq 6 8*txdedj 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 enehy q3 b*n:7n.(4x6 if)0qynbdk wf(mny j5qwfrgy
(a) 750-eV,    $ \times10^{7 }\;m/s$
(b) 3.2-keV?    $ \times10^{7 }\;m/s$

  What is the speed of a proton wh50jinn9i.v:rf5vvj yf, z.c rkm)9f k ose kinetic energy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (which is+j-,lfk0 .c d+y55 htrq foemd 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.oyl/7 v-5 9yky, k*eextq,q sjqb5jc40 cm from a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates an electric potentialahyy7 :d(qe h18xr) lw 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 ne ;tvz0(tmw0 s 0y wbfn qhw3f9a;gts8/t negative chargeffq ns ;;8a9vgtb w(ht 0ztyw0/m3sw0, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potential a distancvwi h1 ywp()e,wkch6. e 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 ark-ud *yd3vcvg7q.p f -ranged at the corners of a square of side L as shown igdpyv -kv.3d ucf-* 7qn Fig. 17–25. What is the potential at the fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts from rest 32.5 cm from a fixed poi rl8dsk7(k6sqe 0e 7oe k3txe*nt 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 i h+2nix* )g v.7fjyog.uwv n5distance apart *h2 +fn)7ivu w y.o5g ixvjg.nto $1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a whi2 (s ta-6xunk1m 0w q-8op-rixfgyd 3sch is 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 useds.leeb8my gg37a:1s n1kto : d 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 chargesjxb5s o/ c:.r/h vi,ll are separated by a distance d, as shown in Fig. 17–27. Determinesl,vc5x /h obji r.l:/ 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 electrout0q jnu,r4*ln orbits a proton (the nucleus) in a circular orbit of radius nu0l4q rtu* ,j$ 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 i71v;m 3kp co.smhsuv,)tc. bare $ 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 momentc1py9f )aeyb c;g6 h.rf;1jjs 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 ve9;z ze9fy. g+ibf*3wh dia*fqctor, points from the negative to the positive charge. The water molecule, Fig. 17–28, has a dipole moment which can be considered as the vector sum of the twoe i3qba;f. y g* *fiz99w+dzfh 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 holdh d,or41: owzv $+2500\mu C$ 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 capacit0 vd; m6*tae 2lhmr,jtor 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 plusuojp;c8: qr d* and minus charges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference betw.q-a+xj un f5ieen two short sections of parallel wire in air is 120 V. They carry equal and opposite charge of magnitude 95 pC. What is the capacitance of qu-jfa+nx5 i .the two wires?    $ \times10^{13 }\,F$

  How much charge flows from each terminal of a 12.0-V battery when it is connecterqr11a2 xfdrm ;o*;j1th) sv .xfix2 ndv r)fad xx;*shq 2.oxmrnf;jt1 21 r1i 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 bkby*3s4z m6fw8t fmr r.i2ufwawh,75e separated by a 2.2-mm t w,ff 4mw2sfr5* 6akuz73yhw.br8miair gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitor increase4wo ;q)wj ee)qs 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 ofb5+4 em ef-khi $8.5 \times10^{ 5}\,V/m$ 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 op2t khh. ;y*gus rjp73zh-k hl(posite $5.2\mu C$ 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 between the plates of a wr +k-p f;:hrq$0.80-\mu F$ air-gap capacitor if they are 2.0 mm apart and each has a charge of $72\mu C$ ?    $ \times10^{4 }\,V/m$

  A capacitor is charged by a 125-V battery (Fig. 17–29a) and then is disconnecbnt;o; rr. a0d;2cf9- abu6zy0l rmn pted from the ua0mn;td l 206 frbnaco;r.rz9b -y;p 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 sq 66j0yiwm gac;uare parallel plates 5.5 cm on a side that are separa6 0i y6am;gjcwted by 1.8 mm of paraffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circular plat9 yojyj4 y6y5;acx( yhes with a radius of 5.0 cm separated by 3 ;j9y5joyyyac h(x 6y4.2 mm of mica?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor ihpe+y6 ov5o c)s connected to a 22-V battery. If a piece of mica is placed between the plates, how much charge will flow from the batte5+y ohvo6ec) pry?    $ \times10^{ -7}\,C$

