The electric field in an EM wave traveling north oscillates inh2ihgfi, u*- :.on1ap kp0,ia)rgvop an east–west plane. Describe the direction of the magnetic field vector in this avgo -h :*i 0ag,p2iu)pfrpk1.ho,niwave.

Is sound an electromagnetic wavlllgfg4k7iu37g5gs + e? If not, what kind of wave is it?

Can EM waves travel through a per8he ejf t(w3 nn)6lyi3fect vacuum? Can sound waves?

When you flip a light switch on, does the light go l hww:-ot+bf0( se,xlon immediately? Explain.

Are the wavelengths of radio and television signalsk) /b,uhm) tg0;,d5mlexmmmac zto + 5 longer or shorter than those detectableec0mghaxtmb;5,/ utdkmz m,+lo 5m) ) by the human eye?

When you connect two loudspeakers to the output of a stereo 4m- ,;cfadjgygu 0yj ,amplifier, should you be sure the lead-in wires are equal in length so-0,g4 y ,fjdujm ycga; that there will not be a time lag between speakers? Explain.

In the electromagnetic spectrum, what type of uwd2.dj8c dd 5EM wave would have a wavelength ofdud5.2 8w dcjd $10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as soundsx 41 3( hb bgjb3qdcoft+nn88 va1h,i waves (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast onzzulx0zbqbvhv0 00 (9 the same carrier frequency? Explain.

If a radio transmitter has a vertical antrsa8 mc g:jmn)tccvv61 z57y7enna, should a receiver’s antenna (rod type) be vertical or horizontal to obtain8vjcm )s:n76 ta1g 5c7mczr yv best reception?

The carrier frequencies of FM broadcasts are much higher than for q lkw :,hqvcf) wmhu), op..7dAM broadcasts. On the basis of whal.w)wqd o, vcu7kqp .m:,)fhht you learned about diffraction in Chapter 11, explain why AM signals can be detected more readily than FM signals behind low hills or buildings.

Discuss how cordless telephones make kp76,z gg dmwnl(p dyk1xj+6w;g/i9p use of EM waves. What about cell phones?

A lost person may signal by flashing a flashlight on and off using Morse code.mx sh-u. (w:xtkd* g6i This is actually a modulated EM wave. Is it AM or FM? What is the frequency of the carrier,*:dx h-si.k(gw xtmu6 approximately?

  At a given instant, a 1.8-A current flows in the wires connec u q/6 7veo0d1frb;chcxgb;d 4ted to a parallel-plate capacitor. What is the ra 6h01rfc7xdb ;gued ;oq 4/bvcte at which the electric field is changing 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 a peak magnitude jr8g0+ (dex 8 ulxvg5fx63h rz7l6lgdof 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 oscillatesbx/ ( k*mci2h 3gy1im2jrit i4 vertically and has a frequenc/i(42xt1iib m3rj 2*m kyighcy of 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 wavelength ibtpqe3*- t cl .y1jssc4:qib;s 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of 53ch0vmbk)qs qnl 5g/:x-ufza $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequency8glpu +5znux/ $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength5-:;l gf fc*d;fuyh5es6z chq 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 wzwagd7*7 -zn to reach us from the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave 8ork.d)6m7zeb8j sxh” radio broadcast band is referred to as the 49-m band. What is the frequency of a 49-m radio signahmj7 rskz8e)d.bx86o l?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-years r)bblgy-b0)p7p ; hla5ytk d3 away. That is, it takes 4.2 years for the light it emits to reach Earth. How far away is it in lpb r)pb t7d)aylhb0-y 35g;k meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distance (not time).o/7iu s5u7pjcsk my5- How many meters does light travem u /s k75-iso7j5puycl in a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio waves from: x* s.psf;yjm Earth to reach Mars
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to scale downc/.itn3yq)ixyq (kx* ghb+1a Michelson’s light-speed experiment to a size that will fit in 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) cbaiq1.*n xky+/3x iyh (qtg. Below), at what minimum rate must the mirror rotate?    $\times10^6\text{ revolutions/s}$

