If two points are at the same potential, doesl xba wl7,t:hqu +r (yh*/.rzm this mean that no work is done in moviyth,+r7 lxwmr.h au*b(l/q: zng 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 an electri ;ca8 7dlb(cxic field, will it move toward a region of higher potential or lower potential? What about a positive charge? How does the potential energy of the charge change in each insta 7acilxd (;c8bnce?

State clearly the difference (a)s2tvqcxc z q)wt9896u between electric potential and electric field, (b) 6 qsvxz9 qt29) uc8tcwbetween electric potential and electric potential energy.

An electron is accelerated by a potential d)9+cem *gv9nhy gec4qifference of, say, 0.10 V. How much greater would its final speed be if it is accelerated with four times as much voltage? Explaie) mhv4q+c ygngc9*9en.

Is there a point along the line joining two equal positive charges wher;tf9xv bpbr)cr k/ *(e: iyc1,dz.ow ke the electric field is zero? Where the electric potential is cy ed ft(9*r pbwzckokvbir.),/x:1; zero? Explain.

Can a particle ever m8/ z0tepewux 5y 81*thyhocpge 8 +i.hove from a region of low electric potential to one of high potential and yet have its electric potential energy decreasxt8 p*czeioge5uyph8. we+8 hy1 h0/t e? Explain.

Compare the kinetic energy gained qci /u ih ;mipo-/;cdim+oc+: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 linesq x: bdvh0jk5+ cross? Explain.

Draw in a few equipotential lines in Fig. 16 – jp +x3xoj s-xs, 56bs6j*vjg d31b.

What can you say about the electric field in a region of space t99/lhmiq-z b mhat has the same potential throughou9m-/lhzq i9mbt?

A satellite orbits the Earth al( p+ld4;r6owvrsqii /ong a gravitational equipotential line. What shape must qwr6sp4r; (io+lidv /the orbit be?

When dealing with practical devices, we often take thebzkyy xd2a:e w y /ffay2/892z ground (the Earth) to be 0 V. If, instead, we said th2 k:bfez8yz/a2 w /ydfa2y9xy e ground was how would this affect (a) the potential V, and (b) the electric field E, at other points?

When a battery is connected t2qkn x8yp .6q7qfzq4n o a capacitor, why do the two plates acquire charges of the same magnitude? Will this be true if the ty 7qxqpkq2n fnq.8z4 6wo conductors are different sizes or shapes?

We have seen that the capacitance C h19hkl .v/fnt depends on the size, shape, and position of the two conductors, as went1 k.9h/fh vlll 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 f9a9b a gm, )3022h ihdtcfhahhield 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 dq4v lln6qo4m 1o in moving a proton from a point with a omq lv4nl61q 4potential 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 elxvi- )jl.;up1hp*2m.ul b h accelerates through -l1 u.il;pxhh bvm)*e2p j l.ua potential difference of 23,000 V in a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires n)n1xmm : blag39*o 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 field3x/0 93fl tid(/ cpljhkvzgj- between two parallel plates 5.8 mm apart if the potential difference between dx 3j-thkl/pj3vfgzc 0(9il /them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field of vt92;, ehxx+3x;: nr wycpdkc$640V/m$ 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 :ahfm1q)4a, 0wnuzx0(f .h4xkcn z utto a 45-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field betwee w2w mfcmq,8csrx:)tq::;ck in two parallel plates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is needeapt ep*46o d6u4 si9k/qt0 kesd to give a helium nucleus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 200-V power supply, are s 6a,pr ck*dbitl/n;2f eparated by an air gap. How small can the gap be if the air is not to become conducting by exceeding its breakdown valua k/2ci rn6*lpftd, b;e of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an externa gpf4u;*xfhw *3i8p bnjt0/enl 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 an electron with kine5 pjz -iif+.fjtx9u( mtic 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 n.-u q, 3o cy/ah*jsxkenergy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (which 3d lwlthd2d+g.i.i ah( 9;m. g9fl zdsis a 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 potential 1h0/nd8d9 c dz u5hcz;b5.0 cm from a $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates ,ys1vwy s3mr7 an electric potential of $+125V$ at a distance of 15 cm. What is Q?    $ \times10^{-9 }\,C$

