The electric field iei *f .yh;s2:fw zspn)n an EM wave traveling north oscillates in an east–west plane. Describe the direction of the magnetic field vect*;h: 2ze)pif nsfys.wor in this wave.

Is sound an electromagnetic w,w:tu oqd8 9aoave? If not, what kind of wave is it?

Can EM waves travel through a pqe41wmrj ju-xgdnz6.z k ;91rerfect vacuum? Can sound waves?

When you flip a light switch on, does m f;*tx u:rgxl0 7ntx(the light go on immediately? Explain.

Are the wavelengths of radio and television signa9ce7rjs*6-pjly* fnm ls longer or shorter than those detectabcf67jyep* * m 9snrl-jle by the human eye?

When you connect two loudspeakers to the output of a stereo amplifyvb+f7vtx : m,ho1 zn9ier, should you be sure the lead-in wiresh:bxt 7 vmz, n+vy9f1o are equal in length so that there will not be a time lag between speakers? Explain.

In the electromagnetic spectrum, whmvko2r s( y66 sgifqzyyp 9/x:u114rqat type of EM wave would have a wavelength of o6 rqvssq9g p1yk m:f1zu4i/( 2y6yrx$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound waves (2;otf9-jnc c al d: .yjz2y0e:h0 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on the same carrier frequency? Expla 0;xz9jsk ll h+;2eb(p-my hohin.

If a radio transmitter has a vex/fs; g,dniz,rtical antenna, should a receiver’s antenna (rod type) be vezi f;/g,sd,xnrtical or horizontal to obtain best reception?

The carrier frequencies of FM broadcasts are much higher than for AM broadcastsqcdl,7w, .1 qf+drfdr. On the basis of what you learned about diffraction in Chal wqrdq.1f7,c d d,+frpter 11, explain why AM signals can be detected more readily than FM signals behind low hills or buildings.

Discuss how cordless telep6 q. (u9i t .lb:8ti2sgjuisgvhones make use of EM waves. What about cell phones?

A lost person may signal by flashing a flashlight on and off cmcl3dj/)3 oqur: qbk,t /5xv using Morse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequen3:bok/d/,m5cj3ul qc q) tvxrcy of the carrier, approximately?

  At a given instant, a 1.8-A current flows in the wco -e,b8ms0 qsires connected to a parallel-plate capacitor. What is the rate at which the electric field is changi-ceb m08s,qo sng between the plates if the square plates are 1.60 $cm$ on a side?    $\times10^{14}\mathrm{V/m}\,\cdot \mathrm{s}$

  A 1200$-nF$ capacitor with circular parallel plates 2.0 $cm$ in diameter is accumulating charge at the rate of 35 $mC/s$ at some instant in time. What will be the magnitude of the induced magnetic field 10.0 $cm$ radially outward from the center of the plates?    $\times10^{-8}\mathrm{~T}$
What will be the magnitude of the field after the capacitor is fully charged?   

  If the magnetic field in a traveling EM wave has imgyg5mx(yi hd,u z)(mx- t0 7a peak magnitude of 17.5 $nT$ at a given point, what is the peak magnitude of the electric field?    V/m

  In an EM wave traveling west, the B field oscillates ,+jml g 3cve/l4u 3q.dki;3ng;wtqjv vertically and has a frequency ofjgi3nw4qe;dtq3m, k;3v+ lvc l. / jgu 80.0 $kHz$ and an rms strength of $6.75\times10^{-9}\mathrm{~T}$. What are the frequency and rms strength of the electric field, and what is its direction? (Fig. Below)
frequency    kHz
$E_{rms}$ =    V/m
direction  ----待选择----horizontal north-south linehorizontal south-north line 

  What is the frequency of a microwave whose wavelengd o:cy 2mz+v9qth is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of zun *0g q+kf4da $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has freque7s:pr0vddf l.7iq09y p. isuency $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelengl ;yd+vni7n- oth of 650 $nm$. What is its frequency, and how would we classify it?    $ \times10^{14}\mathrm{Hz}$  ----待选择----visibleinvisible 

