The electric field in /sg)vspco.su zfs 7jt.ww 51.an EM wave traveling north oscillates in an east–west plane. Describe the direction of th zwj5 )uss.7.sw.ptc v/ 1sogfe magnetic field vector in this wave.

Is sound an electromagnetic wave? If not, what kingsm mapgk4p0g8 /w; s)d of wave is it?

Can EM waves travel through a perfect vacuu9m*devr .knn8q-4e ,nebzl1 dv-t*f rm? Can sound waves?

When you flip a light switch db 6unn7 j ui/bvcg vyz,,0v)6on, does the light go on immediately? Explain.

Are the wavelengths of radio and television signals longer or shorte,*ea43jcv5wuk m o oq0kr17x qr than those detk q7 o5vu4mxc1qoe* wj,kra03ectable by the human eye?

When you connect two loudspeakers to the output of a stereo ampl)d 18wf s9: hk8)xe4mq fsbrbbifier, should you be sure the lead-in wires are equal in length so that there will not be a time lag between speakers? Ex ) dsh91xb8: s8kbf4f)mq bwerplain.

In the electromagnetic spectrum, what type of EM wave would have a xj6-r 6asb;gdwavelength of s6bj-g x;ar6d$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound waves (bu 37,-vlcr :x2 tiqkd20 Hz–20,000 Hz)?

Can two radio or TV station3f va3r,y uqjk)e:l+ es broadcast on the same carrier frequency? Explain.

If a radio transmittx x9 t:hwl4z(2u j2fqper has a vertical antenna, should a receiver’s antenna (rod type) b24j:ht zlqx(u9xw 2f pe vertical or horizontal to obtain best reception?

The carrier frequencies of FM broadcasts are much h*l0ja :l)q.xxtwl + /czzudsoq7b96nigher 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 oj9a +x:bdl/zlczu *w 7lt.)q q xsn0o6r buildings.

Discuss how cordless telephones make use of EM waves. What ab3 5kg0nhs7wzm9c e,xn .i:rul65w qms out cell phones?

A lost person may signal by flas 8jr + mz(/dn..gnqqdshing a flashlight on and off using Morse code. This is actually a modulated EM wave. Is it AM or FM? n/q (s8gnrjz..m+ddqWhat is the frequency of the carrier, approximately?

  At a given instant, a 1.8-A current flows wg uxg9/ -4rpain the wires connected to a parallel-plate capacitor. What is the rate at which the electric field is changing between the plates if the square plates are 1xg4 rg9u /aw-p.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 magnh0e.o6shb -kt6xf e3hitude 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 w7+6 hxard4et0wbr e 8a frequency +w e trdbe07a6wrh48x 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 wavelk)h/q*4, o cppbkcvi .ength is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of jvlk-3. ,oux ++byruw a $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequtsyp1hps/0w i)ol-z 2ency $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength of 65msvncal+0d-c .2vb,zb js2 . s0 $nm$. What is its frequency, and how would we classify it?    $ \times10^{14}\mathrm{Hz}$  ----待选择----visibleinvisible 

  How long does it tak 5b4 z7.i0nazk)s govpx)nv l*e light 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 zm 43vyk45qo beh-nj6the 49-m band. What is the frequency of a 49-m ra6 5nbqmk44o z-vy3jeh dio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-years away. That is, it takezi-b+1ehfi o)w mn 3p g*5sz+ys 4.2 y+s- oz *ii m+3nbf)gwzp15yhe ears 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 /:xjkxnw2t. 5poau n3 distance (not time). How many meters does light travel n3 pojk5w:t. 2 naxux/in a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as rvv)3;.zzg 9 fgih2dw9pij sy7adio 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 light-speed experimentc3*uqcv 76zfgt; idm ; 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 rot;v7fdzqc ;m3*tciu 6g ating mirror. If the 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 singer first — a person in the balcony 50.i;n3e )ite- mym i3w48bj,jp z0 m away from the stage (mi b4;y- ,e3nzimi j8p)ewt3j Fig. 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 very short burstbaj*)z yl w55ps of electromagnetic energy. If the laser light wavelength ibz55 )awyl*jps 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 rgbm9wm 9)ik.fms 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 across a b: ur op-wue99$1.00-cm^2$ 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 g ,ijx:b9+nhhe 2/q n f7y0ibi1200-W source. At a distance of 10.0 m, what is the average intensity, and what is the rms valfn2hq xg0bey:b, /iih+in9 j7 ue 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 poweryfa fcez:(b5d3rdk 72 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 obhx7 gcdqm23v-*w)on3vea, cf 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 laser emits a 1.0-ns-long pulse of average poweboc7dgo;6h +q r $2.8\times10^{11}\mathrm{~W}.$ 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 /ne g5 zx84yyndistance 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 waveleng.v1 /k)gy xmrxths 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-GHz cell phonn9d4/kspksdhx fh)38 e reception.    m

