The electric field in an EM wave tra g1)tho0-w eby s;(rwvveling north oscillates in an east–west plane. Describe the direction)rv-0;hbtows g(1y e w of the magnetic field vector in this wave.

Is sound an electromagnetic wave?o3j 56:le+gkp1x1drdz3xqn vq/ 4ywh If not, what kind of wave is it?

Can EM waves travel through a perfect ynwpio4a 8hq -3w0d:qvacuum? Can sound waves?

When you flip a light switch on, does the light go oj (fd xuig,(scz4qktd 8l/m,6n immediately? Explain.

Are the wavelengths of radio and television signals longer or shorter 4ncw,rki k77 mthan those ncw 7k,4irkm7detectable by the human eye?

When you connect two loudspeakers to the output of a stereoag8w- p-3ayis amplifier, should you be -ws g3ip8- aaysure the lead-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 wouldr 4(l(x7e1bvip ijixd*b k g(* have a wavelength of4 pjl* ki1*(vgei7r i(x (dxbb $10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies acv d/8)fnby49zz.p jns sound waves (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on the same carrier frequency? Exx fe.loe.) cg 3/kn.visiw ad+g4m:4fplain.

If a radio transmitter has a verticrhjo5b r+8ug r 9h4 o twipg+) )2z0qk*ky0tyeal antenna, should a receiver’s antenna (rod type) be vertical or horizontal topzoh) g 0j+yr ytq 8 +5urktw0 4b)9roiheg*k2 obtain best reception?

The carrier frequencies of rcta7j s*5sgb o ;4r:wFM broadcasts are much higher than for AM broadcasts. On the basis of what you learned about diffraction in Chapter 11, explain why AM signals can be detected more readily than FM signals behind low hills 4 r oc s*a:t7srjbgw;5or buildings.

Discuss how cordless telephones make use of EM waves.izl 1tvq ,86rh What about cell phones?

A lost person may signal by flashing a flashlnebt)z3 p -mq1ight on and off using Morse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequency om) n3q -tbez1pf the carrier, approximately?

  At a given instant, a 1.8-A cur5caqed *+l3 v;-lla rorent flows in the wires connected to a parallel-plate capacitor. What is the rate at which tar 3vl+;-ql a*od 5lcehe 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 mag -ls1*,xkk,tqtts r;n nitude 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 p/wv,nqbr ,o;g9g )kn a frequency of 80.0 po qbg)9wkgv/;nn,,r $kHz$ 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 frequenc:qkt yq bas59ize5q8;y 5ul7e0icsy5y of a microwave whose wavelength is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength ofq;u :wpisbk45 a $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequenl(8rgchx38 wr cy $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength of -oin s71dc6v:tp pg27p7aadp 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 from the Sz ys1zqs3t+n /xs52k tun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broadcast band is referred to as/em ksjro/9(s 2d0 jcr the 49-m band. What is ther2srsce/odjj/ 09k (m frequency of a 49-m radio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other le cyk.. i10+7cu xlue2vonx0than the Sun) is 4.2 light-years away. That is, it takes 4.2 yei2elvo+ x 7kx1un0.y. c0ueclars for the light it emits to reach Earth. How far away is it in meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distance (n811t3blm g -wqrt mdyusvmka3/ eo06 ;ot time). How many meters does light travel idk1/em;btumogt yl 8w3s13m v raq-06n a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio waves fromglkohv30vnr1 oudwy 5d+.8e 7 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 experiment to a size )bo hiwyce 2 k++s+ig: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 (F+iig ec h ko)s:++byw2ig. Below), at what minimum rate must the mirror rotate?    $\times10^6\text{ revolutions/s}$

  Who will hear the voice of a singer first — ah-5*hx6 g irce ywc55bru* 2yc person in the balcony 50.0 m away from the stage (Fig5hr5*5c rgc-6 eb 2yxyi*hcu w. 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 p4msfr 4*v )u3ityvd v3vnwm 12b3* qfvery short bursts of electromagnetic energy. If the laser light wavelength is b4*yv3ufrd s)*pi v f4 mvmvw 3q132tn1062 $nm$ (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 *e g,f+dm mnuqj:84yna 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 acsfjd 81 9iz((cj/uayrross 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 st rg8ugk/c1-qource. At a distance of 10.0 m, what is the average intensity, and what is the rmt1- /rug kgq8cs 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 averagex6hwafmpv.qi9h g gh0u;yrvb8 7)w hh* 5xk33 power 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 field of a b.fh+ b8cs70q :moy;ytpz8kawt)q6 nn 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 a 1.0-ns-longsa0/ cc4 a-xyn 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 distance w;(5 w;(b ;ltx(ofnthgdf7y h 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 w j3, pl,8nklquonc) x t*uv7t,avelengths 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-G/cwwna 8 h*gou e7j.f: m2sjh3Hz cell phone reception.    m

