The electric field in auh l 9tez8fmxgi0 0 x3*h7ikk+n EM wave traveling north oscillates in an east–west plane. Descr k fi+z0l g9*h 3x08mhuktie7xibe the direction of the magnetic field vector in this wave.

Is sound an electromagnetic w)ijskxpuy 2:-bkx0f. a36 hmzave? If not, what kind of wave is it?

Can EM waves travel through a perfect vacuum? Can sound q)3gf hs6 zs7(s qap qem1de:(waves?

When you flip a light switch8embofw 0/wcu )2-7hugee* u a on, does the light go on immediately? Explain.

Are the wavelengths of radt/ gwxtup6:5ofb e9hs3x8*cy io and television signals longer or shorter than those detectable by t5gxt p86*: x s/tucbywfo e9h3he human eye?

When you connect two loudspeakers to the output of a sto j5ki5*ocjb, ;zl0ozereo amplifier, should you be sure the lead-in wi 0oj z cokb5i,l5;o*jzres are equal in length so that there will not be a time lag between speakers? Explain.

In the electromagnetic spectrum, what type of wg5 nf ko096x-aas .q anyz8m;EM wave would have a wavelength of m0o 9 g8kyz;6n5-qxsafn.aaw $10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound wavhliez93mk.r1f )- w wses (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on the same car ovh(9 x./ z6:hnbpdbvrier frequency? Explain.

If a radio transmitter has a vertical antenna, shoz8fx,s c2t9px aavi0 :uld a receiver’s antenna (rod type) be vertical or horizontal to obtain beszs a axf:9 t2,8vxci0pt reception?

The carrier frequencies of FM bdry1:fcr1cm- lm +;6ykbk1+vrf-ky- knrdn2roadcasts are much higher than for AM broadcasts. On the basis of what you learned about diffraction in Chapter 11, explain wh--l++dmr2bdv-n nf ccr:y r ky km1;1 6kk1fryy AM signals can be detected more readily than FM signals behind low hills or buildings.

Discuss how cordless telp1+ j/xe,qvqr ys-9taephones make use of EM waves. What about cell phones?

A lost person may signal by flashing a flakk gm9edaikq71/;n2;j zc vx ar15 1odshlight on and off using Morse code. This is actuaajk1 a25kdc/dzio1r vmeknq1g; 9;x7lly a modulated EM wave. Is it AM or FM? What is the frequency of the carrier, approximately?

  At a given instant, a 1.8-A curh o 8k cbrepplbhrk/*7v+5+*prent flows in the wires connected to a parallel-plate capacitor. What is the rate at which the electric field is changing between the plate +kphb+h ke7lp*pvrc*/br 5o8s 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 travahesm)p70wabvcu)ms ) )* sz* eling 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 oscifwuvb ;oq(x mf/+;p 4illates vertically and has a frequency o4q m b(xupvofiw;/+f; f 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 microwf;pie1nxj: 3v ave whose wavelength is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of aou8v.h ub6ywd l;1va 4 $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequenvra;ptuf4s 1( awz-q 2cy $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelenq 7 3/wp4h3 fkybrt;prgth 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 from the q7ou kp sap* ym l;m8q: +orl89gtc.3tSun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” raut1e z e svy b7p/qj7a6h/.3tfdio broadcast band is referred to as the 49-m band. What is the frequency of a 49-m rabe67euzs /jp/. v 7yhf3t1qat dio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than t7dncjpa kxc/ e 3k06y)he Sun) is 4.2 light-years away. That is, it takes 4.2 years for the light it emits to reach Ec3a ykd)j p/ce60 7xnkarth. How far away is it in meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distance (not time7 jxo 9z8gbw6,or righ1-/dyk). How many meters does light trahr oi 6xjgrkwgybz , d/87o-91vel in a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio waves from Earth to r2m z1 r4tdrl-9xwk g0q(a- gogeach Mars
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to scale down Mitmtkh)crbc v0s2k 1em l7nyo9937 ga(chelson’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 r c y(3179t bkoh)9aemr0mvnct7sg2 lkate must the mirror rotate?    $\times10^6\text{ revolutions/s}$

