If two points are at the same potential, does this mean that no worcd9*wxv*p s j 54wewp+-p, bcsau y8m)k is done in moving a test charge from one point to the other? Dy*p,mdw8p p w bwc9e5 s)u*ac+4 jvx-soes this imply that no force need be exerted? Explain.

If a negative charge is initially at rest in an electric field, will it movli llf(ougu *t1r307hn* xve 2e toward a region of higher potential or lower potential? What about a positive charge? How does theeurl* lt xv l3iog 7f1(2*n0uh potential energy of the charge change in each instance?

State clearly the difference (a) between elec; kqbgmphg ,-4tric potential and electric field, (b) between electric potential and mg,;gq h-p4kb electric potential energy.

An electron is accele0bsrpuj ,7y 6 8tmv*nurated by a potential difference of, say, 0.10 V. How much greater would its final speed be if it is accelerated with four timubtusp* rvjy86 m,0 n7es as much voltage? Explain.

Is there a point along the line joining two equal positive charges where the f7 p:)uik7roxelectric field is zero? Where the electric potential is zerou :i7kfxp 7r)o? Explain.

Can a particle ever move from a region of l,z5/poaeo x9gugn3 8 jow electric potential to one of high potential g ,8o3pgaexojz 5n9/u and yet have its electric potential energy decrease? Explain.

Compare the kinetic energy gained by a prpjy-r lwz1:y: yp9qa sa8x d-5oton $(q=+e)$ 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 c7i:qu 8r pyyg 2**b;iosae -zoross? Explain.

Draw in a few equipotential lineheguz. b;+v /js in Fig. 16 – 31b.

What can you say about the electric field in a region of space that has the sl:vow0o2kja-4(lhpa ame potentijlaa 4 owph(ov0kl2:-al throughout?

A satellite orbits the Earth along a gravitational equipotential line. W01)mespe xq d u3s0xw t,fe;p/hat shape musexq,w1 0;up3ese dfsmt p 0)x/t the orbit be?

When dealing with practical devices, we often take the ground (the Eartz o: 9va c4qm. 2os9v;,aqhpanh) to be 0 V. If, instead, we said the ground was how would this affect (a) the potential V, and (b) the electric field E, pz;qnv 4v o92sq9c:aam.,ao h at other points?

When a battery is connected 585v5aj -jqyp9v xenwto a capacitor, why do the two plates acquire charges of the same magnitude? 9- pv8 xj5an5jw5v yqeWill this be true if the two conductors are different sizes or shapes?

We have seen that the capacitance C depends on the size, shape, and pog/g qj+n)vorrxz-+k : sition of the two conductors, as well v+j )r:+xz ng /oqk-rgas 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 field do au lw;ibv87m;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 .1wa hxn ou.0sproton from a point with a potential oo1 .xnu0hsw a.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 a5txj8htzfr vi--7y mv1* 3ylky0r v1gnd eV) if it accelerates througihv-l*g f-1ty51y3 jtz xymrr 7v0kv8h a potential difference of 23,000 V in a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires y9o89 * /i /dgy zk)p8dbjmupu$7.45 \times10^{ -16}\,J$ 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 plateey;9u5u+ thf ts 5.8 mm apart if the potential 9uh+t tu5e;yfdifference between them is 220 V?    $ \times10^{ 4}\,V/m$

  An electric field oflic*qi+*4+4 uoin h gl $640V/m$ is desired between two parallel plates 11.0 mm apart. How large a voltage should be applied?    V

  The electric field between two parallel pgg)auwdtf+ )5lates connected to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field between two parallel plates connected to a 45-V batterh.b 16gppqxu 3y is $1500V/m$ How far apart are the plates?    m