  Compare 940 on the AM dial to 94 83bi7pif )5kvq 4ei 4gewx3snon the FM dial. Which has the longer wavelength, and by what factor is it larger? ) np4vgik4 q7f38xbswiee 5 3i
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV channels that broadcast at 54.0 MHzvnd*i /np za;-,)jpn q (Channel 2) aqd pvnp , /nn)z*;ja-ind 806 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a capacxu8mg gx8.nxd 2gpo :v jt /b+7xa .xr,r)9mbaitance 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 96.6r t9h,rewv;j+h ovo (et zu3:1-$MHz$ FM station has an inductance of $1.8\mathrm{~}\mu\mathrm{H}.$ What value must the capacitance be?    $pF$

  A certain FM radio tuninecceg4j* 7y3. s gva0k qe5y6jg 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:m* m ooqs(pv2ov( j+r wishes to build a receiver that can tune a range from +(oprm2ms :*oj(o qvv 14.0 $MHz$ 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 a power of 10i4lbc,z.ds azq3q (z 2 $kW$ 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 pnx l;l8img6d:4 r.ygof an EM wave. How larglp y 8;dig:n4lxgr.6me 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 radically change its output bgsl(.ss+ne4;oxd:y , how long wouldgsxsneyo4 l :(bd;+ s. it take for us on Earth to learn about it?    min

  Light is emitted from an ordinary lightbulbz9)v d 9vrohe/: v2lbk filament in wave-train bursts about 99dhv ve :)/zr2 bolkv$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it take for a message sentiqpsnz9p1hado*m6-o )mw-ft i ox*:8 from Earth to reach the first astronauts on thwsat *z*iip1:mnfopm9 )hqx --oo68 d e 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 oe)/ow)9zqbc) 5/vxbu. aoox 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 la)ozeb)cxq/uawoo x vb)/.9o5g between when you heard the sound and when the sound left the Moon?    s

  Cosmic microwave background radiation fills all space with an averam c+ucx7 i*ygcbk/9d4*qg.ze; khlk -ge energy den-bme;y.i* zdg/uck7q4x+k lc 9g c*h ksity 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)dy+creb7r - frpa0k(+) 85pa kn y bsko1jb3p the sunlight that hits Mars, knowing that the Earth receives abopr enka3y+)- )+a57sc kkyr8(dbpo bj01rbfput $1350\mathrm{~W/m^2}$ 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 t .7vh/xzf qyl6(jt-b ko have its maximum magnetic field pointing west and its maximum electric field pointing soutq6bl/ . -hjtkvf7yxz(h. 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 be if .pwxtel a00 hpw/dc(z(v r:.j 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 ;jc9qb ;nls7vconsists of a 380-loop ci ;vc; 9bsq7ljnrcular 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 parrw xdc/18;qhaticular 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, +*b9gxoq,w igd9)qovru u 9u) the amplitude of the electric fqbu9ud ,)+vogiw) 9 9ouxqgr* ield is $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitancec53) camrmloos +o 23, x7gjac of a radio tuner consists of six plates connected together placed alternately between six othe a53ocs 2,7omamo jc3)c +gxrlr plates, also connected 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 to broadcast at an average power not to excqg40g h17 -g d)vul( gz/fjrfjeed 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 en 6n,.7h* dsy bjsedhp+ergy uniformly in all directions at an average rate sp . s,h jendh+dy*76b$P_0$ 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 uniformw*mppi+m iiu79 84fzd ly 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 u;34h:4p l*vmsd7aneif 7 kxv100 km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio station of Problem 52 so asx s(( dd1n oz/oeq0*hr to avoid electqh /er 0(xn(1zs* ddoorical 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 $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$