  Who will hear the voice of a singer first — a person in tgq+6 mget,c 8ohe balcony 50.0 m away from the stage (Fig +c,qgt6 o8gem. 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 science and medicine produce very short bursts of u+auy7a fyaf :459bdqa:w/iz electromagnetic energy. If the laser light wavelengtfu+5y a/: 9fi4:7aqd az abyuwh is 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 inbr p6g nx;e/zb26f;vr a traveling EM wave has an rms strength 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 transporte/4dvrq ep i8+7 xedqt5d across a $1.00-cm^2$ 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 spread9 wy4af 2dmu1ling EM wave comes from a 1200-W source. At a distance of 10.0 m, what is the average intens9my 42ulwfd a1ity, 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 thedisvh c9i:hk+x*s * 9w 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 .acfyo2 gpb, hk;nx/, wave 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 lasevb84 yi,uip 0rr emits a 1.0-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 bulb at a(4r6i( urdzvju*hv.h,s4c o k 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 wavelengths f3*cmu w * i1oitnpt1 3,d+m:0erdzcapor
(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 reception. ng /7j+umbnl3j0 z7vn   m

  Compare 940 on the AM dial to 94 on the FM dial u;9.qx1 o9 *)oodfbzbva1.6ona mhii. Which has the longer wavelength, and by wz1f 19oabab9 iu*;6o.n)im . x qvdoohhat factor is it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengt4 z5sw7t4da ; vvwn do0,/xnc6szk+hfhs for two TV channels that broadcast at 54.0 MHz (Channel vvswf,h 7d zxnnws 4c5 4ok/; dz+ta602) and 806 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a capacitance of 2800 yy ;:mjei. mv9log**e$pF$ 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 96.1-7u2jvh6a526xs.cfa.+ yaumejj: v v a$MHz$ 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 0z,k1gq6rwmke(cbi u*3h1 rb0etm)zhas 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 operator wishes to build a receiver thay b0(0 ,ked3la pwdrej4 lw*e8t can tune a range from 14.0 (38bl* rdy l0d,0eaj4e kwpew$MHz$ 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 wit db0a3fm; sw7 ed*l+ulh 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 o+fulcd/,i buh;l3/-fxa r(e lfa 6n1pl4sou3 riented parallel to the electric field of an EM wave. How large must thf/l euf1+63 xd-onr; l(aa p3,ifbh/c 4lus ule electric field 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 dib2 dn7xyxswx2 r+2 6qesappear or somehow radically change its output, how long would it takeqwxx sexd627 +n2y2r b for us on Earth to learn about it?    min

  Light is emitted from an ordin*tnof) 0w3.smeu wh*nary lightbulb filament in wave-train bursts about to3shm*f*wnu)e0 wn .$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it tn+8 ilfmp8v ikm-yz(0ake for a message sent from Earth to reach the first astronauts on the Mof 08-(+k nzmyipim 8vlon?    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 from the Apollo crew on the Moofyerxi6. f4xj+6vc3 xqh y /gld26pb-n (Fig. Below) was beamed to r6bp/2x. if hcq g6v3j+ 64exdy ly-xfa 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 4xl 9fk36cpcd space with an average energy densityl6cd9 pfxkc43 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 that hioy6yxaa5dc+4.z 9 jjg6 iupy7ts Mars, knowing that the Earth receive7jy a9 oc 5p i6aydzgj6x+y.4us about $1350\mathrm{~W/m^2}$ 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 havesrs3l9nyrp9 0 its maximum magnetic field pointing west and itsrn9psr y 930ls maximum electric field pointing south. In which direction is the 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 antenna would have to bm0 nb;lyn8.qly gcimn4,yt 3+e 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) wil .r .i9ccp(qpal be generated in an antenna that consists of a 380-loop circular coil of wireaqpicrc .9.( p 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 intensityk4 gb p6upn-d8 of a particular TV station’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 antenna, the amv,qq g wkv(j1*plitude of the electric field is1v kqqwvgj *,( $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner consists of six plates connected tttq*, b zn.-z/ 6pkafjogether placed alternately between six other plates, also connected together (Fig. Below). Each plate is separated from its neighbor by 1.16tj ,-q. nza bfpkzt*/ $mm$ 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 powgw8.)w0kdr1-o rsudlx6 uqnq bk612per 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)jqmgu8. ikr+( in+l ;vlxq3 e energy uniformly in all directions at an average rate lk (r;u m+nq8lg+i xi) 3.vejq$P_0$ 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 emits EM w-.pz a2 xbzra(hqbqi,i++ss2aves 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 :z 0s aev+bb.zfrom the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio statig ph+ogqh m6 xb18p6 f74)bgzron 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 brehp6xmb8+ 1qg 7fg64)pb rzoh gaks down in an electric field of about $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$