If two points are at the same potential, does t,tqd+m lm,mx* i ,iw9j6j-rm ohis mean that no work is done in moving a test charge from one point to the other? Does this r* ,ot,-xwm ml9i +jmd,q6jimimply that no force need be exerted? Explain.

If a negative charge is initiallyd dx8)sx/uq80avo iv 2 at rest in an electric field, will it move toward a region of higher adq2v8xvd 8 /uo )0isxpotential or lower potential? What about a positive charge? How does the potential energy of the charge change in each instance?

State clearly the difference (a) between electric potential l/oqbi)2s h1n and electric field, (b) betwl/os)2 b1q niheen electric potential and electric potential energy.

An electron is accelerated by a potential difference of, say, 0.10 V. How much gy6qc ,sy ,:dlqic5 o, m7y6iqy33vch grc5gyylcqoym,7cs, ,3 ih6 y3dqiq v 6:eater would its final speed be if it is accelerated with four times as much voltage? Explain.

Is there a point along the line joining two equal positive charges where the el 3xty0m ri)9cbhs7k yr-/eux ,ectricxei)r,h9ktyx c/3b-70s m ruy field is zero? Where the electric potential is zero? Explain.

Can a particle ever move from a region of low electric potential to one of higkwi 7*cuqaar4 iknzlsyzdj 6)52e (8tm66 dn6 h potential and yet have its electric potential energy decrease? Expladlky c tqu6kaes 6md)a8725 rn4zjn ii6w(6* zin.

Compare the kinetic energy gained by a proton woye9. 3 ++ktfj)hfet $(q=+e)$ 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? Exp nl)blg e+g64 ( 9vp0ymvk 1;ykk/hz6vt;flculain.

Draw in a few equipotential lines in Fig. 16 – 31b.az*6 hc w(yxvto8 3bhp)a)7vd

What can you say about the electric field in a * 5tfz e8+pb wqr8yz0fregion of space that has the same potential th5+*08 prfyezf 8zbwtq roughout?

A satellite orbits the Earth along a gracq jy bevkmv/i.o6010vitational equipotential line. What shape must them. bqy 0i6/1j0cvekvo orbit be?

When dealing with practical devices,)3iwhgfw4o :izf)38tmgi x -z we often take the ground (the Earth) to be 0 V. If, instead, we said the ground was how would this affect (a) the potential V, and (b) the z))3ftg48z3iifhimx wgw -o: electric field E, at other points?

When a battery is connected to a capacitor, why do the two plates acquire charg2xz ng4t wd496:a ffb 2v7oakges of the same magnitu:z 7d 2kxofbw4t4f gan6va2 g9de? Will this be true if the two conductors are different sizes or shapes?

We have seen that the capacitance C depends on the si3u9y zck b-h8 ucpki4df r-2;xze, shape, and position of the two conductors, as well as on thz3 d2bfr8y-p- kui; 9x k4uchce 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 elecjoq ac67,c)ik tric 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 dofb*ey o,i)7pw in moving a proton from a point with a potential o 7,ieob*)wpyf f $+125V$ 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 86n5bidj,h x6e u1rig) if it accelerates through a potential hi66gx niru 5d 1j8be,difference of 23,000 V in a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires lhc/ d5gx6q+ e$7.45 \times10^{ -16}\,J$ 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 apartc)fggj4(k 1ojv 9ysr(thg1)n, n.v eo if the poten 1r(yo gts4nv (gc9).on,h1gefk) vjjtial difference between them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field ofeg6fyffw 58xb:wtbue se40(. $640V/m$ 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 to a 4,9 pgujt ;hh)y5-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field between two parallel plates connected to a 45-V w68ndo ao9bwwe0:ab4m3 -qzk battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is needed to give t)yg)wf.4*ody,7 9z/e8a s xltkcfc e a helium nucleus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 200-V power supply, + cj1jnicox )8are separated by an air gap. How small can the gap be if th)c8jji1+o cn xe 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 forod q-vnbg1 qcr9 /c ;3:n7misrce 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 an electron with kinetic energy mq *lts+k 4e7c
(a) 750-eV,    $ \times10^{7 }\;m/s$
(b) 3.2-keV?    $ \times10^{7 }\;m/s$