  Who will hear the voice of a singer first — a person in the balcony 50.0 m l(pqr owt4qs-:u1iq.away from the stage (F4: (p. srw-uoqiqltq1 ig. 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 pr*:f 7uxp;zfhi cj1r6 aoduce very short bursts of electromagnetic energy. If the laser light wavelength :;f61fihp7cau* rz jx 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 e0rou3ks( 7tj y -pxd728.5$nT$. 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 tranwoe:,;uz va :n /jd-vo*pt k9esported 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 soz3 x d) optji/c h3q1n42 rdxr9h6sig6urce. At a distance of 10.0 jd34h2hz)1ipxndsx36t/6orqc9 r gim, 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 power output of the Sun, given that apj g e:z(+k8sgbout $1350\mathrm{~W/m^2}$ reaches the upper atmosphere of the Earth.    $ \times10^{26}\,\mathrm{W}$

  If the amplitude of the B field of an EM wave is ;by gx 1+rgrw7$2.5\times10^{-7}\mathrm{~Т},$
(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 bpd46w2vo1l eumq 6-nnr s; (pof 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 b2voh;g a :z-lu2ucvj7gyh.r2 ulb 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 fo ,axvy93,ojw/ dyjual4gf f94r
(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 recep zqmkgz (:)aq8tion.    m

  Compare 940 on the AM dial to6/ns5quowg +pzq,hk d k a+/p( 94 on the FM dial. Which has the longer wavelength, and by what factor is it l6qqp,( s5dhpoang/ zk+ +k/uwarger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV ckmmz/u * 5w vwktj)v+ 7yb.-nxhannels that broadcast at 54.0 MHz (Channel 2) and 806 MHz /t+wk* )zvvub7x.5jn mywkm - (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a3oir;4do qg ,q- fe6wv 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 96.1--lt/;h. 9rg vkmn*q7 kwvul 1*qrq-qp$MHz$ 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 fixedwjhw7;6 :e(ft/;glae/;qu 1j tpyu zo 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 that c:9yp0ms z)lhcan tune a range from 14lm p cs:hz)90y.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 gu7r(q hxe+asg,/p0qradiation 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 to the electric field owylzgr;y vut46k 98y0f an EM wave. How large must the electric field be to produce a 1.0y60t 4lk9ywu; rgyv z80$-mV (rms)$ 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 somehoan p y+u48e2piqt) lz*w radically change its output, how long would it take for4l) uz* i+2nyeq pap8t us on Earth to learn about it?    min

  Light is emitted from an ordinary lightbuleb,u7bq l x)5qb filament in wave-train bursts about )ql5e7xq b,ub$10^{-8}\mathrm{~s}$ 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 rcs l7:afbpe3 *r-j 7wheach the first astronauts on the Ms 7-l*rp3cj bwfeha 7:oon?    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 tb1 m94tl 8fdxyhe Moon (Fig. Below) was beamed to a listening crowd from a radio speaker. If you 814tfy9bmlx dwere 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 space with an average energy dtu/zx7j72 x3dcp) emaenszt u3de2 xcj pa7mx7)/ity 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 elec7y s16oje(smdtric field in the sunlight that hits Mars, knowing that the Earth ss 7y( md16ejoreceives 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 w5 -tk(wk,c p;n.h. 1ldmprtwu c;*hsvave is noted to have its maximum magnetic field pointing west and its maximum electric field pointing south. In which d km wcs hnk .w dl.c-5hvtt,(rup;;*1pirection 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 ans x/,i92qmi/+nj 7 2jy ymellntenna 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 generated in an ay w( q(daf*u0pntenna that consists of a 380-loop circular co *dy0uq(pfw (ail 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’s signa+9b q yz)wad2eb g21kkl 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 t(e;uu xo1jtv+ransmitting antenna, the amplitude of the electric field isv (xu;tj +uo1e $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner consists of njqh w,ec+3*l six plates connected together placed alternately between six other plates, also connected together (Fig. Below). Each plate is j*lnw,c+ he3q 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 brozi)+fxcb8 z(r adcast 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 light energy uniformly in all directions at ak ej b86lve+7mn average rate je6ek8v+ bml7 $P_0$ 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 uniformly in all rp(bv68m m v+awcc(5y/. uimjdirections.
(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 diec;i j e7 ogqrjh+39k;stance of 100 km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio mp(yscqbw.t2k7j-l8 + j i1vt station of Problem 52 so as to avoid electrical breakdown of air at a distance of 1.0 m from the antenna? Assume the antenna 1jittvl(my+8j 2pwqk b. cs- 7is a point source. Air breaks down in an electric field of about $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$