If two points are at the s5oxm99 iapu 5bmz7 m+same potential, does this mean that no work is done in moving a test charge from one point to the other? Does this i s b95pmiu9m+om7z xa5mply that no force need be exerted? Explain.

If a negative charge is initial.+ujqm -qmy 4qly at rest in an electric field, will it move toward a region of higher potential or lower potential? What about a positive charge? How dy m4uj+ -.qqqmoes the potential energy of the charge change in each instance?

State clearly the dife+,ta4z 32.q 0ssg tygw, zyueference (a) between electric potential and electric field, (b) between electric potential and elet0ag+s ,2u3,zw4tgzes.q y eyctric potential energy.

An electron is accelerated by a potezb*k+steusx d kyn,v4/i/r */ntial difference of, say, 0.10 V. How much greater would its final speed be if it is accelerated with four times aztbu+/sk/x* v4,e ir/kn* dys s much voltage? Explain.

Is there a point along the line joining two equal positive charges w-ircm,rz xc5) here the electric field is zero?mr)-icxzrc ,5 Where the electric potential is zero? Explain.

Can a particle ever move from a region of low electric potential ev4ftj74e(x 4kg kin8to one of high potential and n4ijvkxt4eef (k84g7yet have its electric potential energy decrease? Explain.

Compare the kinetic energy gained by a ped8x3w6(s9 als owus: roton $(q=+e)$ 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? Exp5, k nkdtcxz;0 l 4cvy0qfmx:.lain.

Draw in a few equipoten/sg it xm m92nf(*ccc +.8jczgtial lines in Fig. 16 – 31b.

What can you say about the electric field in a region of space that has the sal qgv1 k.dg/mps(g +2ome potential througmok 1qvgdps/(.l2+gghout?

A satellite orbits the Earth along a gravitational equipotential line. What sh bgo )u8mrx 2 .mss/kd)8orxy5 igg*z0ape must the orbit be?rgogzods2r. 0/y 58i )s8kgmxu * m)bx

When dealing with practical devices, we often take the ground (the Earth) to bw k y(wu(n23)2pcjruy01uhzue 0 V. If, instead, wery02huw u)u wz 3(ujny1pc2(k said the 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 thw2 rib mgg5u1i.fr i;+cy0s8l e two plates acquire charges of the same magnitude? Will this be true if the l; fib. 8yri+m0c52rwu1gisg two conductors are different sizes or shapes?

We have seen that the capacitance C depends on the size, shape, and position opbcp(hnu8-g+a r)lp .4 d*e* 2)dgel oq smbc,f the two conductors, as w -oe+rmnq 2b(g* )bd4ll.cs8 e guah*dpcp,)pell as 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 fhzaue cau*615i5t k-f ield do in moving a $-7.7\mu C$ charge from ground to a point whose potential is $+55V$ higher?    $ \times10^{-4 }\,J$

  How much work does the electric field do in moving a proton from a pointfml58i q)pqa.n;(9f 6 zoqks 0falbe/ with a potef90mq 6(iq qpo .lf)az /f8;ea5kl sbnntial 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 accel* zcg j4; j0b0mydruz0erates through a potential difference of 23,000 V j d4yb0;zj* 0gru0 mzcin a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires i a rpp3,yqv *f69w;la(ejw b1$7.45 \times10^{ -16}\,J$ 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 fiea z+xrks+3kb/ :qmf*dld between two parallel plates 5.8 mm apart if the potential baz/k+k +x 3*:drfsq mdifference between them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field of c hh-m-j,glg5$640V/m$ is desired between two parallel plates 11.0 mm apart. How large a voltage should be applied?    V

  The electric field between two parallelgkh2 rye j2n6k618nhj plates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field betw sc aq9osh/1-qq,2wbpo1ih1uc 1 0ad jeen two parallel plates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is needed to give a helium nuclec4c6 leokp p4,us $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 200-V power supply, are separated by ana2nq -z .qse, zz8r4gz air gap. How small can the gap be if the air is not to becomrq-za gqz,zznes4.28e conducting by exceeding its breakdown value of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an extern *dxhau1fzm *e7q, ym+al force to move a $-8.50\mu C$ charge from point a to point b is $15.0 \times10^{ -4}\;J$. If the charge was started from rest and had $ 4.82\times10^{ -4}\;J$ of kinetic energy when it reached point b, what must be the potential difference between a and b?    V