  What is the speed of jhbc ( v;e1w 0mn7pzqtn0*pz0a proton whose kinetic energy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (which is a helium nucleusvd2dkm59kfr/7a2j mq, $Q=+2e$, $m\,=\,6.64\times10^{-27 }\,kg$) 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 a2+zeu/ 8a rijcm from a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates an electric )p94-f vq me)bzpwcil3i.fx+ 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 football79npd3x d e;abxh r**q. This conductor carries a net negative cxa9d xdn3* e7pqhbr* ;harge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electrnif, hv)xi 92/wt wsl2ic potential 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 w /h6w;o hur7iin Fig. 17–25. What is the potential at t u7h6/riowhw ;he fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts from resti94mv)z/ d +,aba hxruy vn/s4 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 gr7:xxis :j7)ijbef1 c5p gx1kleat distance apart to b1p7 cej1xx ::)7ljsxgk 5 fii$1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is;mv4j.ruk7: ufooq2 z 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+mu*: hx dii2o 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 separa :*n kcsd4 m 1mdpk8ihcn9zs/hq+ e/7mted by a distance d, as shown in Fig. 17–27. Determiccz / 9edds1qmm+ kn*8ih s/mp kn4h:7ne a formula for $V_{BA}\,=\,V_B-V_A$ for points B and A on the line between the charges.

  In the Bohr model of the hydrogen atom, an electron orbits ay yy,/2z exm.j proton (the nucleus/jxm.yyy,z2 e ) in a 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 proton arn nmq0qz3 9comn 008ore $ 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-gg ,9p8 kpfk 1i-bydv 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, considerhg3tm3yw 3 3nnwy+yw+ed as a vector, points from the negative to the positive charge. Thty+w m+3g3 yhnwny3 w3e 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 hew0q3w7vya /g-woej7 wxln )h y 3i:v9old $+2500\mu C$ 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 7ry d3zr3osnha1q*.bb txid: 8-qh o+ $+2500\mu C$ 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 hdvh1ux m1 r m)7v7+mpgb-g /acolds plus and minus charges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference between two short sectioni 9jxxe67cdlg kw t+ez,a: (w8ny ds5/s of parallel wire in air is 120 V. They carry equal and opposite charge of magnitude 95 pC. What is gt(kw/zxnj ,dy xc:s lea+856dw97iethe capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows from each 124 nd vg0uljdterminal of a 12.0-V battery when it is connected t2d uln gjv014do a $7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired. What area must the plates have iw 8pmrgvz .c(;f they are to be separat8v(gc; z. rpwmed by a 2.2-mm air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitor incrvuwn 9 +myk*9sskk 2t6 i5f39jz 7cb71djfttjeases 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 :j,1ypyxe pw )$8.5 \times10^{ 5}\,V/m$ 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 oppn(b6,pr7iec v osite $5.2\mu C$ 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 lc mh94ouu wo+3gp9/p field 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 ba, cy;t.whnqz 7ttery (Fig. 17–29a) and then is disconnected from the;7c qth,yz. wn battery. When this capacitor $(C_1)$ is then connected (Fig. 17–29b) to a second (initially uncharged) capacitor, $C_2$, the final voltage on each capacitor is 15 V. What is the value of $C_2$? [Hint: charge is conserved.]    $ \times10^{ -5}\,F$

  A $2.50-\mu F$ capacitor is charged to 857 V and a $6.8-\mu F$ capacitor is charged to 652 V. These capacitors are then disconnected from their batteries. Next the positive plates are connected to each other and the negative plates are connected to each other. What will be the potential difference across each and the charge on each? [Hint: charge is conserved.]
$V_{final}$ $\approx$   V(Round to the nearest integer)
$\begin{array}{l}
Q_{1}\\
\text { initial }
\end{array}$   $ \times10^{-3 }\,C$
$\begin{array}{l}
Q_{2}\\
\text { initial }
\end{array}$   $ \times10^{-3 }\,C$

  What is the capacitance of two square paxi-x;.rbq 5zi rallel plates 5.5 cm on a side that are separated by 1.8 mm of pa-zxrxb.; qii 5raffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pb lyu xt6bo:rp6,j2hxm0oj1,air of circular plates with a radius of 5.0 cm separated by 3.2 mm of micmrjo0b ypxxj: 6,6tloh, 2bu1a?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected to a 22-V battery. If a pie3iemkg of0(kcz )-.md p/w6 6e-opalece of mica is placed between the plates, how much charge w aemedgmo0 ./z w6-pio)efkkpl-6c 3(ill flow from the battery?    $ \times10^{ -7}\,C$