  What potential difference is needed to give a 7-0 51bv 7ddyqnt msiwhelium nucleus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 2az0gl,ikwb 3ke88 vo3iwv e5w 4;ull+ 00-V power supply, are separated by an air gap. How small can the gap be if the,el 4ui 8l80o+lvwigk3 kabz ; ew5w3v air is not to become conducting by exceeding its breakdown value of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an external force to move6n9..0 y3yoma ybhmuk 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 withpi: t3bplao 4)j7 cu9s 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 energ-t 42h:mx iq(b i0dtdpy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (which is a defnms( z:u ,hc:+-r 6rqf4o 8x oros5helium 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 xdjk 6hks +* ,.dsa(xt. mbc8qa $4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates an electric potential ofr1:bwk5z zfwwq u dd4emr-77;pp:9t f $+125V$ 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 k d r4zr0:y)y7zd:cl pe .mpf*of a football. This conductor carries a net negativyr rz 7.ly*pd)cfp:d0 km:ez4 e charge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electrita 9c5x* e*e70w f jl89vmkgnlc 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 corner) i0qyd85nb k 3c,aodas of a square of side L as shown in Fig. 17–25. What is the potential at the05yid, dcbq8a3)n a ok fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts from rest 32.zrbk4i 8 /n nv9z0;ntn5 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 thryn :dm1vfr:st8.em 3 gee electrons from a great distance apart to m::ge3f8ntr.1y m dsv $1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is 72 cm nooc2ak2-jjq -c 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 (r 0aju6aj+04 pzkfsr/l.xd ex2adius $1.2 \times10^{-15 }\,m$) 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 s fmz0 e2wk2qi0ur(ox6hown in Fig. 17–27. Dewoq2rz60k(e i m 2ux0ftermine 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, tmwz e*pph7tm19ey+2cb 6zx electron orbits a proton (the nucleus) in a m ymh *c ,p1p2bezw76x+z9t etcircular 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 protonqazsh9njvc0 x(y s)d:h5h ky.l m4*6l 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 potential due to a dipole whose dipole moment prfx 6+pu p/y*o.n4pf- mle:jis $ 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, conmcy) 1t ehe6/qsidered as a vector, points from the negative to the positive charge 1m)6eqcythe/ . 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 capcy )ba*t7jk uq80bfj-acitor 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 capacit 6z.c-msg e 1 4n7x hbiq+:pqmtxsu+(bor 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 jg o5iz :5wz(m; mwi-rholds plus and minus charges of $ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential differ s+)qf81f fxjqence between two short sections of parallel wire in air is 120 V. They carry equal and opposite charge of magnitude 95 pC. Wh)f+j xqqs1f8 fat is the capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows from each terminal of a 12.0-V battery n0;le(cfu3 j9:)sur 7t uib;dsv45flxk: jqowhen it is connecteu)73 c;tsffs xrbju;0d:qk o4l5vl ni(u9ej: d to a $7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired. What area must the plates have ifhvxarvcka u1 w.6 (l8; they are to be separated by a 2.2-mm air gap? 8v( 1ra 6cv.u;xa lwhk   $ \times10^{ 7}\,m^2$

  The charge on a capacitor incdss , km6/p*pqf7a-u3q mnvo i:p-,)kpln9o g reases 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 ;*;sjse c l18rxgbcs )$8.5 \times10^{ 5}\,V/m$ 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 oppopgs1o ;f)9fx l8hgp )i) zt*pusite $5.2\mu C$ 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 fi qedng 9evq l lrx*qjj9f pq;t 7t4,446d0ep,deld 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 (Fiv:*6 rbfscx.dg. 17–29a) and then is disconnected from b.rc d :*vxsf6the 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 a z njkfo 6ud zmqs:/4-u3c)u8that are separated by 1.8 mm oonz4j kzm:8 6) suduuqc/-3aff paraffin?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair ofzor 1d7u/)s ;l atr 9n(flrlbc7.hh8a circular plates with a radius of 5.0 cm separated by 3.2 mm of micr 7arcuh18 a/ r.ot(s9lzflnlh );7 dba?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected t)z wo sd4b;ii0v1lv8 ;ha8xvto a 22-V battery. If a piece of mica is placed between the plates, how mu08vt;1vo4 lsvda8xh;)iz wi b ch charge will flow from the battery?    $ \times10^{ -7}\,C$