  What is the speed of,i*3q;0 0i-gaqtthaayv 5l.*sm zqq a an electron with kinetic energy
(a) 750-eV,    $ \times10^{7 }\;m/s$
(b) 3.2-keV?    $ \times10^{7 }\;m/s$

  What is the speed of a proton whose kinetic energy is 3.2 ke e3x:1liqeay,b/(0s tqlh; w iV?    $ \times10^{5}\,m/s$

  An alpha particle (which is a qa cw9 xyvq8;9eix2,z 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 potent)y umbxrk7j z2*klo11ial 15.0 cm from a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates an electric potential oft++tv3pd, rf g $+125V$ 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 cx 70frqqc;qr qw:;)r monductor carries a net negative cr)7:fwqq0 rx c;; rmqqharge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potentiae6x+ wi,f4 moal 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 shoak1gw-h:sl* wei;x(t wn in Fig. 17–25. What is the potential at thei:gtk*wx; 1(els-w ah fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts from rest 32w* s7g)x d/zj:,ao3z -f1o r n;qjlkb1vr+qtd.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 three electrons from j: hho 27y24psgo7sok a great distance apart ts2g o7syoh4pj2:k7oh o $1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is 72 cm no)( y jcow9be8is1,n wqshcg8 /rth 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 to accelerate a proton (radiu ;kyz3hr16gi as $1.2 \times10^{-15 }\,m$) 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 showu i1(oebwz9 x)2fpv o8n in Fig. 17–27. Determine a formuv8i fez9( xw21pbo) oula 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 3 oevapk/ni 7 rp81.bc(the nucleus) in a circulc/7.kbpaip 8e1 o vnr3ar 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-of0usa4(l.ck m p7vd 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 potenl0 2rbn4.odhku*gtv 5 k*eg2btial 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 ascd7aw u; v(ekc dbmu /1;rb:x: a vector, points from the negative to the positive charge. The water molecule, Fig. 17–2:u ba medxb;/r;c:( dvkw1 u7c8, 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 csugp9 .fh93wo (9hwv qapacitor 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 he 1 03 )ke3 fu2-f(ftn4wc7ibh lpegqdold $+2500\mu C$ 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 ple-r5ort 1yj7l .jj/rqus 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 wire in air is eyqp2 zcw3:( un ivlv-3pfq (3120 V. They carry -qe3 yvw q3pni2pc(:lz3vf u(equal 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 is connect-hs0nv na1er329b, whrc *yjh e2,r jevhhwb *9h3ny-s0 cnr1 ad 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 arew-: bejnix4f/6/aykb 79x lpz to be separated by a 2.2-mjn9 -xa zbw/:k f /xyb64ilpe7m air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitorivrbffx5 z4)2 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 /1vpl yq1 d91ksm ra7p$8.5 \times10^{ 5}\,V/m$ 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 opejif((a u32blposite $5.2\mu C$ 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 z, y(y hfi3w0kfield between the plates of a $0.80-\mu F$ air-gap capacitor if they are 2.0 mm apart and each has a charge of $72\mu C$ ?    $ \times10^{4 }\,V/m$

  A capacitor is charged by a 125-V battery (Fig. 17–29a) and then iss*rpvxz w)c tp9zpa)4:j;u6 x disconnected from the battery. When this cpv9jw zs;x46 :r)ua tpxp*cz) apacitor $(C_1)$ 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 cm on a sideo/f)84f u4al yq dlkj, that are 4j4y f)8 koau,/lqd flseparated by 1.8 mm of paraffin?    $ \times10^{-11 }\,F$

  What is the capacitanceas9l t+7bp e(5pm-kaol5 s,ni of a pair of circular plates with a radius of 5.0 cm separa b-5l7(nos5ki+ p,tasa 9empl ted by 3.2 mm of mica?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected tv p;* b(sjui-p-wl*r qv; :nheo a 22-V battery. If a piece of mica is placed between qu;p nje-: vl-sh*(b*;p iwvrthe plates, how much charge will flow from the battery?    $ \times10^{ -7}\,C$