  The electric field between the plo(fzf,0a 0cvzk, f8yatn-n. iates 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 220rb5pvmxz :(.l .k2;cndf) qek0-pF capacitor. How much energy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shock a heart that is beating erratry//;d tk*gtwically. A capacitor in t dygtkr* tw/;/his device is charged to 5.0 kV and stores 1200 J of energy. What is its capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the electric field between two squarejb wul+d/8mk/xr e9o a*)ir2l plates, 8.0 cm on a side, separated by a 1.5-i)robdr+/le xaj9* lm8/wuk2 mm air gap? The charges on the plates are equal and opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is assembled by placing two 9-in. pie pans 5 c4ry 5o a,jj6 pwdenl0mr 8s4b4m apart and connecting them to dojs,ybr44a4wm n 5 80pe6jr lthe 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 capacitor hmbwc/ednjq/5 . cis0)as 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 aaczi3fc* *b*m capacitor change if (a) the potential difference is doubled, and (b) the charge on each plate is dou* 3cb*ic mazf*bled, 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 horb49jltaz h43q izontally 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 cm above the center. Estimate the value oflhbz 4ajq3 9t4 E.    $ \times10^{5 }\,V/m$

  Electrons are accelerated by 6.0 kV in a CR9doiaxq t aqty5(4n;hoz3q7. T. The screen is 30 cm wide and is 34 cm from the 2.6-cm-long deflection plates. Over what range must the horizontally deflecting electric field vz y; 5q. h4t( 9d3qnaxqootia7ary to sweep the beam fully across the screen?    $ \times10^{5 }\,V/m$ to    $ \times10^{5 }\,V/m$

  An electron starting from rest acquilu j ls4m4mgk*u (*0afres 6.3 keV of KE in moving from point A to sl0lj4mfa(mk4**u u gpoint 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 charge and 4. ,n(btrhm nu/.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 fiel yfd,kfm u9s:g70b8y rd near the 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 pictured +sfn0oj1nj za1)tz1 tube, electrons are accelerated by thousands of volts through a vacuum. If a television set were laid on its back, f0) tna1dj1os+1 zznj 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 heixkn271hzgzm8a0m x 12b (fzoat 2.5 kg of water from 21$^{\circ}\,C$ to 95$^{\circ}\,C$. What is the potential difference across the plates?    V

  An uncharged capacitorl 3nad ,6kk(yr is connected to a 24.0-V battery until it is fully charged, after which it is disconnected from the battery. A a63d,r n k(lykslab 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 exceep+h --xr iy+gp2yb2)thc)2e:rfb h leds $3.0 \times10^{6 }\,V/m$. 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 cor z mjaiydb*-oz+k pw2-cs7-b 0ners of an equilateral triangle (side L) as shown in Fig. 17–30. Determine the potential at the midpo-70pibzd ybkms-a z w-2c+*ojint 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 b3 /hb;4sg7i,axp ikgtattery. If a piece of Pyrex glass is placed between the plates, how much charge 4,b3/pai kgih7 g tsx;will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally from rest in a television picture tul,p,*xevv h cyt9s 5ach5 im 9pk/r,i3be by a potential difference of 5500 V. It then passes between two horizontal p,k,mi*,9pv h 3 s59x rcvhlyc5p /aietlates 6.5 cm 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 capacitcj bkbes;)0r:, 5 iysnance $C_1$ 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 gvur* x r:yq;7 5n sox4:8cttpyou want to make a 1-F air-filled parallel-plate capacitor for a circuit you are building. To make it a rest:4; u 5 xor*nc8ptyg: xq7vrasonable size, suppose you limit the plate area to What would the gap have to be between the plates? Is this practically achievable?    $ \times10^{-16 }\,m$  ----待选择----YesNo 

  Near the surface of the Earth there is an electric field of about4 uu*k(8ibk)lh;o.pt yp, mmg $150\,V/m$ 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 nitroge rtmc:gv: )apc 2g)o:hn 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 povwalrb33uxwr tl8ga x7r62 8:tential difference between the Earth and the bottom of the thunderclouds can be as high as 35,000,000 V. The bottoms of the thunderclouds arew vgrbu2 a7 x88x33walrt:lr6 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 energu;/piph(dx w *y 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 du ;w(*p/hp xienough 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 a ggo,)/jnq4r1tm+ kww n 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-cm-diameter coins separated by a 0.15-mm-thick 4f8) +ijdx3:1vrcgl,h 4g,j qzgkw gv pig c+vlqjw4 8rhf k,gi1 ggv3,j:zx4d)ece of paper $(K=3.7)$ A 12-V battery is connected to the capacitor. How much charge is on each coin?    $ \times10^{-10 }\,C$

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

  A parallel-plate capacitor with plate area (r7+1tag mzf x$2.0cm^2$ 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 cmng*o064)ntf blxdq:h 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 placed as shown in Fig. wo 0hj +p0jx5z17–35 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$