If two points are at the same potential, does this mean thatbu4/a0 y (f oxng*4 5qyfwunw+ no work is done in xw4auof f(yn5 g0 4/qu*ynw b+moving a test charge from one point to the other? Does this imply that no force need be exerted? Explain.

If a negative charge is initially at rest in and bs:)-7wmtvj electric field, will it move toward a region of higher potential or lower potential? What about a positivb-)msvt:7 j dwe charge? How does the potential energy of the charge change in each instance?

State clearly the difference (a) between electric uvci8*51oinl potential and electric field, (b) between electric pon 8ov5iiul* c1tential and electric potential energy.

An electron is accelerated ;*r z*vetf6ysqej3+c by a potential difference of, say, 0.10 V. How much greater would j q*e+ 6*fzyvt;er cs3its final speed be if it is accelerated with four times as much voltage? Explain.

Is there a point along thfur:vvgqs,;3byr doy7u 9.e8 e line joining two equal positive charges where the electric field is zero? Where th8yed suvy3,rv ur9:gfboq ; 7.e electric potential is zero? Explain.

Can a particle ever move from a region of low electr bemolkv3/. +cic potential to one of high potential and yet hco.ml/v+kb e3 ave its electric potential energy decrease? Explain.

Compare the kinetic energy gained by 09 s0s 4kxsfqg jof:-j)ftfyk z ::sbyt +y5b)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 equipotentialdvqc,bp/7 moft)n96 r lines cross? Explain.

Draw in a few equipotential lines in h y :m9pc,gast:qa27;-9o)eh 5dlvx o7 lwtox Fig. 16 – 31b.

What can you say about the electric;q* sf+v3 jbpr field in a region of space that has the same potq j fp3r+;v*sbential throughout?

A satellite orbits the Earth along a gravitationt(of bm qspt4omn c/25: g4,ofal equipotential line. What shape must the or(54:f 2, 4o bpomfgt cnqstmo/bit be?

When dealing with practical devices, we often ta +z on:.8j1iurop49l3 qlozyw ke the ground (the Earth) to be 0 V. If, instead, welj 4zo9ol o:p iwr.+ q3yuzn81 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 co)r e,zr4nf.r ennected to a capacitor, why do the two plates acquire charges of the same magnitude? Will this be trn.rz,r) 4efre ue if the two conductors are different sizes or shapes?

We have seen that the capacitance C de)6+ayah:2dwh a1 f mdlpends on the size, shape, and position of the two conductors, as well as on the 61 awf2 damh:ay+dl)hdielectric constant K. What then did we mean when we said that C is a constant in Eq. 17 – 7?

  How much work does the electr0h8 *eulhr gq2*2wqch.rkt j :ic 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 do2sn3q8+ acws tb63rwn in moving a proton from a point with a potenticbw 6 3st3s2wnaq8+ rnal 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 jotia grmd+yw s-:q7i56 / ucyb5ules and eV) if it accelerates through a poten5i yaws:/+ibmrg ydq t-5 cu67tial difference of 23,000 V in a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquiresb: pnjx*yxf.up hu5e 19gu9o t1 c.6rm $7.45 \times10^{ -16}\,J$ 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 rqk6 7+ab* qk+w(j2eb*qphz potential di* +qkhb(ra7qz * pewk2q +dbj6fference between them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field of4 x wzbq2x )7l6eeiar. $640V/m$ 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:2 wtl5ewg ae3svvb l(k8b:gs48xer3 connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field between two para9bet3+.k c hcnllel 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 nucleu w3 zovea12ogzddb-:( s $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 200-V power supply, are separzdr(xyc yxy.6 249ti4z s- +equ7guhp ,dj3vp ated by an air gap. How small can the gap be if the air is not to become conducting by exceeding its breakdow 3yz4 4i uy,-+7 gdjdp ep9rxvcx q2suthyz(6.n value of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an external force to move 70raezu22e g ga $-8.50\mu C$ 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 1o0rmd1l9 zdzepzpk9+5fd 47og dd n 4energy
(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:7*,,wdr5ldf lblsb bc +bo(tV?    $ \times10^{5}\,m/s$

  An alpha particle (which is a helium m8s.z jc;gpbh9:+jdm nucleus, $Q=+2e$, $m\,=\,6.64\times10^{-27 }\,kg$) is emitted in a radioactive decay with $_{KE}$ = $5.53MeV$ What is its speed?    $ \times10^{7}\,m/s$

