The electric field in an EM wave traveling north oscillates p (1mo;mcn (okin an east–west plane. Describe the direction of the opo1m n(km(; cmagnetic field vector in this wave.

Is sound an electromagnetic wave? If not, wh/gtqa( yyr (i1gr+i e;at kind of wave is it?

Can EM waves travel through a perfaf9jcyg2vta ;eb v952ect vacuum? Can sound waves?

When you flip a light .jj* jq 0(qosakho idu/ct3t6ec5;. sswitch on, does the light go on immediately? Explain.

Are the wavelengths of radio and television signals longer or shorter+81v1xlyckorgc8 v3u i p /bl. than those detectabl li188 rbkgc1 olxyp3cuv /v.+e by the human eye?

When you connect two.s8rcx3bj fu0 loudspeakers to the output of a stereo amplifier, should you be sure the lead-in wires are equal in l r c0sxf8bj.3uength so that there will not be a time lag between speakers? Explain.

In the electromagnetic spectrum, what type of EM wave would have o)qhb3 49va-dahi 7oc a wavelength of h4avb7o )d q- hic39oa$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound waveqk4x 3khz a5-ey e0q*7v1vw czs (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on the same carrier frequencywgpw+n6 b v 9 *7/fuoq5 apk)pnxtc02r? Explain.

If a radio transmitter has a vertical antenna mhzriq2g 8l5,, should a receiver’s antenna (rod type) be vertical or horizonlzgr 8iq,5m2 htal to obtain best reception?

The carrier frequencies of FM broadcasts are much higher than for jjbxp 9tu,(,k AM broadcasts. On the basis of what you leaupbkj xj,t,9(rned about 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 ure5 he40wrdf+ghzn :1;4 sns-r5z htase of EM waves. What about cell phones?

A lost person may signal bmo n or26:sk+yy flashing a flashlight on and off using Morse code. This is actually a modulated EM wave. Is it AM or FM? n2 +y6ookmrs:What is the frequency of the carrier, approximately?

  At a given instant, a 1.8-A current flows in the wires connep9*bjm0q;n8t-c dir s cted to a parallel-plate capacitor. What is the rate at which the electric field is changing between the plrs9dc it0mqb -8j*pn ;ates 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 d )2e*xs opfd: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 ga9:)ca75y :k3)ajr;tsim1x nintp h and has a frequency of 80.0a15 tn:khja9m ipx7ys: t) 3g;cn)iar $kHz$ 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 wavelehurji sc74cm .-zc 4y.ngth is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelengn(qqgf 3adij/ut4c2 t: te32 f6x9 lwfth of a $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequencyultlp6/ pfskk39j+6 k $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelen0b0vz6jl/i 8rvtw z4 qgth 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 l* a3ao/0 bcwvwight 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 the 4eyu u*-d4opiz0w:kt +9qwx (s 5djf fxp)/ou.9-m band. What is the frequency of a 49-m radio signauup 0 p 9+t(:dq4/zjo y) .xos-ekf xiw5fd*wul?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Swlac9je/dsas0 i: *l7un) is 4.2 light-years away. That is, it takes 4.2 years for the light it emits to reach Earth. How far away is it in m a*:0s/cwla7 d iejl9seters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of disz b/m29yjb 8istance (not time). How many meters does light travel i2/8zyjsbbm9 in a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio waves fsljm*uj (8x17u/l zvxjm0 ,k arom 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 tb5rx.pk6tsuo dmg1o 2c)g8c j,mcic2 5 5gu5uo 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 iguxcg.cc5j s2m 8rmg)tb i5 1 dpck5o6uuo2,5s 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 singer firs i+ pn7,0cbijtoo0(o5,zwy hw t — a person in the balcony 50.0 m away from the stage (Fig. Below), or a person(w7o, +0 jbo it05cwihoyz ,np 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 sci4 msmkuhe* n2mg9nx ,gev72/nence and medicine produce very short bursts of electromagnetic energy. If the laser e2729 m*v ,egs ukgnxh4n/nmm 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 ti*p9qae77rxppxiwhk/g4 n p t4p h m2 fb5l-5.raveling 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 (3 x1r0 fw h:enxe5ur(dks.a oacross 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 spreadinmgy-v 8u5n8rq g EM wave comes from a 1200-W source. At a distance of 10.0 m, what vqgyr8mn - 5u8is 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, gam:kzg (-xvj 1iven 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 wave iq-:tn zx49fd bs $2.5\times10^{-7}\mathrm{~Т},$
(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 tby.n(1-u1fexot ym1v mdu.lp937of.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 ,x/hdr .6sza. x,tqee pressure due to a 100-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 wxw ls54d2w3/ zlfh z.q,cj:s
(a) FM radio (88 $MHz$ to 108 $MHz$)    m to    m
(b) AM radio (535 $kHz$ to 1700 $kHz$)?    m to    m

