The electric field in an EM wave4nu*e/dtvro - traveling north oscillates in an east–west plane. Describe the direction of the magnetic field vector in this wave. *tdvu 4one/-r

Is sound an electromagnetic wave? If not, what kind of wave is iwz-b,o ,vygf9y5tc i:t?

Can EM waves travel through a perfect vacuum? Can sbdul05 d* vszizh,+; lound waves?

When you flip a light switch on, does the light go on immy)ykerhhs. * ct;x/n l)js 83uediately? Explain.

Are the wavelengths of radio and television signals longer or shorter than d3bhyxxksp4t e: 2l-k2r;m 5gthose detectable by the humank 5p;:sxdt2xye hgb24km 3l-r eye?

When you connect two loudspeakers to thel:ho3h)cn:p 4l *kvzc output of a stereo amplifier, should you be sure the leavlk c4lhnz*o: 3p:c h)d-in wires are equal in length so that there will not be a time lag between speakers? Explain.

In the electromagnetic spectrum, what type of EM wave would have a wavelength( wjw :6oiu:j- uqezn9 of 6un-qw:e iuz9j: ( wjo$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same f r.r.s 4gjpg:urequencies as sound waves (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on e +l1 usahcm*/the same carrier frequency? Explain.

If a radio transmitter has a vertical antenna, should a receiver’s acu8p34tj. q( eyrsuhn5*8gtg ntenna (rod type) be verticaj *t q8. uhnecgtpu8(gyr345sl or horizontal to obtain best reception?

The carrier frequencies of FM broadcasts are much higher than for AM broadcasts.qr 7 6ivqc)0 6smnf2ti On the basis of what you learned about diffraction in Ch i m)vt2q60r7q ifsn6capter 11, explain why AM signals can be detected more readily than FM signals behind low hills or buildings.

Discuss how cordless telephones make useug7.yiom0) 9ybto1k6n 2gmme of EM waves. What about cell phones?

A lost person may signal by flasfgj/*6s1) bcr-lb d6c m3j.sjjz*pp hhing a flashlight on and off using Morse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequency of the carriejbj16c sj*6s fc. ld)pg*zb-r phmj 3/r, approximately?

  At a given instant, a 1.8-A current flows in the wirero*ek*f5 ,sxj lh9:ct.1n ysxs connected to a parallel-plate capacito5 :ex ,.rcflys*xk* oh1ns9tjr. What is the rate 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 magnifydoz7+y:s9b: 29pdn1 q l jkztude 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 ver imgwzg;u((jb1n(yk +tically and has a frequen 1bjm;zyw+n g((gk i(ucy 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 is f9:61 xwex bydko6nnz 1kt8hia 3c(v81.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of a rg lf 8187c5dbxyj3 mr8dxqd *$29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequencypm:w bu jwc: +0ra0v.y $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavb 7l,,pwbv r3selength 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 fro5uo scmg9 8e.am the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broadcast band mb-,vtivzte ) hf 1d:*hs1qk4 dxut53is referred to as the 49-m band. )mzfds, h13:qt5-tbk14h*x u tdveivWhat is the frequency of a 49-m radio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) isyb1p kdq+8 0v (ivlp)y 4.2 light-years away. That is, it takes 4.2 years for the ligh 1 p(lv+)yiy08qpk bdvt it emits to reach Earth. How far away is it in meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distance (not time). How man )63la,n8 b0xtxd uilwy meters does light travel il lina3x6x8b) 0uw t,dn a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a0 6te wr yq960ne3txmd message sent as radio 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 lmuh-vs 68d- s0 ad*qxxin6xl6 pk+/csight-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 arrangel6qcaixx0n kv8 6pd*6sx/s +-ud-hms ment 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 zodfpa :(r ygqe.2-e,za07ra qwxc+8of a singer first — a person in the balcony 50.0 m away from the stage (Fig.-.r e8aq(d7yx g,w orpqzaec f: 0a+z2 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 medi7 q0bz,knoei;cine produce very short bursts of electromagnetic energy. If the laser oei0nq 7;bz k,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 hay.8o,/ eh5jaua: rycs(76c6qk pv ea 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 transported a2u +mrcm xf tt/+l5.kscross 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 ;5 b6n4 qyu.ywm;q5bxztj0 ija distance of 10.0 m, what is thejxbybi;t yq .65;45jnqwmuz 0 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 power output of the Sun dk0mh60;e/jt asm xi,, 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 w7iq 3ksu*q zustlb6a1jdt73;ave 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 1.0-ns-long pulse 5 fqdi4czx,77gr h/md 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 1hbm y7a *fc n)tut80r100-W bulb 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 wavelengths for w)hw o5 ylh;2n: i5-zzyhmvspyctni3)k;3 :n
(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 pkv+ p8+hk0yjs gj 6w2lhone reception.    m

