If two points are at the same potential, does this mean that no work tzxu6do4a2t wr7e0dz6a1 u 7gis done in moving a test charge from one point to the other? Does this ima67odaex61 z2dz wu7t0ugt r4 ply that no force need be exerted? Explain.

If a negative charge is initiallyoc.:4qvm,j qw 6o ld;/xgzymi 3+q)fv at rest in an electric field, will it move toward a region of higher potential or lower potential? ovjmc g :ywf6)d4qoi,v;qxq/ mz+.l3What 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 g e a 2)niz14n4a4l2rsst*zl welectric field, (b) between ele4lzl n4ta4)rsi*wa1n 2z2sg ectric potential and electric potential energy.

An electron is accelerated by a po.xml.s93 nplu7:lur jtential difference of, say, 0.10 V. How much greater would its final speed be if it is accelerated with four times as mu l .u.lnsru mj7px:l93ch voltage? Explain.

Is there a point along the line joining two equal po auovkoxr p:0ddt-555 ujels 2a40+dpsitive charges where the electric field is zerotrouudke5: x- d lp4asod2j+vp 500 5a? Where the electric potential is zero? Explain.

Can a particle ever move from a region of low electric potential tu 22gtq1(noui o one of high potential and yet have its electric p t(qu2iuo1n g2otential energy decrease? Explain.

Compare the kinetic energy gad4: t-d/h sgilined by a proton $(q=+e)$ to the energy gained by an alpha particle $(q=+2e)$ accelerated by the same voltage $V$.

If $V\,=\,0$ at a point in space, must $\vec{E}\,=0$ there? If $\vec{E}\,=0$ at some point, must $V\,=\,0$ at that point? Explain. Give examples for each.

Can two equipotential lines cross? g8c q-bzb k-mxn -)y+yExplain.

Draw in a few equipotential lines in Figa7mdtw8d:rin 6+ r cl(2oy-o v. 16 – 31b.

What can you say about the electric field in a regif.dh rlkvj 728on of space that has the same potenhdk728 fjrv. ltial throughout?

A satellite orbits the Earth a9n(9ab9eaccnv i(0o n long a gravitational equipotential line. What shape na0v9e9n(in a9coc b( must the orbit be?

When dealing with practical devices, we often take the ground (the Earth) irh anf(;/* uqca 0y cq6h4cw)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 otfar6q (ihuy cc c0h*/qn w;a)4her points?

When a battery is connected to a capacitor, why do the two 6trrbmxiz(,j q(s2 m :plates acquire charges of the same magnitude? Will this ,m(jtrb6(q xi 2 srz:mbe true if the two conductors are different sizes or shapes?

We have seen that the capacitance C depends on the sizt.cy crp8:*ef e, 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*y8fre ptc c:. is a constant in Eq. 17 – 7?

  How much work does the electric field dowbfn+ bms7;8 e 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 movingg,a6xq7 00jtxa3set v a proton from a point with a potential ot 3067xexgtj sv q,aa0f $+125V$ 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 accelep ,d qvql1+v6gg.0igh rates through a potential difference of 23,000 V in a TV pictureqvv 0l,qidg+pg.6gh 1 tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires ra: kun3ekmn k3 d h-bt8 oz2h7j.0;en$7.45 \times10^{ -16}\,J$ 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 b cxkdc/ez68u m3oho2/ etween two parallel plates 5.8 mm apart if the potential difference between them /k82ou6zo hxemcc3/d is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field of;gcxui, (h1he $640V/m$ is desired between two parallel plates 11.0 mm apart. How large a voltage should be applied?    V

  The electric field between two parallel platescf 8 hj8+l34c jw8:jiuqpm -8ve n;shs 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 45-V battery is rzymbhw ex9.9vsa k d1( ps s)7p1g25i$1500V/m$ How far apart are the plates?    m

