If two points are at the same potential, does this mean that no work is done b a4+l6 :;ykb6rwjsq x2p159wqjbd gc in moving a test charge from one point to the other? Does this imply that no force need be exertedx5qp bd9b46c2aj gkjlw ;1sw y:+r 6bq? Explain.

If a negative charge is initially at rest in an electric fieldhy e*6fh h0ps3, 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 ceh6yp3 hh *sf0hange in each instance?

State clearly the difference (a) between electric potential and esh w /nf +p+nw+ijqzds ts0/(p0pz t,,lectric field, (b) between electric potential and electric potential en +/ns ( sqtpn+i,hzzw,fpd+0tps w0j/ergy.

An electron is accelerated8ae o;u z28hhk by a potential difference of, say, 0.10 V. How much greater would its final speed be kuze;a2h88 ohif it is accelerated with four times as much voltage? Explain.

Is there a point along the line joining two equal positive8h l12+a5uos;c f4yvq.pi iy:qkcwg6 charges where the electric field is zero? Where the electric potential is zero oiucyw42y8+ckah6vs i: ;flq1 pqg5.? Explain.

Can a particle ever move from a region fuum3s5nsa y3/e .9nbof low electric potential to one of high potential and yet have its e/fs39e bu5u.ysam3n nlectric potential energy decrease? Explain.

Compare the kinetic energy galovul0gjusk;l5s3+ dfk*d0 + ined 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 li.o: ih h4rxca5nes cross? Explain.

Draw in a few equipotentiau fd;,ij s/hwnlk+ lt4-t7pgm5m/ l*sl lines in Fig. 16 – 31b.

What can you say about the electric field in a region of space that has thi+p jq) w/riw5e same potential throughout?)wq i5ijw+/ rp

A satellite orbits the Earth along a gravitational t)xfy;;zfv3p equipotential line. What shape must the or vpf;y )t;3fzxbit be?

When dealing with practical devices, we often take the ground (i jj 4o)7/ufiz,73 biyxrjbe,the Earth) to be 0 V. If, instead, we said the ground was how would this affect (a) th7x4rz eu,jo )ijbiy,/bij3f7e potential V, and (b) the electric field E, at other points?

When a battery is connected to g:3/x bf(7t-yw pbkl ha capacitor, why do the two plates acquire charges of the same magnitude? Will this 7xy:pt g(/bw-b klhf3 be true if the two conductors are different sizes or shapes?

We have seen that the capacitance C depends on the size, shape, ana9tavb q54w( gc9:n5* hlgk odd position of the two conductors, as well ag(c k q5on 9:dhtg9*4w l5abavs 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 fixqcvh ,stfb - veye,.b86 shp);2q dv*eld 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 e2heb(n7ywk8 p z9t* aulectric field do in moving a proton from a point with a pote8ny(t 7h 9e2pwu*ka bzntial 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 awj*ijq)r6nm h +ri20tccelerates through a potential differencen rrtiq*i2hwj0m6+j ) of 23,000 V in a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquiresnh2/ u ,y9tuxl f(qpc8 $7.45 \times10^{ -16}\,J$ 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 thed. 6 * luuqc mmt5/l;akv+ku9p potential d;*mpt/6ud+lumu. c9kv a5lqkifference between them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field ofpz ba:7s(p+p c $640V/m$ 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 lk2p/ e7gggf/to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field between two parallel plates connechab3 zyrai*k5; c9y0*gpdy v-ted to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is needed to give a helium nucleus .q9 :rxbo+cqnfz hs 02$(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 200-V power supply, are separated b dna w/yz*m0v3y an air gap. How small can the gap be if*mayz /0w 3vnd the air is not to become conducting by exceeding its breakdown value of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an external force to move ap z1i hcd-g-so45gy*n $-8.50\mu C$ 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 kineta /gzd lna1)x/b i;uhv7/,f wpic energy
(a) 750-eV,    $ \times10^{7 }\;m/s$
(b) 3.2-keV?    $ \times10^{7 }\;m/s$

  What is the speed of a proton wrmali* w1y8(.km p8 afhose kinetic energy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (which is a heliumyah-56 rbyu 1m 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 15xllo;,gw e20e .0 cm from a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creatr80 e8y cjcf:xes 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 conductpz y t/2ueko,7or carries a net negativep7e ku/yo,t2z charge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potential a distance o vs09cus2u.wwf $ 2.5\times10^{-15 }\,m$ away from a proton?    $ \times10^{ 5}\,V$
(b) What is the electric potential energy of a system that consists of two protons $2.5 \times10^{-15 }\,m$ apart — as might occur inside a typical nucleus?    $ \times10^{ -14}\,J$

Three point charges are arranged at the corners ofqqz/ y x.*p bwwkyor1.j4+ e-q a square of side L as shown in Fig. 17–25. pyq/.*q+ x1y oe -wkb4wzqj r.What is the potential at the fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts frh0pb.2/gyn rwf- xa.e om rest 32.5 cm from a fixed point charge with $Q\,=\,-0.125\mu C$. How fast will the electron be moving when it is very far away?    $ \times10^{7 }\,m/s$

  Two identical $+9.5\mu C$ point charges are initially 3.5 cm from each other. If they are released at the same instant from rest, how fast will each be moving when they are very far away from each other? Assume they have identical masses of 1.0 mg.    m/s

  Two point charges, $3.0\mu C$ and $-2.0\mu C$ are placed 5.0 cm apart on the x axis. At what points along the x axis is
(a) the electric field zero    cm leftof $q_2$
(b) the potential zero? Let $V\,=\,0$ at $r\,=\,\propto$.