  The electric field blaox 2b mq,ikq p8c:7 4m.cy9eetween 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 (c+k)+v0meu sj; qs qk/v6atca 2200-pF capacitor. How much energy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shock a heart that is beating erratically53 wdwe :ftni,. A capacitor in this device is charged to 5.0 kV and stores 1200 J of energy. What is ,:ewfndi5 3wtits capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the electric field between two square plf f rl:bqoc:0 xe3wkv3y/1ww6ates, 8.0 cm on a side, separated by a 1.5-mm air gap? The charges on the plb::q/wclokwfwxvr0 y3 36 e1fates are equal and opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is assembled by placing two 9-in. pie panbvnc4 :zkm)- ws 5 cm apart and connecting them to the opposite terminals of a 9-V battery. E-4wb)cmv:nk zstimate
(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 cap3chpfp;hw :5hacitor 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 potentoqkl 4fv4b*5wc0 oiy 0 , ;hkv05akcddial difference is doubled, and (b) the charge on each plate is doubled, as the capc4yd*;kdh5 0oqoc0fiv0 k al, 4v5kw bacitor 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 accel:i+sob+m sh19x 9hds 1qbt 2zierated horizontally by 7.0 kV. They then pass through a uniform m2 tiq19h+ix:+z9 bsdbosh1selectric 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 of E.    $ \times10^{5 }\,V/m$

  Electrons are accelerated by 6.0 kV in a CRT. The screen is 30 cm widebc8egh0bixmi( 3 v+ o1 and is 34 cm from the 2.6-cm-long deflection plates. Over what range must the ho e(hxbmi1oi+c3bgv80 rizontally deflecting electric 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 keV of KE in moving fromq.xy/ t 2vkwl4 vedes5-w88ejdp0 n2n point A to pointql- xp ewv5eyn2s4wv.d 2 /8nj0ekd t8 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 4dgk ho15, bpc0i0a/ rt.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 surfact- ym.(iq,czb2(kje gs0 f d)de 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, nf)v; ve(q)uh electrons 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 thu)e ;n)vf q(vhat an electron would remain stationary? Assume that the electric field is uniform.    $ \times10^{ -12}\,V$

  A huge 4.0-F capacit, g0k3/ffjoda-3v i xfor has 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 24.0a xp4l c2wg kvdb5k; lc;,xq1--V battery until it is fully charged, aftbag1;qpx-lkx,v cwd5 k;c 24ler which it is disconnected 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 excee/vwq,nzbn -4bds $3.0 \times10^{6 }\,V/m$. What amount of charge can be placed on a parallel-plate capacitor if the area of each plate is $56cm^2$?    $ \times10^{-7 }\,C$

Three charges are at the corners of an equilat6q pdlh dhs2ra5z x,g( 3r3mu2eral triangle (side L) as shown in Fig. 17–30. Dete3x(qh du52 3z lrpga s6,rhm2drmine 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 is connected to a 9.0-V battery. If a piece owv 33l8 z 7:hpadzji8kivt.n2f Pyrex glas8i3 j iv2h tap8:.ldknz7 vz3ws is placed between the plates, how much charge will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizo5,oxv2ix l8 teep 4xe7ntally 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 a pot2x ioe8l te4p,vx5 xe7ential 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 capacitance iw+e:of7gy+vwag+x 3 $C_1$ carries a charge $Q_0$. It is then connected directly to a second, uncharged, capacitor of capacitance $C_2$, as shown in Fig. 17–32. What charge will each carry now? What will be the potential difference across each?

  To get an idea how big a farad is, suppose you want to make a 1-F air-filled wmfply,:mbc:o h3 veo16 7wg)parallel-plate capacitor for a circuit you are building. To make it a reasonable size, suppos:b7mw:,o fl3 m1p6weyg hoc v)e 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 el ftw11qgu58p g(sbsp1ol7hh a.x-f 8x ectric 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 pul4zu/ x- bjqlq1sed 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 ncq-hyn2 5ld,dk;yu 3 and the 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, ayn;53lu d2yd- qkhnc, nd 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 energy to soba.3l6y9 ym ;zmp0mf qme electrons in bar3a mlf q6y.p0 m9ybzm;ium 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 $-3.02V$ (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 idencv )qoyd 2rkw4byifcy*) :i33 tical $+33\mu C$ 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-diame54ws 53h/ aoklx ild.88rld ccter coins separated by a 0.15-mm-thick piece of pawdli3ckxh .8al rs 5cl8do54 /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 capacit-6yzp - -e j lm;srz*wslatki79.(saloivr :-or with plate area $2.0cm^2$ 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. Their chargesr hyy.72lt7 jh 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 placecaimwg5505 -x +7ch4fke rli md as shown in Fig. 17–35 with $q_1$=$1.5\mu C$ and $q_2$=$-3.3\mu C$ Find the potential difference between points A and B.    $ \times10^{ 5}\,V$