  Compare 940 on the AM dial to 94 on the Ficg)b 3-. wlong+ a8axM dial. Which has the longer wavelength, and by what fact-b aggci.)+a8 onxl3w or is it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV channels that broadca 167 w 3bfx:aii djyt(ha+cpo3st at 54.0 MHz (Channel 2) aa jc6wh t7:pfayx1i(i o+d3b 3nd 806 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of antxv3djjv : e1- 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 cvmiums/0) f196.1-$MHz$ FM station has an inductance of $1.8\mathrm{~}\mu\mathrm{H}.$ What value must the capacitance be?    $pF$

  A certain FM radio tuning ompqjg+3 ;n s;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 receiver ig1 /o:kqif7bthat can tune a range from 14.0gi ib/1q:k 7fo $MHz$ 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 : domk gwy.3r.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 elect vr5j0-qrcq 8;tmpve4 ye3b/sric field of an EM wave. How large must the electric field b t;vsecvyr-j08 pbeq m /r3q45e 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, how lonlkgzr (il .l z7s:, cxt(clu*)+d/sjng would it take for us on Earth to u +crikstz*7/gx.llnj, (c l ):z(sdllearn about it?    min

  Light is emitted from a ys)ctg jybp- 6qdrce2gakj :c5 6*us(p(v0 d;n ordinary lightbulb filament in wave-train bursts about qg2)c*j5rb ck6(-pgcd0 a pyy;udvs:e( j6st$10^{-8}\mathrm{~s}$ 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 reacmgzo7 8h uyzxgm;+h6 bdh -1,sh the first astronauts o xu+1o -b6hgg;hd8,s7m zm zhyn 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 jazxtj55ork .0e+s g5 the Moon (Fig. Below) was beamed to a listening crowd from a radio speaker. If you were standing 25 m from the loudspeaker05xozse5rag +kj. 5t j, 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 wet:sfo:o nse6 2m :-jwith an average energy densis -:we nm 6so:tef2:ojty 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 Maru oq, rd3:qu7fs, knowing that the Earto7r u3f,d:qqu h receives 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 txu0tb-tzarm 91 +kvkc(t-u8 rraveling EM wave is noted to have its maximum magnetic field pointing west and its maximum electric field pointing south. In which direction is the wave traveling? If the rate of erc-xr bz+9ut1 uk 8t( ktm-va0nergy 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 i:+s2c-a w lvomt 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 antengu.x00 xwd h+lusd66fna that consists of a 380-loop circular coil of wiref0.lx0 d 6gxd h6su+wu 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 intensitzsvm bj8 7 jjj1js(g.(w3yq(ly of a particular 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 stat /rcdo4(i ez*p6lvjm; ion’s transmitting antenna, the amplitude of the electriciodm /*( ezp cjr4lv6; field is $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance u51eie. : d0ywd2 eesyof a radio tuner consists of six plates connected together placed alternately between six other plates, also connected together (Fig. Belod i50e 1.yds2u:eeyew w). 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 f cn ezr.z7wua8).2iuexceed 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 exn 4-jc 0e8ctlight energy uniformly in all directions at an average ratejcc 08txn- 4ee $P_0$ 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 di x w53(us/uyab(g8 exdrections.
(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 d wp8e6d srs+vq 11do:ksr)7n eistance of 100 km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power l16,qro)0ej c7myv8jtwlo(c y evel of the radio station of Problem 52 so as to avoid electrical breakdown of air at a distance of 1.0 m fr6or0 jloy )t7q ,yvwjcc1( 8emom 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.]    $\times10^{11}\mathrm{W}$