If two points are at the same potential, does this mean that no work/ + wn98elpbrax2 dkf1 is done in moving a test charge from one point to the other? Does this imply that norde91/wx bf lan2p8k+ force need be exerted? Explain.

If a negative charge is initia ow*osw*9:aru ezzeny3 3 ix(:lly at rest in an electric field, will it move toward a region of higher potential or lower potential? What about a positiax(zwo sy*:9e izow r :e33*unve charge? How does the potential energy of the charge change in each instance?

State clearly the difference (a5 v i49/aruzsv) between electric potential and electric field, (b) between elec9vv5isrua z/4tric potential and electric potential energy.

An electron is acceleryho,n3sa+wu:8 x et -yated by a potential difference of, say, 0.10 V. How much greater would itwya8+uo -3s ehx :,tnys final speed be if it is accelerated with four times as much voltage? Explain.

Is there a point along the vmoj cju)w9w,i0od3fzy) .1 f line joining two equal positive charges where the electric field is zero? Where the electric potential is zero? Expla wc)oy,fi ujd0zmfov3wj) 1.9in.

Can a particle ever move from a region of low electric f * j87 m1zlnw)iw,fnd2f9bj fpotential to one of high potential and yet have its electric ,nj* mwzdbnff78i 9wf1j)lf2 potential energy decrease? Explain.

Compare the kinetic energy gained byc z87b kt)th sz+2kqck,d2fc ) 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 lines cr(t pzw 83a81ogx aub)n dv:rj/oss? Explain.

Draw in a few equipotential lines in Fig. 12dh) 47lz0q2ci4v(y bdshk o),bglh ji7gs ,l6 – 31b.

What can you say about the electric fk+b f.f(6v: )a tfunlsield in a region of space that has the same potential thro).bafvl u fn6f(+stk:ughout?

A satellite orbits the Earth along a gravitational p87 cvidre6b ptrt8.h72 1wv mequipotential line. What shape murt m6w78v18hp.r ebi vtp2cd7st the orbit be?

When dealing with practig-j 9 zi0 t0n7gidbky2o4:liacal devices, 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 electric field E9iji dn 2z0g -by7i:o4glat0k, at other points?

When a battery is connected 7 mu r /5rayjif5qw9/yto a capacitor, why do the two plates acquire charges of the same magnitude? Will this bemwu59 iryar //7fyqj 5 true if the two conductors are different sizes or shapes?

We have seen that the capacitance C depends on the size, shape, ana: .b cj;.pjpte8fl36fl a8bj d position of the two c 388bjtlb fa;p.j:6fp jlae.conductors, as well 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 field do in moving h+;:va7*aza vqgko7a a $-7.7\mu C$ charge from ground to a point whose potential is $+55V$ higher?    $ \times10^{-4 }\,J$

  How much work does the electric field do in moving a proton from a pt oh hm w)z89m4qb, gx1bjk,t2oint with a potential ohbtjmz9 kg, m1q2ht w84xb,)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 elecj bqb:cm*p,m4 tron gain (in joules and eV) if it accelerates thro c*4qm:jmb,bpugh a potential difference of 23,000 V in a TV picture tube?
   $ \times10^{-15 }\,J$
   eV

  An electron acquires m/lgc 60h z q8uckgb9aplv((: $7.45 \times10^{ -16}\,J$ 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 parallel2pn .cly 83i2 xecuy-s plates 5.8 mm apart if the potential difference between them is 220 V?s xnu2ye -pi.cl8c3 y2    $ \times10^{ 4}\,V/m$

  An electric field of7(vftwmn , (bw $640V/m$ 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 k rc3*bcdlg ;.to a 45-V battery is $1500V/m$ How far apart are the plates?    m

  The electric field between two parallel plates connected ,u jc9pl9zc t46( yuqr7+cxwvto a 45-V battery is $1500V/m$ How far apart are the plates?    m

  What potential difference is needed to give a helium nls6bi 1mq- 8nzz4nyd,la;f m6ucleus $(Q=2e)$ 65.0 keV of kinetic energy?    $ \times10^{4 }\,V$

  Two parallel plates, connected to a 200-V power supply, arejra, p6//cx hs),; hpep1 dqpv separated by an air gap. How small can the gap be if the air is not to become conducting by exceeding its breakdown v1 ,v pr;h jpsqe/xdp6p /c,)ahalue of $E\,=3 \times10^{ 6}\,V/m$?   $ \times10^{-5 }\,m$

  The work done by an extern613mvgdm1swb cgbn3 7al 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 wit4ia quep .b17vl2nb+lh 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 evc cve r/;dn((nergy is 3.2 keV?    $ \times10^{5}\,m/s$

  An alpha particle (whichz ;qbp,si0kc g8t6a) l is 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 15.0 cm from a 0qrlmb645f q6 8jeh 8;nk 9/fhm+elzm ez7jtx$4.00\mu C$ point charge?    $ \times10^{ 5}\,V$

  A point charge Q creates an electric potential )b+j*ry10 clcm p 8sof a94q.i ke/utnjn81i vof $+125V$ at a distance of 15 cm. What is Q?    $ \times10^{-9 }\,C$

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

Draw a conductor in the shape of a football. This conductor carrie/h;7pfmj:j n5ml o2 6y8kv5i2fm ulpfs a net negative c5 2 h6ifl 5k7f8m/nm pmlj:vjyf2;uopharge, $-Q$. Draw in a dozen electric field lines and two equipotential lines.