  Compare 940 on the AM dial to 94 on the FM dial. Which cr3ftd;oi zxh ao1i3y35.kk3has the longer wavelength, and by wchdkai ixy3 5t3.z3fr3;1o ok hat factor is it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV c07b x 4 , td;/fwbf,dic:ebxvuhannels that broadcast at 54.0 MHz (Channel 2) and 806 MH 4b0:7xe bx,u ,tdfdb;w/ ifvcz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a capacitance of 2800 uu( )svry3gt*$pF$ 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 9m k:+oaqt3o:y +rcy,xfrk ,f(yo m2v -6.1-$MHz$ FM station has an inductance of $1.8\mathrm{~}\mu\mathrm{H}.$ What value must the capacitance be?    $pF$

  A certain FM radio tuning4 zr dioyiu1+d*l e.x6 circuit has 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 receive.yc,u-i koq)x r that can tune a range from 14.0 x-qi)ck,oy . u$MHz$ 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 a powecd n 18q ;v0flb2y2fgxnfy/g 9r 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 para f :giz,odeqy9 )r*w2 svy.zk3llel to the electric field of an EM wave. Hywsik2 9)* gd3:zq,fovz.ey row large must the 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 disappear or somehow(sl i e5:rgjt8 radically change its output, how long would it take for us o(tgs:lj 85erin Earth to learn about it?    min

  Light is emitted from an ordina(bd(4wn 82dv p2 c-rt8 iynfcwry lightbulb filament in wave-train bursts about n2 88fr2itpn4 wd-dbc(yw( v c$10^{-8}\mathrm{~s}$ 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 astr 2d6ma 9r4faffm r hanh(-q)y,onauts on therrh9ffdy-2f6mq( a hana4 , m) 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 fv7qya fmmq)1;rom the Apollo crew on the Moon (Fig. Below) was beamed to a listening crowd from a radio speaker. If you were standing 25va 7q )ym;1qfm 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 alf cje a*fu7/ e2jm61ubl space with an average energy denf*fu mec1 b2/ua j67ejsity 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 hits Mars, knowur ;4t3z-s2 ogsy fyj,/d26x2pzo s d6rgl6vwing that the Earth rezd-uspr6 g66r 2f w3 ,;oyo2 2dsz/tlg yjxs4vceives 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 have its maxhpd2ugfap9z h6 3)6 woimum magnetic field pointing west and its maximu2d9fpwgahpz 366 u)oh m 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 Aesr1;zrlk7iemn0t+p ;1 .t ax 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 gene:x,o2t+am. l2 a xtrfq 5p2jefrated in an antenna that consists of a 380-loop c,:ref xmt2p 2l+ xoaf5.jt2qaircular 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 particun /h2. :fmx.vakj r4kjlar 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 transmittingck2ewvzn/6 1j j.c gc1 antenna, the amplitude of the electric field is1w e/cg j2.61zcvc nkj $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner conjzszdty) 0c-9sists of six plates connected together placed alternately between six other plates, also connected togeztd0 ycsj9 )z-ther (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 power not to exceez4l5s;dj *myh fz48 ff9 o-t4c*qkyxs d 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 an5e:(z-xgbnn 2f1nz nb)hs u l5 average ratenns15uz-l 5bg(nh:e2fxb )nz $P_0$ 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 statiys/ afy yf63f dpjb w9jhv)l1s,r2g/;on 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 die9ybl; cjc76tstance of 100 km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio station of Problem q55c m/imebnn+ z, kszk)mk(; 52 so as to avoid electrical breakdown of air at a distance of 1.0 m from the antenna? Assume the antenna is a5cqi(mn ,m / znmzk s;b5+k)ek point source. Air breaks down in an electric field of about $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$