  How long does it take light to reach us fhwl2i r0kj fa4/b+9yjrom the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broadcast band is referred to as the 49-m band.ze-w:gmsl.w:/lwy8f n ql j axvz3 .:+ What /lwlqwjw8 ym .nz.se +-g:z:lx:af3 vis the frequency of a 49-m radio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-years ;cxq8lel.jg4,bis/ f4 -. nivf uxyq .away. That is, it takes 4.2 years for the light it emits to reach Earth. How far away is it in met i4yu .lbxiqf-qs/cve8 g.4.f lx ,jn;ers?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distance (not time). How many meters does ligh 4r:jol2u mf/rt trave4uorfj /2m:rll in a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radiocn/) xjss jy :o d86*4rddrfg; waves from Earth to reach Mars
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to scale down Michelson’s light-speed ,7a ytk5n.o:j f 5yzqfsm(1 nbexperiment to a size that will fit in j.zf5,ty5oyk fm snan1b7:q(one room. A six-sided mirror is available, and the stationary mirror can be mounted 12 m from the rotating mirror. If the arrangement is otherwise as shown in (Fig. Below), at what minimum rate must the mirror rotate?    $\times10^6\text{ revolutions/s}$

  Who will hear the voice of a singer firstci07 evz;*twe8p5yg4ux t0 ky — a person in the balcony 50.0 m away from the stage (F xig5*yc4t7tkevy 0 p8uzw0;e ig. Below), or a person 3000 $km$ away at home whose ear is next to the radio? How much sooner? Assume that the microphone is a few centimeters from the singer and the temperature is 20$^{\circ}\,C$.
 ----待选择----away from the stage3000 km away at home  
   s

  Pulsed lasers used in nwpk59-g 8dks1f y z4qscience and medicine produce very short bursts of electromagnetic energy. If the laser light wavelength i9p-y dfqsk 1kw4ng58zs 1062 $nm$ (this corresponds to a Neodymium-YAG laser), and the pulse lasts for 32 picoseconds, how many wavelengths are found within the laser pulse? How short would the pulse need to be to fit only one wavelength?
N =    wavelengths
$\Delta t'$ =    fs

  The $\vec E$ field in an EM wave in free space has a peak of $21.8mV/m.$ What is the average rate at which this wave carries energy across unit area per unit time?    $\times10^{-7}\mathrm{~W/m^2}$

  The magnetic field in a traveling EM wave has an rms streoft7pzf j5l0ru5 .ff. .cglh4ngth of 28.5$nT$. How long does it take to deliver 235 J of energy to $1.00cm^2$ of a wall that it hits perpendicularly?    days

  How much energy is transported across auzd+ce(hx7)kwz: r3o $1.00-cm^2$ area per hour by an EM wave whose E field has an rms strength of $38.6mV/m?$    $\times10^{-6}\mathrm{J/h}$

  A spherically spreading EM wave comes from a 1200-W source. At we b859+jv1it y)i syea distance of 10.0 m, what is the 8biye 1) j i+vy5e9wstaverage intensity, and what is the rms value of the electric field?
S =    W/$m^2$
$E_{rms}$ =    V/m

  A 12.8-$mW$ laser puts out a narrow beam 1.75 mm in diameter. What are the average ($rms$) values of E and B in the beam?
$E_{rms}$    $\times10^3\,\mathrm{V/m}$
$B_{rms}$   $\times10^{-6}\,\mathrm{T}$

  Estimate the average power output of lpzsd7l 9-zz fx r00oz, iy6 g7l;5zehthe Sun, given that about $1350\mathrm{~W/m^2}$ reaches the upper atmosphere of the Earth.    $ \times10^{26}\,\mathrm{W}$

  If the amplitude of the B field of an EM w sag**ewhrv*+ ,fol9i 8.divvave is $2.5\times10^{-7}\mathrm{~Т},$
(a) what is the amplitude of the E field?    V/m
(b) What is the average power per unit area of the EM wave? $\overline{I}$ =    $W/m^2$

  A high-energy pulsed laser emits a 1. )v9f st dhr++y(ik5hj0-ns-long pulse of average power $2.8\times10^{11}\mathrm{~W}.$ The beam is $2.2\times10^{-3}\mathrm{~m}$ in radius. Determine
(a) the energy delivered in each pulse,    J
(b) the rms value of the electric field. $E_{rms}$    $\times10^9\mathrm{V/m}$

  Estimate the radiation pressure due to a 100-W bn zycjt:jp.3s; yve:e xz 745pulb at a distance of 8.0 $cm$ from the center of the bulb. Estimate the force exerted on your fingertip if you place it at this point.
P =    $\times10^{-6}\mathrm{N/m^2}$
F =    $\times10^{-10}\mathrm{N}$

  What is the range of waveleg+nj4.f +,gy0w pg sa /rulk1mngths for
(a) FM radio (88 $MHz$ to 108 $MHz$)    m to    m
(b) AM radio (535 $kHz$ to 1700 $kHz$)?    m to    m