  (a) What is the electric potential a distance of98k hxr6fa u9bqlk-r+ $ 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 atos c ef3m;3*ih6y)qin Fig. 17–25. What is the potenti)3eh ; s*cfay6oiqm t3al at the fourth corner (point A), taking $V\,=\,0$ at a great distance?

  An electron starts from rest 32.5 czm8:ixheud8 vj f /.(fm 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 don6;h5 k 7p7ocnfq bt eqhd96c1fe to bring three electrons from a great distance apart tf7hc ;pnhbqot 7qd1ek9c6f 65o $1.0 \times10^{-10 }\,m$ from one another (at the corners of an equilateral triangle)?    $ \times10^{-18 }\,J$

  Consider point a which is 72 cm nortl2b j2v9, b/x scge1fnh 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 jq/ ;9t/jygo gused to accelerate 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 separated by a distance d,zniy sv6/+5 gg as shown in Fig. 17–27. Determine a formv+ sn/6izgg 5yula 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 (the n hbu351- qho/o vogo6lucleus) in a circular orbit of radius3uoo6 bg olq h-51hv/o $ 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 prot 2rt,x2xr2uej lw,sa4g:w4ynon 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 potentby s7u4i28qm-l63xa.bz ctwz ial due to a dipole whose dipole moment is $ 4.8\times10^{-30 }\,C\cdot m$ at a point $1.1 \times10^{ -9}\,m$ away if this point is
(a) along the axis of the dipole nearer the positive charge;    V
(b) 45° above the axis but nearer the positive charge;    V
(c) $45^{\circ}\,$ above the axis but nearer the negative charge.    V

  The dipole moment, considered as a*r;hb rnbj,yz 0m8 0jt vector, points from the negative to the positive charge. The wat ;rt*8j0ry jbhmbn0z ,er 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 capak zadi 72he+p,m5c6hncitor 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 holdwfman1uw pcz)n 5 c* v9s(e7w7 $+2500\mu C$ 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 of h3pdv f6tu(q /pe3ou 6$ 16.5\times10^{-8 }\,C$. What is the voltage across the capacitor?    V

  The potential difference between twomx8vlk;r e; 2l short sections of parallel wire in air is 120 V. Thekv2em l ;;lxr8y carry equal and opposite charge of magnitude 95 pC. What is the capacitance of the two wires?    $ \times10^{13 }\,F$

  How much charge flows fr 8h;ore6 c9k9(oe0kln hdv)a bz:tmi9 1w b:dqom each terminal of a 12.0-V battery when it is connected tzn:m o:)kdwoth0b e6le;ah9 d rkv c(qi89b91o a $7.00-\mu F$ capacitor?    $ \times10^{-5 }\,C$

  A 0.20-F capacitor is desired. What area must the plates have if they are to ok8ipao2/vfd 54+lp ube separated by a 2.2-moka+l4of 5p dp uv2/8im air gap?    $ \times10^{ 7}\,m^2$

  The charge on a capacitor increasew3.q8 rx8yq . xwpv+fes 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 of4kxc h5;b8x q qi+o.;keaoba9 $8.5 \times10^{ 5}\,V/m$ 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 oppo eytp/saf) ;q8site $5.2\mu C$ 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 fi5k/lir/o d..;c c yjxeeld 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- ;gno8qxbw t5 125-V battery (Fig. 17–29a) and then is disconnected from the battery. When this capacitor qx-w tb8 no5g;$(C_1)$ 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 par6,i i,vw ;n tfud0zz8zallel plates 5.5 cm on a side that are separated by 1.8 mm of paraffiwtvzdn8z,i if0,6z ; un?    $ \times10^{-11 }\,F$

  What is the capacitance of a pair of circular plates with a radiusg6 *trc+- zwhu of 5.0 cm separated by u twh-+6zcrg* 3.2 mm of mica?    $ \times10^{-10 }\,F$

  A 3500-pF air-gap capacitor is connected to a 22-V battery. If a piece of84*zj 3w .( :dcs qrk zgzlna*uk*p+qt mica is placed between the plates, how much charge will flow from the battern u rqjzz8c4k3*wgp ld.:+*( zstqka *y?    $ \times10^{ -7}\,C$

  The electric field between the pli 70f x vdht,ypta3-)cates 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 ener*q b- fx6*cb3 ziw . f4iebo/nk5-giyjgy is stored?    $ \times10^{-4 }\,J$

  A cardiac defibrillator is used to shock a heart that is beating er+s dw3ya5;e byratically. A capacitor in this device is charged to 5.0 kV and stores 1200 J of energy. What is its capd5sy ye;wab3+ acitance?    $ \times10^{-5 }\,F$