  A $+35\mu C$ point charge is placed 32 cm from an identical $+35\mu C$ charge. How much work would be required to move a $+0.50\mu C$ test charge from a point midway between them to a point 12 cm closer to either of the charges?    J

Draw a conductor in the shape of+4(x mm nuhg8x53kpu l a football. This conductor carries a net negative chxph3(lk8u mn+gm4xu 5arge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potential a dishqr-r0xxt.gudu9gb 4mcf: ) 4tance 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 i hzo r1dia*6kwjv3w8jx;i5. dn Fig. 17–25. What is the dwhk6 o.wa1zj;53vi * rjxi8dpotential at the fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts from rest 32.5 cm frox,3 :rk+lpo;zf xpam)m 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 pgjsc wu)9y ).electrons from a great distance apart to 9 .u)) gjyswpc$1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is 7vc c2-:q)o w4ud)oupg2 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 proton (radiuxj ioesa/3(:o s $1.2 \times10^{-15 }\,m$) 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 tp w ovf0,2gkk1mp;i 95gkea 5separated by a distance d, as shown in Fig. 17–27.gw02,vo5k;kp pgmft 5 9aeik1 Determine 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 a proton (thezh840 cmdh+4 zkj;wfs nucleus) in a+s hhk4 4fj8z dmwc0z; 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 ax3fx4 vo4hia xl50a6n mg(,vere $ 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 dipole whose dipole mc7 :wv1xgsnk2 p,6 revoment 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, c *m8g.9o nhdzjonsidered as a vector, points from the negative to the positive charge. The water molecule, Fig. 17–28, has a dipole moment which cajgd . mnhz9*o8n 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 fk84y/2 aoxfx 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 h qoankcij;.*r)eqmlc2b9 /bw.: hu9 mold $+2500\mu C$ 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 oqhztg a8 (5(iz:y 4d u*,kcuoholds plus and minus charges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference between two short secch t;8 qt1)ifv*d x6x9(t r oo)r:xidmtions of parallel wire in air is 120 V. They carry equal and opp:x;xov)cto*t x f( hid91 ) r6qirtm8dosite charge of magnitude 95 pC. What is the capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows from each terminal oi squ:1ju:d l8f a 12.0-V battery when it is connected to a qls8 i:j1u: du$7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired. What area must the plates have if t*m-n x9u,tniu hey are to be separated by a 2.2-mm aixtnn* 9uium-, r gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacihbeekeph h4 e:u)l.(*tor 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/) hkig9u3xom $8.5 \times10^{ 5}\,V/m$ 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 opposite r.b+(ym 3:uii: b on/uf)nbtp$5.2\mu C$ 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 tbiofs m1 ,p g4/.sm05l q0npvbetween 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 disco1 ysc-i3cvg+annecte-vi sc+3 gay1cd from the 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 parallel plates 5.5 cm on a side t+g aqvfxpj5c jj((:d/5+ gn8hz*zzwu hat are se zwg8 f(:hj5p* nvjzdax/+5j cg+ uzq(parated by 1.8 mm of paraffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a p)fqzxrz w3q;)yn: ;noair of circular plates with a radius of 5.0 cm sepa );zwz3f :q xryon;)nqrated by 3.2 mm of mica?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capsa*i .jqko p(:acitor is connected to a 22-V battery. If a piece of mica is placed between the plates, how much charge will flow from thk.p( qi:o*a jse battery?    $ \times10^{ -7}\,C$

  The electric field betwctx*dk8j61om: agem 9yf3an. een the plates of a paper-separated $(K=3.75)$ capacitor is $ 8.24\times10^{4 }\,V/m$. The plates are 1.95 mm apart, and the charge on each plate is $0.775\mu C$. Determine the capacitance of this capacitor and the area of each plate.
   $ \times10^{--9 }\,F$
   $m^2$

  650 V is applied to a 2200-pF capacitor. How much energy is h(+ qdt(hr d 2qkvl,.ostored?    $ \times10^{-4 }\,J$

  A cardiac defibrillah+8 xxw7llxg/gs j44ctor is used to shock a heart that is beating erratically. A capacitor in this device is charged to 5.0 kV andx8j7+c4 4 lhxggw xl/s stores 1200 J of energy. What is its capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the h1q g7 *o s h+acrw:./6.pdlkoszc7nfelectric field between two square plates, 8.0 cm on a side, separated by a 1.5-mm air gap? The chao hc:h/ss.qnfc7 .la 1wg* 7r6kzo+ pdrges on the plates are equal and opposite and of magnitude $420\mu C$.    J