  Estimate the wavelength for 1.9-GHz cell phone receptlf t*k /v;zfw3sw 3cv9ion.    m

  Compare 940 on the AM dial to 94 on the FM diaa42 ,v0u :mdi9mpkqyyaded4 5l. Which has the longer wavelength, and by what factor is it largeraya4vddu2dmq,:e0k5 9iy4 mp?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelenbrxvxmkq sh.+.c 9x 0cip0;+hgths for two TV channels that broadcast at 54.0 MHz (Channel 2) and 806.hi xc x+v;k9+ r0 cx0phbmsq. MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a capacitance of 28*s8;ev(vzkzsb*/ r iy00 $pF$ when the radio is tuned to a station at 550 $kHz$. What must the capacitance be for a station near the other end of the dial, 1610 kHz?    $pF$

  The oscillator of a 96zziapfac l21hj z*t-j 6:inlf8d5 5f3.1-$MHz$ FM station has an inductance of $1.8\mathrm{~}\mu\mathrm{H}.$ What value must the capacitance be?    $pF$

  A certain FM radio tuning circuit has au exz8k(bx c(;0fcs;a fixed capacitor $C=840\mathrm{~pF}.$ Tuning is done by a variable inductance. What range of values must the inductance have to tune stations from 88 $MHz$ to 108 $MHz$?    $nH$ $\leq$ L $\leq$    $nH$

  An amateur radio operanzikh 9 81t(*;xilfm hmkw-) ator wishes to build a receiver that can tune a range from 14.0ml i9n-tzkk;(h8ih mxa)f*w1 $MHz$ to 15.0 $MHz$. A variable capacitor has a minimum capacitance of 82 pF.
(a) What is the required value of the inductance?    $\mu H$
(b) What is the maximum capacitance used on the variable capacitor?    $pF$

  A satellite beams microwave radiation withhpx6in c1.r0 f a power of 10 $kW$ toward the Earth’s surface, 550 $km$ away. When the beam strikes Earth, its circular diameter is about 1500 m. Find the rms electric field strength of the beam.    $V/m$

  A 1.60-m-long FM antenna is oriented parallel to the electric field of an EM wab:r- llz igy/7egbb;aoj */ 1aov.fc0ve. How large must the electric ;a1b ://balf*eo-o7g ci j yvzb .0lrgfield be to produce a 1.00$-mV (rms)$ voltage between the ends of the antenna? What is the rate of energy transport per square meter?
$E_{rms}$ =    $\times10^{-4}\mathrm{V/m}$
S =    $\times10^{-9}\mathrm{V/m^2}$

  If the Sun were to disappear or somehow radically change its e3;o v-, f;mi-9ayvlfs. hwc doutput, how long would it take for us va -;ehsml.fw-;cdo3i,9yv fon Earth to learn about it?    min

  Light is emitted from an ordinary lightbulb filament in wave-train bursts abof:typxdn2p)h1wdyw(la *1f g+0q( l put lln dw)fxy2wytfhd(g pq a1*+(p1 p0:$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it take for a message sent from Earth to reach the fidj4 y,c(hfjyu;1inz 5 rst astron ;5ijj4hzc 1,d nyyuf(auts on the Moon?    s
(b) How long will it take for a message from Earth to reach the first astronauts who arrive on Mars; assume Mars is at its closest approach to Earth $(78\times10^6\mathrm{~km})?$   min

  A radio voice signal 1a:3wv uhkw,a a;s 6dofrom the Apollo crew on the Moon (Fig. Below) was beamed to a: hwav6;13o,ksuad aw listening crowd from a radio speaker. If you were standing 25 m from the loudspeaker, what was the total time lag between when you heard the sound and when the sound left the Moon?    s

  Cosmic microwave background radiation fills all space with an average energylk,u l9t1 y98-fvkosi densk8ys9lkoulv if 1,-9tity of $4\times10^{-14}\,\mathrm{~J/m}^3.$
(a) Find the rms value of the electric field associated with this radiation.    $V/m$
(b) How far from a 10-kW radio transmitter emitting uniformly in all directions would you find a comparable value?    $km$

  What are $E_0$ and $B_0$ 2.00 m from a 95-W light source? Assume the bulb emits radiation of a single frequency uniformly in all directions.
$E_0$ =    V/m
$B_0$ =    $\times10^{-7}\mathrm{T}$