  What potential difference is needed to give a helium nucleusbnt5: /2xo ae8* yhyus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 200-V power supply, are sepav.i.d 3mrre0crated by an air gap. How small can the g3v redmr.i.0cap be if 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 agb57 6hhjf( 5da- yqdd $-8.50\mu C$ 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 u(civ3h wh )h;2jbpw.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 proton whose kinetic e(p75j+t ojgiinergy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (which is a helium mxfs /5k3tm-xetcn 23nucleus, $Q=+2e$, $m\,=\,6.64\times10^{-27 }\,kg$) 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 from dj 9, 7;fnx.lrmufd3qjt-7xea $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates an electric potential ofs-cy rf,tr+87 zwgy(dhuf*p:t.y k 8 a $+125V$ 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 amgn 1 8lzr/z0fo3yyi6 football. This conductor carries a net negative chaz3zrmo/ 1608nigf y ylrge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potentixkmd; h 1oy.:aal 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 at the corners of a square of side L as shown ixndt86 2p4 3f69vf gxrdvr2sen Fig. 17–25. What is the potenf2 3 xdpnrx26fets94grv vd68tial 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 cha /gc2-pv gwr324qt fijl*m6 aarge 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 dc+d 74xmcnf., -bqoqcistance apart c,bq7+c-4. cxfnd omqto $1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is 72 cm north of ad8a d n(h2+zqb $-3.8\mu C$ 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 tojb lo4g)ux f8/1z(pc x+xhox4 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 separatz7 -csfke( wye q(f0e9ed by a distance d, as shown in Fig. 17–27. D eqksey7c- 9z0((fefwetermine 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 hydrox gg p9/0+ckwfgen atom, an electron orbits a proton (the nucleus) in a c g0c/gkpxw9f +ircular 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 prs: 7tqrtcmt)cq25/ j coton are $ 0.53\times10^{ -10}\,m$. apart. What is their dipole moment if they are at rest?    $ \times10^{-30 }\,C\cdot\,m$

  Calculate the electr97 -rinvuo(7 i4 i4t *yfkspriic potential 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, points from the negative (j+q.b.tvqd b to the positive chartj.b(d+.qvq b ge. The water molecule, Fig. 17–28, 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 capacitor hond,oxv08y/p( hhweu)4ow njyu /5a( uld $+2500\mu C$ 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 cap95jgg6 jkh -io8 v(;sqngf1die :uqv dde067vacitor 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 plus and minus charges o4-w6zo3aif y yf $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference between)k g ta dk57vi/ v80-kctjbj6n two short sections of parallel wire in air is 120 V. They carry equal and opposite charge of magnitudec/kkb58d0vkt6nt 7ijj) a- vg 95 pC. What is the capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows from each terminal of ae-zmbc4w/y g . 12.0-V battery when it is connected toweb/4 c-my zg. 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 tonow49nod uc*, be separated by a 2.2o 4ud9* wnoc,n-mm air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitor increasesj0wcw fmdh w21 )69jle 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 of0hor )9 4l w(m/wwwygf $8.5 \times10^{ 5}\,V/m$ 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 oppos )o qffz+/v(:*-vw m pcu5hatdite $5.2\mu C$ 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 ofob9zv d:(ni:92hqj 2 bqt3mrb 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. 17–29a) anzbuau may ghz-c5nrw* va,;zpj/(6(5 d then is disconnected from the battery. Whenmua5-5z(r g z pnwbv,*(jyau;a/hc6 z 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 cunnzq3klfju0)a;hq. 5b0k t *m on a side that are separated by 1.8 mm of paraffin)nq .3*juhlb5ktn f0zu ak0;q?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circular plates with a radius oflu( /uiv- zxe6 5.0 cm sep(i /el-x6 zuvuarated by 3.2 mm of mica?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected to a 22-V battery. If a piece os p6a5)7 tnxcef mica is placed between the plates, how much charge eacn7txps 6 )5will flow from the battery?    $ \times10^{ -7}\,C$