  How much work must be done to bring 8c w49 sl drf)vzlm,oi (tu:i.three electrons from a great distance apart oi4 . ifruwlsvd( 8 ct9lz:m),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 cm noro* 0+kszy+me mth 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 t;m;ec4a*c abptqg 5,d o 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,jiq/;2 d /puhtab.hv( as shown in Fig. 17–27. Determine ;q udh tip2(bv/h.a/ja 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 proton pk s 953qtrx/d*p0 oeg(the nucleus) in a gtqr0 3*pe5pxosk9/d 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 protonaxwklevweza4(d3 hv qz38/u-s x:i6 9 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 potentiadzor1 r/hr sbh2nsxq ij5g0 4v36 3l6al due to a dipole 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 vector, poivpb gn76 ;l60zsv2vrf nts from the negative to the positive charge. The water molecule, Fig. 17–287zv 02g f lpvbsrv;n66, has a dipole moment which can be considered as the vector sum of the two dipole moments, $\vec{P}_1$ and $\vec{P}_2$as shown. The distance between each H and the O is about $ 0.96\times10^{ -10}\,m$. The lines joining the center of the O atom with each H atom make an angle of $104^{\circ}\,$, as shown, and the net dipole moment has been measured to be $p\,=\,6.1 \times10^{-30 }\,C\cdot m$ Determine the charge q on each H atom.    $ \times10^{ -20}\,C$

  The two plates of a 4 4u,m svhi co-pwa2:h7fb9zncapacitor 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 capacitor hold)/fo+ y 2o*fv+3gsvojbj2c bk $+2500\mu C$ 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 hold6 f7ldgupubyd ir2 /7cyl*;3z jwu9(p7sx(wks plus and minus charges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference between two short sections of parallel wirew iu l/qdg:dw3o l,kq:z.7h*n in air is 120 V. They carry equ 3 g/w u wqk:qlohd.*,di7ln:zal and opposite charge of magnitude 95 pC. What is the capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows from each terminal of a 12.0-V battery when it isuiad-i 4-nkaweeyax f ;. 5ay,1(tbs0 connectebyt wa4y.d 0f5s axeu( 1e-kii-a,;nad to a $7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired. What area must the pm j -p+kvn;ge-lates have if they are to be separated by a g ;vn-ke -mj+p2.2-mm air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitog;o ul6bh27 prr increases 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 yk j9va(wdh78 $8.5 \times10^{ 5}\,V/m$ 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 oppositwsgv+ .:*lg qne $5.2\mu C$ 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 pla 5+x4o xcz9.pjcfx qu.tes 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 batt*1(locq2r buya+7;fm, codrsery (Fig. 17–29a) and then is disconnected from the battery. Wdclb;s(rm qcuro fa ,y*172+ohen 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 plat 3(l/f8vq tl9x upt;lres 5.5 cm on a side that are separate;uxrqlvp9( l 38t/lftd by 1.8 mm of paraffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circ kf55dodyvm.vm*j x 9:ular plates with a radius of 5.0 cm separated by 3.2k. fmd y5v9m5vj:*xdo mm of mica?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected to a 22-V battery. If n1l-j ba19-nj9 ixh caw,;kkt a piece of mica is placed between the plah-nnb ljc9w ,9k-tj x a1k;ia1tes, how much charge will flow from the battery?    $ \times10^{ -7}\,C$

  The electric field betwe-c*-ejbx7 kcac.us-s en the plates of a paper-separated $(K=3.75)$ capacitor is $ 8.24\times10^{4 }\,V/m$. The plates are 1.95 mm apart, and the charge on each plate is $0.775\mu C$. Determine the capacitance of this capacitor and the area of each plate.
   $ \times10^{--9 }\,F$
   $m^2$

  650 V is applied to a 2200-pF capacitor. Ho ds 0)l1ycl4sfw much energy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shock a heart that is beating erratit03qxy9lko i7p 5mbk9 cally. A capacitor in this device is charged to 5.0 kV and stores 1200 J of energy. What is its capacitance? 9 ky5kxql9 tmib30op7   $ \times10^{-5 }\,F$