  The electric field between tcr6d* j;0sn lwhe 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 muchnw- of 2pch10 x3gdc/j energy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shock a heart that is beatingt7 *rchk.xf lv3lmn 706-nre h erratically. A capacitor in this device hm ve77 t*nlh60nxckr -f.3rl is charged to 5.0 kV and stores 1200 J of energy. What is its capacitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the /m- ;4d:bfmhzqp /i. dhdz.wqelectric field between two square plates, 8.0 cm on a side, separated by a 1.5-mm air gap? The charges on the plates are equal and .df;.pmbq h/ d-h z /zm:q4iwdopposite and of magnitude $420\mu C$.    J

  A homemade capacitor is ass2n0omqs ch4we 9n4 tp54/sowvembled by placing two 9-in. pie pans 5 cm apart and connecting4w5t4s4hqoe2/n cnp s v0o9 wm them 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 capacitor has fuq: *dkdtbf 35ixed 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 poten f0u25wow)sbf tial difference is 0 ubfw) swf5o2doubled, 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 ,m1qtofiv btn+ql6q 8zr0+m 4are accelerated horizontally by 7.0 kV. They then pass through a uniform electric field E for a dimt+4 lqfqv1 0bmz 6rito8qn,+stance 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 wide a,,,t 0elflt rrb -zbl io tebsk.8+5n*nd is 34 cm from the 2.6-cm-long deflection plates. Over what range must the horizontally deflecting, * l5-eb ten+,8ikrbrs0olzt, t.lfb 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 froqc5du 7ti 64swm point A to poicwdt4q s76iu5 nt 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 MJ o lhac,tqfthn vo9vqk. y5. /u76k pw1(f 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 whosay,z9z r/q7jga6hze 7e 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, electroxj64 ir/,jwn ons are accelerated by thousands of volts through a vacuum. If a television set were laid on its baj4 ,i wxn/r6ojck, 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 watsjb9 s3* q-lgcer from 21$^{\circ}\,C$ to 95$^{\circ}\,C$. What is the potential difference across the plates?    V

  An uncharged capacitoc.2lw lz/wa* e-t0 mamr is connected to a 24.0-V battery until it is fully charged, after which it is disconnected from the battery. A slab of paraffin is then inserted between the plates. What wiamtl 2ae*wz/0c-l .wmll now be the voltage between the plates?    V

  Dry air will break do 8md rojv)be-:kg qp3lpy4ibx1w )/f;wn if the electric field exceeds $3.0 \times10^{6 }\,V/m$. What amount of charge can be placed on a parallel-plate capacitor if the area of each plate is $56cm^2$?    $ \times10^{-7 }\,C$

Three charges are at the corners of an equ/ ms8xtlt9 ol(ilateral triangle (side L) as shown in Fig. 9/xts ml( 8otl17–30. 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 9.0-V battery. If a piecp ( ;1 z.a:oufzup- +su;gb62dt6oz3by x qzoce of Pyrex glass is placed betwsg(ay2p1xzu3- c uq pzouzo6;b6tdbf.: +o ;zeen the plates, how much charge will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated lt:w2q7+w pjkhorizontally 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 alw+j:w7 q 2tkppart 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 capacitancewf0nf2 1c vbg/-io*zr $C_1$ 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 mabw jev3z3h5m 1ke a 1-F air-filled parallel-plate 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 achievhej3 51mbwv3 zable?    $ \times10^{-16 }\,m$  ----待选择----YesNo 

  Near the surface of the Earth there is an electric field of abog e,w0tf9wuw 4ut $150\,V/m$ 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 lag233t7onp 8 pzz huwh,ser 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 theh,aw pgppq/a701 f sh 1w*op.e Earth and the bottom of the thunderclouds can be as high as 35,000,000 V. Thef0/h,o*pahs . gw11 e7wapp qp 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 7fmr. 5+8ixpzyaiq9gn y/1aj (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,r+ g791 maynjpfix i/85yq.za 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 3b*bs gxl gu2u78vy 8eks::o-q6 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-diawgvj,vmye s w*7*u9 f z)rk+9ameter coins separated by a 0.15-mm-thick piece of paper j9 emv*uz+*7ks),ywr af9wv g $(K=3.7)$ 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 az(:j9t wg( zwirea $2.0cm^2$ 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 e1fr uluydb*9e 49(bhfixed 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 F.e 8 pvi2l7jzsig. 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$