  The electric field between thegfz;25hw n/ ks 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. How much ene y00k 2f1j5;wh z7srzeof d-plrgy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillatolkotj16 u k4+lr is used to shock a heart that is beating erratically. A capacitor in this device is charge jolku1 6tlk+4d 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 ima;jg ,th6vsw5 g3h1between two square plates, 8.0 cm on a side, separated by a 1.5-mm air gap? The charges on the plates are equal a,m5 ag;iw6th 1vh gj3snd opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is assembled by placing two 9-in. pie pans 5 cm ofv:nm)sa 76y4i8siw apart and connecting them to the opposite terminals of a 9-V battensfwiy87) ovi:46 as mry. 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 hal+g4wizcrl *0fn 6s b7s 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 mazj))o , ku-cstored in a capacitor change if (a) the potential difference is doubled, and (b) the charge on each plate is douj)uocz m,-)ak 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 accelerash +;i0je) xk7 nc3anmted horizontally by 7.0 kV. They then pass through a uniform electric field E for a distance of 2.8 cm7m03n+ akej ;c)xnihs, which 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 accele5w2ge) qhl/h-d:ibt9dm g k1wrated by 6.0 kV in a CRT. 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 figehiwk9qg/m:d2)ht5d-l bw 1eld 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 keb w/:+ w6unmyhV of KE in moving from point A to point B. 6y:hb+m wwun /
(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.jkxukbnp 806/2 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 l0eq ,+ hjksn3e /9srmwhose 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, epyc9 ; .z9ede- )mtbb-ky h/tklectrons are accelerated 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 gravity so that an electron would remain stationary? Assume that the electric field is unifod t-y y9p. ;tb)eh/9k-bkm zecrm.    $ \times10^{ -12}\,V$

  A huge 4.0-F capacitor has enough stored energy tza )tu xz 91ri7)q.qxty kb68ao 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 batte k3lpz36z3tqgk-qn p0ry 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 now6z t np3g3zpklk30qq- be the voltage between the plates?    V

  Dry air will break down if thepap67. yqlreujqa 768 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 corners of at-m 5wvpfd4 s*n equilateral triangle (side L) as shown in Fig. 17–3svf5 t mwd-*p40. Determine the 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 isy1dvjo2j4ewy : xovz n7) o01b connected to a 9.0-V battery. If a piece of Pyrex glass is placed between the plates, how much charge will then flow fr bx1 v2wj1z on:yyoj) 47v0oedom the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally )*9p)l 5 enrbnghxnf1 from rest 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 a91nf b)nn)h5*xlep r g 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 capacitancetxyzr 5s7 vzf jchh8+l8m2ee )n0b0e / $C_1$ 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. gzff5./qcqpfpu; u128ook a a farad is, suppose you want to make a 1-F air-filled parallel-plate capacit ffp;f1. 2/u5g8c.akqquozpo or 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?    $ \times10^{-16 }\,m$  ----待选择----YesNo 

  Near the surface of the Earth there is an electric field o7z l 2koatyqg-m8ddlhtaw9 2.r8(m8 b f 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 nitr,.a0 w/hb 0bexr1ebg 8rdh;vbogen 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 diffe hzwu9;(yo*jc rence between the Earth and the bottom of the thunderclouds can be as high as 35,000,w uco;y j(z*h9000 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 k f-0 ouzl. z4gwk1)sxenough energy to some electrons in barium metal to eject them from a surf.10zf4wsxug kz-) lko ace 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 $-3.02V$ (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 identical 2+oxt*c(qi)8n2mux wb *ilfi $+33\mu C$ 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 f or e2suzgea0)3(jn brzs32r*rom two 1.1-cm-diameter coins separated by a 0.15-mm-thick pier*33zb0u 2zj ne )gose(asrr2ce 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 rs*ozc1l v n;c8 -kk5yarea $2.0cm^2$ 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. Theirdpg+ 2ubw)d g.5q fxu6 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. 17–5w)beo )(nawvqm ef3535 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$