  What is the electric potential 15.0 cm from y ;ro- osh;1rea $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates an electric potential ra/is3 is o8m-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 tl,w0n8bkcr vo(lm;i;kn0i , xnl -w4ghe shape of a football. This conductor carries a net negative chal,x- ok;vcrn w(m0, i;4i8kw gnn0lb lrge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potentj 8oia)tu-y*z ial 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 cor 2;c v;k zi7djqyd5mc8)afd a;ge6f( kners of a square of side L as shown in Fig. 17–25c;87d5 da f )vdkyqf(6j; mgck ;ia2ze. What is the potential at the fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts froifp b*1pq; dd,m 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 three electrons from a t 9ar y.(zcn9fu8:cb2 s0 )lgip4vlmrgreat distance apart to gnsrzy.i)49t0rf:b(m9lp acl v 2c8 u$1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which ia2 o6pyr2s2zi s 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 used to accelerate a prgov):5.ldjjzfcocz y8 w/3 :hoton (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 lcv,rbro )-8fd, as shown in Fig. 17–27. Determine a ,olfrv)r8cb-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 ato4,6waf hp.vrdjo( 1a bm, an electron orbits a proton (the nucleus) in a circular w 4 a6,jbap1.rodf(vhorbit 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 proton arwdc:b )vr* 7(*fmoeu gq.k)yae $ 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 dipolesvck09yok ,: x 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, con3z)1; igscx+tn/c aay sidered as a vector, points from the negative to the positive ccy3;aas+/1 ngi )tx czharge. 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 hoan;g fvr31 msz nb/ w+6uvy *:rn;c-bpld $+2500\mu C$ 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 cab+q *btmjl 2.fpacitor 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 ofa xay-avvz-2yp .-/ 3-d ribxt $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential differenj bp ji qdo64,vdp). h n)8xgj1;rx+zyce between two short sections of parallel wire in air is 120 V. They carry equal anbp4xp +jdq 1 v,r8 jjx.ozhnd;)ig)y6d 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 coyha50 f/-n cpknnected to 05 h fpa-c/knya $7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired. What area must the plates hykssgby3 ex6 (.1 jz*zave if they are to be separated by a 2.2-mm air g.*ezj6 kzs(yg3y 1xsbap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitor increa)t m-rlz xhmb5y/wh4d 3d kd)/ses 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 5gt8arnw ) i+v(emu;a $8.5 \times10^{ 5}\,V/m$ 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 opposm5pl7koly *sm* .sl -dite $5.2\mu C$ charges on the plates, and an electric field of 2.0 $2.0\,kV/mm$ is desired between the plates, what must each plate’s area be?   $m^2$

  How strong is the electric )f 8zk w.rqj+vfield 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 is disconnectv /jdje0u7/ i1de ind7ed from the battery. Whed1/7ij j/ ddeve u70inn 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 eb 76 ;gy/hsriof two square parallel plates 5.5 cm on a side that are separated by 1.8 m;g ibh r/se6y7m of paraffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circular plates with 82: .oymldqb 4sf7tpn a radius of 5.0 cm separated by 3.2 mm of mic bt.27:8pfs4nm y oqdla?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected to a 22-V battery. If a piece of mica ii 5+2entllf2y-d n-q6yrw -wss placed betweenfer 2+-t5sdlil2y q6w-nw- yn the plates, how much charge will flow from the battery?    $ \times10^{ -7}\,C$

  The electric field between the plates of0xq 2l ;j-jlqa.4f-uel:pxgr 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 capacito 7nfm/hm1f f+i32 jk+0q mebdzr. How much energy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator iqy37;s s7qaf*ggfm8zx+ r7r is used to shock a heart that is beating erratically. A capacitor in this device is charged to 5.0 kV and stores 1200 J of energy. What is its caq38r7y x7qgsz7; gmff+i* r sapacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the electric field between t:6x:vf 3eh0omlf1 u hnwo square plates, 8.0 cm on a side, separated by a 1.1 eo6fm:x:v nuf03 hlh5-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 cm apart y9m udmu 94op2j -0r leghvs9-jf-w2tand connecting them to the opposite terminals of a 9-V batteryot0j p9 9j-y m-m2uvsdh-l9r4w fu2 eg. 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 has fifuur8 ad2og:5 xed 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 changef dklq;b,f6a 2 if (a) the potential difference is doubled, and (b) the charge on each plate is dq afb62;kdl ,foubled, as the capacitor remains connected to a battery?