  Estimate the rms electric field in the sunlight tri06n1 h(pzgsoa019 gg yrtp5 hat hits Mars, knowing that the Earth receives abo9grs gp0ih1pnr01 ayg 5 (t6zout $1350\mathrm{~W/m^2}$ and that Mars is 1.52 times farther from the Sun (on average) than is the Earth.    $V/m$

  At a given instant in time, a traveling EM wave is noted to havet e65qw v6;yca its maximum magnetic field pointing west and its maximum electric field pointing south. In which direction is tcyv w6a; 6tq5ehe wave traveling? If the rate of energy flow is $560\mathrm{~W/m^2}$ what are the maximum values for the two fields?
 ----待选择----downwardupward 
$E_0$ =    $V/m$
$B_0$ =    $\times10^{-6}\mathrm{T}$

  Estimate how long an AM anm*. vmho o4jypzc;a3q-u y hr+j(t5w) tenna would have to be if it were
(a) $\frac{1}{2}\lambda$    $m$
(b) $ \frac{1}{4}\lambda$ AM radio is roughly 1 $MHz$ (530 $kHz$ to 1.7 $MHz$).    m

  How large an emf (rms) will be generated in an antenna that consists z+ ks764 /ugu t+rlesi(g hbm9of a 380-loop circular coilz7 k(/lg6b 4+es hmu+9iugs tr of wire 2.2 $cm$ in diameter if the EM wave has a frequency of 810 $kHz$ and is transporting energy at an average rate of $1.0\times10^{-4}\mathrm{~W/m^2}$ at the antenna? [Hint: You can use Eq. 21–5 for a generator, since it could be applied to an observer moving with the coil so that the magnetic field is oscillating with the frequency $f=\omega/2\pi$]    $mV$

  The average intensity of a particular TV st+ 4p -3/apw*:+ogru khx di wtvh/ehm3ation’s signal is $1.0\times10^{-13}\mathrm{~W/m^2}$ when it arrives at a 33-cm-diameter satellite TV antenna.
(a) Calculate the total energy received by the antenna during 6.0 hours of viewing this station’s programs. U =    $\times10^{-10}\mathrm{J}$
(b) What are the amplitudes of the E and B fields of the EM wave?
$E_0$ =    $\times10^{-6}$ $V/m$
$B_0$ =    $\times10^{-14}$ T

  15 km from a radio station’s transmitting antenlv d.nlyi :*+ ,pz0: vpxz)mirna, the amplitude of the electricr :invxy m i+zl.0pv,)dz*:lp field is $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner consists of six plates connected toge7;b2ib9(hc1gav ilil ther placed alternately between six other plates, also connected toge1bi i; cllva(27i9 hgbther (Fig. Below). Each plate is separated from its neighbor by 1.1 $mm$ of air. One set of plates can move so that the area of overlap varies from $1.0cm^2$ to $9.0cm^2$.
(a) Are these capacitors connected in series or in parallel?  ----待选择---- seriesparallel 
(b) Determine the range of capacitance values.    $pF$ $\leq$ C $\leq$    $pF$
(c) What value of inductor is needed if the radio is to tune AM stations from 550 $kHz$ to 1600 $kHz$?    $mH$ $\leq$ C $\leq$    $mH$

  A radio station is allowed to broadcast at an average b 38exfv 8nyy/power not to exceed 25 $kW$. If an electric field amplitude of is considered to be acceptable for receiving the radio transmission, estimate how many kilometers away you might be able to hear this station.    $km$

A point source emits light energy uniformly i-r;i/g u66zsw3 zt cndn all directions at an average rate z- 6g di6nrtzsw; u/3c$P_0$ with a single frequency f. Show that the peak electric field in the wave is given by
$E_0=\sqrt{\frac{\mu_0cP_0}{2\pi r^2}}.$

  Suppose a 50-kW radio station 4qk+n tt1hsoo8-07rjygnl( 3r1ehg f emits EM waves uniformly in all directions.
(a) How much energy per second crosses a $ 1.0-m^2$ area 100 m from the transmitting antenna?    W
(b) What is the rms magnitude of the $\vec E$ field at this point, assuming the station is operating at full power?    $V/m$
(c) What is the voltage induced in a 1.0-m-long vertical car antenna at this distance?    V

  Repeat Problem 65 for a distance of 100 km from,)arbdg6x88kw 8hf qc t:q4+wr3md qk the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level fx,.7k vn p-wzof the radio station of Problem 52 so as to avoid electrical breakdown of air at a distance of 1.0 m from the antenna? Assume the antenna is a point source. Air breaks down in an electric field of about x.z7nkvpw,-f $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$