  How much energy is stored by the electric field between two square plates, 8. 0e2gvqki+xl x s,wg5/0 cm on ak5e/ ,gxqlv g2wi0s+ x side, separated by a 1.5-mm air gap? The charges on the plates are equal and opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is b 57b148twl0rl4,qbcy wsag rs38xphgz4 s8iassembled by placing two 9-in. pie pans 5 cm apart and connecting them to th wy8457 srhbtc8g3x18zr gs,ib0wpbl4 a4sq le 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 capactr,no;svms9j 1g6nj1pe z,gx wk4j:* itor 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 (sp0 2 oohz0 psww dam9t*t.x6f-h m;5ma) the potential difference is doubled, and (b) the charge on each plate is 9az-wsm0 h2somod5 pt06wh;.x * ftmpdoubled, 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 acceleaq dpq2 6x(9lk/dr bjx;/n ,nsrated horizontally by 7.0 kV. They then pass through a uniform electric field E for a distance of 2.8 cm, which;lsq n/arqd/(xpj, 9kd6xbn 2 deflects them upward so they reach the screen top 22 cm away, 11 cm above the center. Estimate the value of E.    $ \times10^{5 }\,V/m$

  Electrons are accelerated by 6.0 kV in a CRT. The screenv6pud k6+ qmn iqxd)oo)v*vpd, 7**sv 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 vary to sweep the beam fully across +nvuddqo7o6v) * s )q vpk,x*6m* dvipthe screen?    $ \times10^{5 }\,V/m$ to    $ \times10^{5 }\,V/m$

  An electron starting from rest acquires 6.3 keV +- puqii2r,ygof KE in moving from point A to point B. gy r2 -qui,pi+
(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 4.2 MJ of enex7ycw+6. ry0u fgc2ubrgy 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 xt: wjq,z2se ta11o3sx:1 exsfield 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 picture tube, electrons are accelera)lrqyw0 qq+d3jhvx 8,e k/ su(ted by thousands of volts through a vacuum. If a television set were laid on its back, would electrons be able to move upward against the force of gravity? What potential difference, acting over a distance of 3.0 cm, would be needed to balance the downward force of graqdx8,/j 0qvrs +wk )e(3qulh yvity so that an electron would remain stationary? Assume that the electric field is uniform.    $ \times10^{ -12}\,V$

  A huge 4.0-F capacitor habo9y*9g a, bvyjtum*o5mk,v6s 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 it is fuldkq9nbv - fp abp1l8)s7 5xsmwq7 os8.ly charged, after which it is disconnected from the battery. A slab of paraffin is then inserted between the plates. What will now be the vowbsqmna7o)l bf5s q 7dv88p x1.9-pksltage between the plates?    V

  Dry air will break down (*a /(bxd+8s x sbqhqyif the electric field exceeds $3.0 \times10^{6 }\,V/m$. What amount of charge can be placed on a parallel-plate capacitor if the area of each plate is $56cm^2$?    $ \times10^{-7 }\,C$

Three charges are at the 91t;-rg*he1 ps,lvtec hkiy,corners of an equilateral triangle (side L) as shown in Fig. 17–30. Determine the9rt,-h,y;eihv ps *teck11 lg 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 Pyre qbzqb2ls*z+,,u cfn1 x glass is placed between the plates, how much charlzf1bzq*+ 2cs,bu ,nq ge will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally from 5:69wdz rkz1 olt xws3 f42davrest 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 potential difference of 250 V (Fig. 17–31). At:xz5o6f14 3ztas9v d rk dlww2 what angle $\theta$ will the electron be traveling after it passes between the plates?    $^{\circ}\,$

A capacitor of capacitance ; euv i3ag0:ju$C_1$ 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 8bl 7hux0 sy337s apdrwant to make a 1-F air-filled parallel-plate capacitor for a circuit you are building. To make it a reasonable si7byas3pdxh87r us 0 3lze, 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 electri-krydds 2)l.6r4v*g shb 5kqc c 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 pulst) *lwaru-e79p wbmndc + lkb7//ti1d ed 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 differue/zmk m +0li4ence between the Earth and the bottom of the thunderclo+im 4e0k/ ulzmuds can be as high as 35,000,000 V. The bottoms of the thunderclouds are typically 1500 m above the Earth, and can have an area of $110km^2$ Modeling the Earth–cloud system as a huge capacitor, calculate
(a) the capacitance of the Earth–cloud system,    $ \times10^{-7 }\,F$
(b) the charge stored in the “capacitor,”    C(Round to the nearest integer)
(c) the energy stored in the “capacitor.”    $ \times10^{8 }\,J$

  In a photocell, ultraviolet (UV) light provides r+rz o8gqig1w* w5(b henough 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, anotz8 hbro(*w5 i+r gq1wgher plate above the barium surface is kept at a negative enough potential that the emitted electrons are slowed down and stopped, and return to the barium surface. If the plate voltage is $-3.02V$ (compared to the barium) when the fastest electrons are stopped, what was the speed of these electrons when they were emitted?    $ \times10^{6 }\,m/s$

  A point charge is placed 36 cm fro.wp x2, rxuyc(ew5 ;vfm 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 fromuzzbr;wy :n:4 two 1.1-cm-diameter coins separated by a 0.15-mm-thick piece of paz zw::rny 4ub;per $(K=3.7)$ 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 arew1i .wry,oq*o:dyfdd;ek2 n(ry0 c n 2a $2.0cm^2$ 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 othft)ti37wsb5 lqm(vg9f-imbh rrrres;.+( e;er. 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 , rk.anba50*iu w +gbgFig. 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$