  A $2.70-\mu F$ capacitor is charged by a 12.0-V battery. It is disconnected from the battery and then connected to an uncharged $4.00-\mu F$ capacitor (Fig. 17–29). Determine the total stored energy
(a) before the two capacitors are connected,    $ \times10^{-4 }\,J$
(b) after they are connected.    $ \times10^{-5 }\,J$
(c) What is the change in energy?    $ \times10^{-4 }\,J$

  In a given CRT, electrons are accelerated horizontally bye1g wnjwc+)oaj5 x,x b d3(9mktj 7q*a 7.0 kV. They then pass through a unifoo a c a9edk+bw7wq31*gxjnxj)( m, t5jrm 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 of E.    $ \times10^{5 }\,V/m$

  Electrons are accelerated by 6.0 kV in a CRT. The sl. r0l9c.slc ncreen is 30 cm wide and is 34 cm from the 2. .l0c.srl 9cln6-cm-long deflection plates. Over what range must the horizontally 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 acquire o2eah/wy0p +x4b8 iyv q7wj(anef86js 6.3 keV of KE in moving from point A to point Byjyb6v(wxjofq 8a+ w4/e 7eh2i8 ap0n.
(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 cx xp/g1*,bdbcharge and 4.2 MJ of energy to the Earth.
(a) Across what potential difference did it travel?    $ \times10^{ 6}\,V$
(b) How much water could this boil and vaporize, starting from room temperature?    kg

  There is an electric field near t w2o aduah:+ty+ gh--dhe 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 accelerated by thousands of vnmh.plfa d (2qoybfsivn4 6 e(.t9u1/olts through a vacuum. If a television set were laid on 4bn o.vd2 hu(nfts/9f aqiy(1l e6 pm.its back, would electrons be able to move upward against the force of gravity? What potential difference, acting over a distance of 3.0 cm, would be needed to balance the downward force of gravity so that an electron would remain stationary? Assume that the electric field is uniform.    $ \times10^{ -12}\,V$

  A huge 4.0-F capacitor has enough stored energy to heat 2.5 kg of waterabwl+ x8-vg u2 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 fully charqmu300 x9e lfyb)4h i-yr2wacged, after which it is disconnected from the battery. A sl94wq x2ac fh y3)yiu0m-eb0l rab 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 elec,c454t zn.w, ztrwgqmxry h(5tric 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 an equilateral triangle (side L) as shn; b8*r wf fd5,qfzej8own in Fig. 17–3wfjf fq e8 z*;b8,d5rn0. 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 is connected to a ,x xu( g3wmud,9.0-V battery. If a piece of Pyrex glass is placgx u (,wdx3u,med between the plates, how much charge will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally from rest in pr dvyy4h9b5 ek/6k ,hpn+qe;a television picture tube by a potential difference of 550e;kyhv4y kpqp hn,d5b/er69+0 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 what angle $\theta$ will the electron be traveling after it passes between the plates?    $^{\circ}\,$

A capacitor of capacitanb,z /pakp q1*(m ,yogzce $C_1$ 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, sup;2v coem:zsu 3ds z00z2q ostnr2 03whpose you want to make a 1-F air-filled parallel-platdez :cs 2vn mrq3o03 ;2u0h 2sstwo0zze capacitor for a circuit you are building. To make it a reasonable size, suppose you limit the plate area to What would the gap have to be between the plates? Is this practically achievable?    $ \times10^{-16 }\,m$  ----待选择----YesNo 

  Near the surface of the Earth there is an electric fie9)7 2-u g e+ celr)z3ilqluuvzld 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 pulsed nitrogenmi oe 74,:piji laser has a $0.050\mu F$ capacitor with a maximum voltage rating of 30 kV.
(a) Estimate how much energy could be stored in this capacitor.    J
(b) If 12% of this stored electrical energy is converted to light energy in a pulse that is 8.0 microseconds long, what is the power of the laser pulse?    $ \times10^{5 }\,W$

  In lightning storms, the potential difference between the Earth and the bottom abl0c8o) oi58ug2sq v of the thunderclouds can be as higioag 8)0sb 8ov u2c5qlh 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 enough enege2h(y x71 rizrgy to some electrons in barium metal to eject them from a surface at high speed. See Fig. 17–33. To measure the maximum energy of the electrons, another plate above the barium surface is kept at a negative enough potential that the emitted electrons are slowed down and stopped, and return to the barium surface7ezry(g xi h12. 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 ni or6r 3euz1 f2v,j/7mk, cqc$+33\mu C$ 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 bhd )fuw w452.ok, dlh+z.ze:yjv8 bhpiece of pap zh2 vwd)4b.8+,jh edu 5h w:zblko.yfer $(K=3.7)$ 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 capacito8 t a:u 371nw8xnxj r,qmsa2ewr 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 f(el6(s xa rc1g p/+as,v(kyhn :ouk*gixed 4.0 cm 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. 17–n.m m56 :jc6 ossel fwq4(mv7e35 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$