The electric field inp6fnpnq+x7 lgooy:(58 4gi ptj3xu 4e an EM wave traveling north oscillates in an east–west plane. Describe the 8 36gf+74nxioq 4 lpje: ugn 5yoxptp(direction of the magnetic field vector in this wave.

Is sound an electromagnetic wa0 (t9;2xuq;fm kwpbnxve? If not, what kind of wave is it?

Can EM waves travel through a perfect va-w0qkt+-nt jy+eskr(z ymw-.cuum? Can sound waves?

When you flip a light switch on, does the light go on iqi ih q4b08s ;gl2*t8ju4vahp mmediately? Explain.

Are the wavelengths of radio and television signals longer or sho6tvcd z7kn3ahaeee8e;0w d50iv ybj 1 y. *3iqrter than those detectadk0ay ie*d50bct3v wzqev1 n6ie 3j7 y8.eah;ble by the human eye?

When you connect two loudspeakers to the output of a oe76q qu) 8smustereo amplifier, should you be sure the lead-in wires are equal in length so that there will not be auqes) 6q7 8omu time lag between speakers? Explain.

In the electromagnetic spectrum, what type of EM wav5x(rlf0z -zb jku4 2eqjy+f/se would have a wavelength of -kzbxlf0jy42u( jq/sfe +5rz$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound waves (20 w) l3pq6tvfvwwsj3i9 l0- xi ue3k*+vHz–20,000 Hz)?

Can two radio or TV statklw(qq8c/ u8nx ,e.n( ubdwp9ions broadcast on the same carrier frequency? Explain.

If a radio transmitter has a vertical antenna, should a receiver’f kpby)dyrdc-20 zh,/ho( 0zas antenna (rod type) be vertical or horizontal to obtain best rerc,dzh0o)bdhk yy2/ a -p(f0 zception?

The carrier frequencies of FM broadcasts are much higher than for AM broadcasts.oa+; .uie2yt+ bmji ,1(fd szz On the basis of what you learned about diffraction in Ch +t,ez;mjbfid2ozysi(1 a.u +apter 11, explain why AM signals can be detected more readily than FM signals behind low hills or buildings.

Discuss how cordless telephones make use of EM waves. Whatdc1i;qjyy1 a(*d46 n t3cwhsz about cell phones?

A lost person may signal by flashing a flashlight on and off *9swm(ge 5o ;tccj qryr+w;)fusing Morse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequency of the carri;w9r eoc +sqyj);fc5 tm (*grwer, approximately?

  At a given instant, a 1.8-A current flows in the.hh(2pjq3 ter5bq d* l wires connected to a parallel-plate capacitor. What is the rate at which the electric field is changing between theldhj5(hb 2*eqp qr.3t 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 9 x3z vcp-b7l.2 jqcotin a traveling EM wave has a 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 vertical7 bn04nxq .+ era5xea:vr 7qftd. ph8oly and has a frequency of bp:ao5e 70xr.+ r.e4atxvhq dfqn8 n780.0 $kHz$ 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 wavelengtu8xnuf33+ qb6s87eww ts(ze zh is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of a nsaqf*a7jer e1-iu6/ $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequencyrrdv/o,o:sb(e 4 zc)x $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength of 65v:*gr.hmx2 c2 xfgrt60 $nm$. What is its frequency, and how would we classify it?    $ \times10^{14}\mathrm{Hz}$  ----待选择----visibleinvisible 

  How long does it take light t qi h6*e;n q*iy)jbnwe*l o4kdp:/x-ro reach us from the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broadcast bfrh n bqm7.5zm nn)6p0and is referred to as the 49-m band. What is the f. 7n5p0mrh fnm 6qb)nzrequency of a 49-m radio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-years away. That is, it tk -d -f):ubvnkakes 4.2 years for the light it emits to reach Earth. How far away is it in met- v:f -)kuknbders?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distance (not time). How many meters ds /wd46yx6im5.(er8sg23ey xy ch fuc oes light trax32y r/6 gs5yewxm.h fes64 (ycid8ucvel in a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio waves fromrqlc( ;0kbn,zn8 (lpc Earth to reach Mars
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to scale down f7 bw5/ 9uk*t vl+xpidcq 1h9gMichelson’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. Below), at what minimum rate must the mirror rotate? cxv*qt9h 1l 9kp7dbu/g5 ifw +   $\times10^6\text{ revolutions/s}$