  The electric field between the plates of a paper2 +(wlbe+ad;(cqpq r, bn eol.-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 ener85x905fs xsnlwsbf1 y gy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shock a heart that is beating erraty)v5 ; xpyr hi8(dcj9tically. A capacitor in this device is charged to 5.0 kV and stores 19yxpyd iv j;t(85)hrc200 J of energy. What is its capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the electric field between two square plates, 8.0b 0b.s yf e*,myz2 9aw9oz9rifvp7wq9 cm on a side, separated by a 1.5-mm air gap? The charges on.oe*b 0v9fy9sa 2w97 biqf m z,w9przy the plates are equal and opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is assembled by placing two 9-in. pie p9 4iskl y+dilb+71 sufc9mtd; ans 5 cm apart and connecting thefi7miykt9b sd+l d9;s l4 uc1+m to the 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 capacitorhbop t+np+05+9lazxp 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 i lp.zc3m hr72pn a capacitor change if (a) the potential difference is doubled, and (b) the chlp7phr.c2 z3 marge on each plate is doubled, 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 by 7.0/jgli0n;rhnca r 8*/c kV. They then pass through a uniform electric field E for a distance of 2.8 cm, j/rcicgal;*n0r8/ h nwhich 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. tp, /cih0+k- g c/l2 6lhcuomrThe screen is 30 cm wide and is 34 cm from the 2.6-cm-long deflection plates. Over ki2hc oc/- mg+c 6llrthu0 p,/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 acquires 6.3 keV of KE in moving jra /t athya(+0k4 on-from point A to p naryh( o +atatjk-04/oint B.
(a) How much KE would a proton acquire, starting from rest at B and moving to point A?    keV
(b) Determine the ratio of their speeds at the end of their respective trajectories.   

  A lightning flash transfers 4.0 C of charge and 4.2 MJi 0 5u74wgw8ubrs;hog 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 whose magnitude is 5neorum/;g nb* fv i00z 6)hnfabout $150\,V/m$ How much energy is stored per cubic meter in this field?    $ \times10^{-7 }\,J/m^3$

  In a television picture tube, electronse + ecr 8lr+w-v./tso24vsc ar 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 se+r+c4v wlsro/2-a. cve8 t rwould remain stationary? Assume that the electric field is uniform.    $ \times10^{ -12}\,V$

  A huge 4.0-F capacitor has enough stored energy to heat+ :relr7 o;musi 9iopz loj:u75fwh*3 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/r5ei qo .il5d;w-lrxvug83i0 ,ofl d-V battery until it is fully charged, after which it is disconnected from the battery. A slab of paraffin is then ins8 5dfreu grwlod ix 3;-lvi0 /.5oli,qerted between the plates. What will now be the voltage between the plates?    V

  Dry air will break down if the electric z y5)clr px)m/siep l b:c os178)f9ipfield 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 ( fw-rrhtu2.tp3kzd +k2qwn )zpcl6 8 +o,z1 tbside L) as shown in Fig. 17–30. Determine the potential at the mi6bh +2qwoz-8.uzzk t1 nt23lftp,rr)cd+ w kpdpoint 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 /h n1) kryk hn/z(.pezbattery. If a piece of Pyrex glass is placed between the plates, how much charge will then flow from the ky h zr.1nke)phz //n(battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizz(0u ,/pq.f kk 3mzsxpontally 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 potential difference of 250 V (Fig. 17–310,smxf u (ppzkzk q/3.). At what angle $\theta$ will the electron be traveling after it passes between the plates?    $^{\circ}\,$

A capacitor of capacitani6i cnoa263 atce $C_1$ 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-fil: rv3 .yoj24kkt /wmuxled parallel-plate capacitor for a circuit you are building.3/rtyxkmjv:4k uw2o . 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 thkoc w.wo* 0 rsnj97g+cz b+(geere is an electric 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 pulsed nitrogen lnu ++nwiry/m5 aser 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 Eart on5. c4kwv-jth and the bottom of the tn -ot4wvk c5j.hunderclouds 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, ultra ptzze:75m r8ecip+ *b7m7x z38wwslru*qd q 2violet (UV) light provides enough 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, another plate above the barium surface is kept at a negative enough potential that the emi8rz7 *emq *3r+b 2cupz ilz7stwm5p dx8 w:7qetted 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 placef9s4 ee2qon z:mj2g-ud 36 cm from 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 from two 1.1-cm-diameter c)kve+iv-n+ty wky f )*oins separated by a 0.15-mm-thick piec)ky+kw* fe) nivv+-tye of paper $(K=3.7)$ A 12-V battery is connected to the capacitor. How much charge is on each coin?    $ \times10^{-10 }\,C$

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

  A parallel-plate capacitor with plate area f4wh(e5 -q ,nyd/vu* kgf,a iu$2.0cm^2$ 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 plkp 3zn); p* h99ijzafrom 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. 17sj 0, x93 obb(/ofshht–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$