  How much energy is stored by the ele/bq (lws) n5bnctric 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 opposite and of magnitude 5qblwn ()/nbs$420\mu C$.    J

  A homemade capacitor is assembled by placing two 9-in. pm (p s:ks)ajnes6:p a1ie pans 5 cm apart and connecting them to the opposite terminals of a 9-V battery. Estimatee asn)(:m: s61 jappsk
(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 fixed cp(b ;sb9 mn ya)g5x7riharges $+Q$ 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, qxm5wcw *p3n)a/ivh ) the potential difference is doubled, and (b) the charge on each plate is doubled, as the capacitor remains connected to ax/ ,)35awhn* cm iwqpv 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 acce 76 e1pu+jzk j7-m+laa pp0vvclerated horizontally by 7.0 kV. They then pass through a uniform 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- 7vevm6zj7aa k+pclu10p+jp .    $ \times10^{5 }\,V/m$

  Electrons are accelerated by 6.0 kV in a CRT. 4trxn0d.ndbpd0rp+hym cu 6vu. 1o+;w-8z fqThe 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 fielwm4.dpt+c16nn0.-u 0ddu 8rbzo rfv; y phxq+ d 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 j.53kbsc:gxf KE in moving from point A to poib jsgkc5:. xf3nt 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 Md*h,bpn 24lue07 cywxJ 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 fjmo q 769geb3yield near the 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 bf:(tqvp 1i lyfsqw6ms7h;8 5cy 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, wsqhf6i sm;v1lq57:tfcp8 yw (ould 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 kgq/w/uo(-gh/ so(j/ez )4c sin sx/o;mft mgq ( 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-V battery until it is fullj lp+xll h oz55n/y4v i -+u6mmrbe5z:y charged, after-zuv ix5ybhz46n:r l+jo/mm 5el p+5 l which it is disconnected from the battery. A slab of paraffin is then inserted between the plates. What will now be the voltage between the plates?    V

  Dry air will break down if the electric field exceijtd( no-/a, g 6h;outc9r,hmcc8y,d7 if:hoeds $3.0 \times10^{6 }\,V/m$. 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 tdr lc:rv,/,.3esikf/vra/ dequilateral triangle (side L) as shown in Fig. 17–30s:3d idrlrtca,/ek/vf,./ r v. 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 arp naq 2u)9,poe. qhnegb-8i : 9.0-V battery. If a piece of Pyrex glass is placed between the plates, how much charguqb2 eon)r g,9qh.:pn -ae8ip e will then flow from the battery?    $ \times10^{-8 }\,C$

  An electron is accelerated horizontally from rest in a telev+ t+ielk749*k7zulk03 np kw/p ekjbtision picture tube by a potential difference of 5500 V. It then passes between two hor*kn+ 7k pl0 ztlk7 wbj/93ikekuep4+ tizontal 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 capacitance0 +uyht ;m.awp $C_1$ 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, suppcwn8ie fo. lk0d/406taio jh3ose you want to make a 1-F air-filled parallel-plate capacitor for a circuit you are building. To make it a reasonablenfoo0c/3w idl4h.ate68i kj 0 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 th0(x ,l* r.ovl6,lilk po gahj/ere 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 nitroge3ict2yhyv+;q 0v) by dnv.-l tn 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 be 6i +s+ (qclqqe1yenk9tween the Earth and the bottom of the thunderclouds can be as high as 35,000,000 V. The bottoms of the thunderclouds a1qis 69qcnke y+( e+lqre 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 c9gk909d yq k aw5uk0k* yh.loprovides 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 emitted electrons are slowed down and stopped, and return to the barium surface. 5 w9 okdk yyg0l0q hau.kk*99cIf 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 cl1 l2x*zz*hy bm 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-diamcqwdq1:)gf 9heter coins separated by a 0.15-mm-thick piece of papef 9):wq1hgdcq r $(K=3.7)$ 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 capacitotiuvjn5032l -v* y0ee e4t kq4gbcso4r with plate area $2.0cm^2$ and air-gap separation 0.50 mm is connected to a 12-V battery, and fully charged. The battery is then disconnected.
(a) What is the charge on the capacitor?    $ \times10^{ -11}\,C$
(b) The plates are now pulled to a separation of 0.75 mm. What is the charge on the capacitor now?    $ \times10^{ -11}\,C$
(c) What is the potential difference across the plates now?    V
(d) How much work was required to pull the plates to their new separation?    $ \times10^{-10 }\,J$

  A $2.5-\mu F$ capacitor is fully charged by a 6.0-V battery. The battery is then disconnected. The capacitor is not ideal and the charge slowly leaks out from the plates. The next day, the capacitor has lost half its stored energy. Calculate the amount of charge lost.    $ \times10^{-6 }\,C$

  Two point charges are fixed 4.0 cm apart fro4 c;1inygub4 y;n u*uem 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 sho61j f6hhdx .s)of:bxp wn 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$