  Who will hear the voice of a singer f7s7l7mqa mi 5bfunou:( o,c0first — a person in the balcony 50.0 m away from the stage 7:au, (07bin5oqcumlf m fs7o (Fig. 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 ve1e )m j:6gq :-ts8ih+er+8u gjdswmylry short bursts of electromagnetic energy. If thwsd e m:mg6g irqh+s1-y+ :jjeu8l)8 te laser light wavelength 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 in a traveling EM wave has an rms strength of 28/g7 1.q r dns5ykh*yis.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 transportedivzht4r / +a x 97eig,rz+9xjt 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 spreading EM wave comes from a 1200-W source. At a distw)7nau-na2 nm 5j3a nvance of 10.0 m,3 m 52an)vuw7 nnnaja- what is the average 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 powerk6q : 2f2cf9t5wlj gz +cetyeu.0* jrk output of the 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 fizu . 53fb9cow s:1 qzwz1t.ejh, xszefm)ul.; eld of an EM 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 laser emits aj e:7 z25whjqa-g)ofsu1g . fg 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 olue* kai1ue,y c/n:2at 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 wavelengths for k:py.rc rslk1c 7lz q(-md7*a
(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 receptionxnjf*, -)grs e.    m

  Compare 940 on the AM dial to 94 on thervs .zu5h j8;qvkbs 9p3in/ hsu4s3 0y FM dial. Which has the longer wavelength, and by what factor is it larger?uus jnpsz;.0v i345 syvb8 /3khqrhs9
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two blvf0 ulg-1v*TV channels that broadcast at 54.0 MHz (Channel 2) and 806 MHz (Channel 69v -bgvul10*f l)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a :ocushkz4l2h m5tc /jb; pr17capacitance of 2800 $pF$ 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- vg*vbvc0;zs4 3uz)pd $MHz$ 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 a fixevm l09ocqrfn- c4b 8r)d 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 tweh 8wss3vd, 5h0 +knwishes to build a receiver that can tune a range from 5dswtw, ns3 h0 e+kvh814.0 $MHz$ 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 micr*hml zsgq6o-,7 +z ajzowave radiation with 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 +f k:8j 72keaha t4v6ir)c bbfto the electric field of an EM wave. How large must the electric ftc jeb+8 6 4a fkbk2ir7fa)h:vield 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 output, how lonizjeh kf-2(b st8 4jcbs i5p7.g would it take fo bt57bzjfe ii4hks8( s2.cpj-r us on Earth to learn about it?    min

  Light is emitted from an ordinary lightbulb filament in wave-unou /v)lwm 73train bursts about mw)ul/v 7uon3$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it take for a mep f7nh28l+-to a475k,wdxchw kuooe6ssage sent from Earth to reach the first astronauth e, 7w 65+pnwca4kth7ku of-o 8xlod2s 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 from the Apolln8-f4hrdtp/4g;svz ec fjvd4 ei , ( qivrx,--o crew on the Moon (Fig. Below) was beamed to a 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 Mooq4it8hrd - 4/fcvgiz 4(rv,x -es,-ne;vf pjd n?    s

  Cosmic microwave background rafn2s 8h5gpp 1y3hzi6+t r; m/8a puaqodiation fills all space with an average energy density o538appmzs628 /hi nua; tfg r h1p+qyof $4\times10^{-14}\,\mathrm{~J/m}^3.$
(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 hits Mars, knowing that th,)-gh.h;s+w vjok 9 ge7 hcpwwe Ea-;oe gpch7hvh w,w.+skwg9) jrth receives 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 Ek0txei- yr y+f1cc/t) M wave is noted to have its maximum magnetic field pointing west and its maximum electric field pointing south. In which direction is the wave travc /)k xyyte+-c1i0trfeling? 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 be if it were .u1zi,e- q::bnc omle
(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 conf62 xz/grrz 8ysists of a 380-loop circular coil of wire 2g /z86xfrzyr2.2 $cm$ 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 station’s sioi) mnx-5:stt(e+ gasgnal 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 amplitude of the evo d xkwr6,,u;lectric fiv odwx6ku,r;, eld is $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitany 7(w0q*il hvg)es6otl/ )ue dce of a radio tuner consists of six plates connected together placed alternately between six other plates, also connected together (Fig. Below). Eacehew(ql sli)gy 06u*7t/dov )h 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 po:+stw q5k1x jnwer 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 in all directions at an aver70ja1*uk;i1 dj58whg qw urd xage rate jq17;dgwhu *rw5 8u1x jd0kai$P_0$ 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 emk6sz984 2bf1h3rirde ,zvh imits 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- m8qu du olh/9.ck u8f1l:zrx km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio styj5/ 2kv-t6j 3oddab96fcz yvgmc t +*ation 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 abom/6dgvj+jd 2-t95fy6b*co3vk a tyzcut $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$