  Estimate the wavelenge+nd -w y+i-h 5radcf m7x+6huth for 1.9-GHz cell phone reception.    m

  Compare 940 on the AM dial to 94 on the FM dial. Which hd c;te zz.) ltgxscr1*,gw-dzds5;7las the longer wavelength, and by what fld; dz.xlcts , )egt dw7g;z15 -rczs*actor is it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV channels that broadcast at 54.09fvg r 7zwf vtf1 ,2iwo6d0o/l MHz (Channel wf9o7 z, 2vr6gwoi0d vl/f1tf 2) and 806 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the* a.c 6j3hezum tuner of an AM radio 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 va2uc7kt0 t9e96.1-$MHz$ FM station has an inductance of $1.8\mathrm{~}\mu\mathrm{H}.$ What value must the capacitance be?    $pF$

  A certain FM radio tuning circuit has a fixeaf cs/jo d- ofl50kyw(fs 02te**7jpyd 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 thatl5bhd/gj x-: r 4m-vsy can tune a range from gy5d b-:xmhlj s-/4rv14.0 $MHz$ 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 powerl9 r iotnf2- ;lj1ze:i 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 parallezq:w fom -7( dmocr1s0l to the electric field of an EM wave. Hom(-rof0 sqz oc md:17ww 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 s:mfve+k2qiu f+ n5j-or somehow radically change its output, how long would it take for us on Earths 5efvk nfiq2mj:- u++ to learn about it?    min

  Light is emitted from an ordinary lightbq(0lga 4+/r pfy0ibnp (v5wka2.io jy ulb filament in wave-train bursts about lw (nyk0y aq/ r24.i0pv (fijap+5gb o$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it ta 4.hc1 cmmkf8eke for a message sent from Earth to reach the first astronauts on the Mo 48 cmkc1.fhemon?    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 (Fig. Below) was beki1ln k)5s l:vamed 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 5il kvln)s:k 1the sound and when the sound left the Moon?    s

  Cosmic microwave background radiation fills-fts w33hlyhh)/s-cc all space with an average energy densityh/whc tsc-l3hsf3- )y 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 sunlw (q:a4z-bffe/by z s)ight that hits Mars, knowing that the Earth receives aboe-as)bw:fq ( fzb/y4 zut $1350\mathrm{~W/m^2}$ 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 have5u klt5u) vr1c its maximum magnetic field pointing west and its maximum electric field poivlurk1uc )5t5 nting 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 AM antenna would have to be1;f7lk *orgw m 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 anteno :dagxu86 s4.bvta(:jpyj:c na that consists of a 380-loop circular cus8:.ydjcvxb4at j6 : (o:pagoil 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 signal is ywzo our1s2c, (91ksnch7* vu$1.0\times10^{-13}\mathrm{~W/m^2}$ 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 ampli)yer / (pzh, v4mmh(jctude of the electric fiel 4(j,h c zm)(ve/mryhpd is $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner consis usu4 ax oocq(q pb391go;;9jets of six plates connected together placed alternately between six other plates, also connected together (Fig. Below). Each plate is9c3gxq4s;;jb o9pae1 o oq(u u 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 /lf,9ia )usgfi +u0zkat 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 an average rateko: arw2p0q d..zi zf4 z.pq4fz k0:.ro w2i ad$P_0$ 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 qk),wx(-se jnw69bb a 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 km from t*p b uc8pbo2y ;,)t.nmu8nkf ehe station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio station of Problem 52 so as to a5f7 dt2jnwiwm1x 7 j*ivoid electrical breakdown of air at a distance of 1.0 m from the antenna? Assume the antenna is a point source. Air breakstjwii7 5w2 7fx *jnm1d down in an electric field of about $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$