The electric field in an EM wave traveling north oscillates in an east–west p xy sznfqkaon6v43op/6n(: t-lane. Describe the direction of the magnetick y6 n4zva/so(qnx t-npof:63 field vector in this wave.

Is sound an electromagnetic wave? If not, what kind of wxnwgs()p)dwl8yk q ) 9ave is it?

Can EM waves travel through a perfect vacuum? Cat 7*nhgo5lrj wtt.(q; /d* fmgn sound waves?

When you flip a light switch on, does t 0 t u;0jcvg j7smxpkb+7y*0ekhe light go on immediately? Explain.

Are the wavelengths of radio yq: lc oh4p)1wand television signals longer or shorter than those detectable by thepc: 4howlqy )1 human eye?

When you connect two loudspeakernk(-t c w-fq:ps to the output of a stereo amplifier, should you be sure the lead-in wires are equal in length so thak-c-p tqf:wn( t there will not be a time lag between speakers? Explain.

In the electromagnetic spectrum,g jv5e8nene63 ,y,dc 0 brtob6 what type of EM wave would have a wavelength of 0 5 ey83b bcee,o g6trvdn,j6n$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same fy -lf06h27zf 0yt6m y;dr9 tsl)ocd h0pyxy w5requencies as sound waves (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on the same carrier frequency?xvl mgjx9f()/ Explain.

If a radio transmitter has a vertical antenna, should a receiver’s hr- v3d,8kee eantenna (rod typere ,de e3hvk-8) be vertical or horizontal to obtain best reception?

The carrier frequencies of FM broadcasts are much highezlcpp )pbng *a, 7.tw/z lhbm6ztx26 ;r than for AM broadcasts. On the basis of what you learned ap;g. t6b2 zzwn/7m zbhc,pptx all 6*)bout 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 u j,8; ilfrour,ko;d9 ise of EM waves. What about cell phones?

A lost person may signal by flashing a flashlight l:g:q7prg ( z /tfz8q s:cg9jnon and off using Morse code. This is actually a modulated EM wave. Is it AM or FM? What is the fr/f (q: jst:97 pgnzlc 8gz:rqgequency of the carrier, approximately?

  At a given instant, a 1.8-A current flows in the wires connected to a o-4gjoca1.- yk+b jv ,ife lg0parallel-plate capacitor. What is the r0,. yf1jaoe-- +4kg jiboglvcate 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+e c 9p c-r*qs;ujdbc, 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 vertically and has a f8xf(b xjk +7erb+tf kg ;wm)z0requency ofk+r+m(xj0e)bzk; wg 8tf bf7x 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 ./6geyne(8zq ;ujdcvwavelength is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the waveleng2 td ufa9p. 1pn*c*tppth of a $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequencygtuol77 t4ew w0 n6y*e4*ryny $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength of c4.;iuf.tx ce 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 li6i 0dn8sbqv/flnbv k19 sk 4c(ght to reach us from the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broadcast band is referred to as p rhm82z em (;zee ik6:w.ybd e/3zd7nthe 49-m band. What is the p wmbee8:.m / 32nz;7e6zde dkrz(hyifrequency 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, ityqk 0b76d(5rjt,pufyq 2z-za takes 4.2 years for the light it emits to reach Earth. How far away65bq0 z(2z7d,r-fpy qauy jkt is it in meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distan n0 1tfxbl-cg9ce (not time). How many meters does light travel in a 0b9n-gfxclt1 year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio waves from Earth to reach M0 ;)n0ef tl9ul xrr4cears
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to scale down Michelson’s light-speed ezv f77qh451-lcfnz6u pz-h tuxperiment 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 thq cup6tl71zh 4 n v-zffhu5-z7e 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 sinzp-icj yaj: ,.lb:p2 iger first — a person in the balcony 50.0 m away from the stage (Fig. Below), or a person 3000 l,b-pjapizi :j2y:c .$km$ 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 ioq 01me:2a3 nnx2 p0uib/g 2 fatqrb8bursts of electromagnetic energy. If the laser light wqbaxao3p 0/ut1 i :n2f8 em 2qbrgi2n0avelength 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 5h7c.sf dhnu6rms 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 transpori780 smjc(yobted 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 dis w6fm; +dk 0kj0o5flcstance of 10.0 m, what is the average intensity, and what is the rms value of the electfd0k 56kmloc wf0 j+s;ric 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 outpyqf 96vjaowqsm; ;3)out 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 field ofi 0- ozd4yd8hy4 j,rw(yi7iea 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 lasem *rkwz8ei6igq +v*c-r 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 dista3l+j.fi4i y wje3mfu:nce 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 xemuq-j/d+u-kauv. 2j5ipo(
(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 :b: ej-/u2bm cpv)caxp d0y8l,do+gmfor 1.9-GHz cell phone reception.    m