  A homemade capacitor is assembled b.+dgnp*cex ijk xnsd76g7s3 6y placing two 9-in. pie pans 5 cm apart and connecting them to the opposite terminals of a 9-V battery. Estisgng7+x73p *i dn66 ekdsjcx .mate
(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 )5 34(x2ywqjvl u-f(a jdjo-hctwt- ho g2t)r 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 capacitor2e sjxa: :9dbwu7iew6 change if (a) the potential difference is doubled,9aj: 7 uwwi6se:b xe2d and (b) the charge 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 7.0u;a -ect e7+v5w dxradc5qk 87 kV. They then pass through a uniform electri7 7e-rua +x58qdc5;kaw t cdvec 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 qn)q oaw) m zjc9wnb,3d2k8e7CRT. 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 f,wmea 7 qnn )j32d bw8q9oc)zkield 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 from point Am( -ic 8/ mebxz+jcrrmcguc eb925q8- to m5 c9(8xe 2jcbrmez cmirgcq-b8u+ -/point 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 a) sif k*hy4t1jr.rcmy7 1c)f*zlg6qqnd 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 the Earth’s surface whoseuwg,4*q:+jva p:xsm*w1 jbq n 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 vol uswa. ;o8qsgb*q1 y(qts through a vacuum. If a television set were laid on its .(g81yws; qaq*b squo 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 water from *ukk 03p p z6qax4tcz621$^{\circ}\,C$ to 95$^{\circ}\,C$. What is the potential difference across the plates?    V

  An uncharged capacitor is connected to a 24.0-V batter4mr5sm+.e gejw0 h2cqy until it is fully charged, after which it is disconnected frjr. 2 gh4w emq5cs0+emom 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 ele28yl+rkng-h q mhlc5c b.v,0 gctric 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 (side1cenl,bm 5 2htw18suc L) as shown in Fig. 17–30. Determine the potential at the midpoint of each u28wle snch11m5 cb,tof 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 4v7xhc cpy2at m *uw5udi:8. rbattery. If a piece of Pyrex glass is placed between the plates, how much charge will then flow from dahr25 *py8 v uc 7mcix4:.utwthe battery?    $ \times10^{-8 }\,C$

  An electron is accelerated ho 7 mkt2l+ )x7b(jdesgkrizontally 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 b7kl )sed x7kj t+2(mgand 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 capacitanck t+9v b9*9auvvijd n/e $C_1$ 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 fa ,w: mxg/h)ykfrad is, suppose you want to make a 1-F air-filled parallel-wm/yk ), :xhfgplate 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 t+v9nd dc c(:cldwl g0.ypt8 s-here 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 nitroe9 yia 4k( h9uxtt,, bj)5qanzgen 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 o-ot (pqi19hpwsd4;8v n0slu pf t9pq8;4opvtld(hn u-ps10is w he thunderclouds can be as high as 35,000,000 V. The bottoms of the thunderclouds are typically 1500 m above the Earth, and can have an area of $110km^2$ Modeling the Earth–cloud system as a huge capacitor, calculate
(a) the capacitance of the Earth–cloud system,    $ \times10^{-7 }\,F$
(b) the charge stored in the “capacitor,”    C(Round to the nearest integer)
(c) the energy stored in the “capacitor.”    $ \times10^{8 }\,J$

  In a photocell, ultraviolet (UV) li2 h. kjrwuvcm d6;u)3a,cxe( ight 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 thejmcuck2,ed (; w)hiuv63 xar. 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 e9d0pmfl1mg-.l* bg uan 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 coins separated by ,bq bkki1*70mf:czcwudc + /ca 0.15-mm-thick pifc7c1w,k qm+dbkcc u/ : bz*0iece 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 platecnu0vm)2 e cy9 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 charges aky1 icxl k ) 7jbl//cq*gm(+9mt/5hhli2sec xre $Q_1$=$Q_2$=$5.0\mu C$, 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 shownk)ayn//x z* u/qqbh by3s7xw - 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$