  Compare 940 on the AM dial to 94 on the FM dial. Which has thel3kr ynqke7 :yq20m1-;2,xten ioxes longer wavelength,e3q2 yqey: esmx;o7irk n-nx 0tk2 ,1l and by what factor is it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two Tl)n-s0jhk3swk e g(8 vV channels that broadcast at 54.0 MHz (Channel 2) jks 3eshg-( 0k)8nlv wand 806 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM dfu7req s60p2 ,k2 doqradio has a capacitance 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.jvf2z6 ilw7,w1-$MHz$ 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 fixe8b1o ge9 tsk.sn9 cuv)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 wishes to build a receiver th*tai ivpgwb808he-)nat can tune a range from 14.v8wi* i0e ahgtnpb-8)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 microwave radiation with jnbt w.:r)h7oa 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 ele vtbm+6:: qpbpctric field of an EM wave. How large must the electric fie:p btbp:+qv6 mld 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 disau5,:x k o,.hewifw( jlppear or somehow radically change its output, how long would it take for us onef jh xi5:wl.ou,k( w, Earth to learn about it?    min

  Light is emitted from an ordinary lightbulb,c j0hq60h2( ;hylvtahvao p 7 filament in wave-train bursts about v; hqt,(0oal y27ha6v0hjhcp$10^{-8}\mathrm{~s}$ 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 first astrod b6gzi gdo5** q;p*pmna;d*q*z6*o5ip md ggbputs 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 Apollo crew on the Moon (Fn;mhlh0 -uwp8 m*w8mxig. 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 the8- pm0ww;xhu*8lmmnh sound left the Moon?    s

  Cosmic microwave background radiation fills all space with 6vdwkuu19 xx bm0r 5b.an average energy densit9b5x.0 d 6 k1uuxrwbmvy 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 electr vb/a mh5wcx6wnj 3.j2ic field in the sunlight that hits Mars, knowing that the Earth receh6xbww2/ . mjc3na jv5ives 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 EMxml;1 bj0hs j2m6vs8bv 0a/gu wave is noted to have its maximum magnetic field pointing west and its maximum electric fielx8jmh vg0v/s1jm;2bbal 0us6d 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 A /zugsc xei+,zmu(i /+M antenna 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 generatedu4e dp)pcazyiearu ;u9za 04xw2+,2z in an antenna that consists of a 380-loop circy z)aza 4xpcuz+i0w2d4u2 u9 rpae,e;ular coil 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 station’-e l5.lb 6ctg* fbnf8vs 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 trr8tnd 83zoa a9ansmitting antenna, the amplitude of the electric field ianz8dr 9o38a ts $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance oujl g kyz-7xzf4:cw0 .f a radio tuner consists of six plates connected together placed alternately between six other plates, also conn7j 0g.kcz yf4 -zxwl:uected together (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 mk4ncm5, 7kz x7zdr) bto broadcast at an average 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 lu.hs*8d49twzk u;j ma ight energy uniformly in all directions at an average rate um*h.d89j;4 tazks wu $P_0$ 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 waves h2 uuk k4 kt-(borcf /zt(yn8b/ip,(xuniformly 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 the statio((cre9n qzb4s5sb 3t hmms.j6n.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio station of Problem 52 so as to *s; ; u psw:nfmm9bup.i; 0fvpavoid electrical breakdown of air at a distance of 1.0 ufp:pm0ip f;m; s*.;9 vwbsnum from the antenna? Assume the antenna is a point source. Air breaks down in an electric field of about $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$