The electric field in an EM wave traveling nors a z7ck6x ,e3f rs8xagk7m5f2th oscillates in an east–west plane. Describe the d6zm8sfx ,7acfk3sg75arekx 2irection of the magnetic field vector in this wave.

Is sound an electromagnetic wave? If not, what kind of wave is yj( s46(4q)vbbcpe0 vd 8tss rit?

Can EM waves travel through a perfect vacuum0efgb05i s, b11bwqfw +jw s/m? Can sound waves?

When you flip a light switch on, does the light go on immediately? Ex r(-.mbx;vcpm,xh9 ioplain.

Are the wavelengths of rry- ldkoju)(tb9 y(y.adio and television signals longer or shorter than those detectablek)oy( tlrb9 dyu(y-.j by the human eye?

When you connect two loudspeakers to the output of a stereo amplifier,g+wz arfk/da8d*p5 7r should you be sure the lead-in wires are equal in length so that there will not be rrdgw/ pfd+aza*57 k8 a time lag between speakers? Explain.

In the electromagnetic spectrum, what type of EM wave would have a wavijsc0uug ,- z8elength of su0 ,iz uj-gc8$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the samzre (n- o.3d7i 3al33nl aincc5w-smt e frequencies as sound waves (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on /:3 rggcnqy)9zuj nl* the same carrier frequency? Explain.

If a radio transmittef2tn csg/f*f2;( ockhr has a vertical antenna, should a receiver’s antenna (rod type) be vertical or horiz/sgn(fc ;fftk o2h c*2ontal to obtain best reception?

The carrier frequencies of FM broadcasts are much high;r9p**zpiz/ we y3j i,vv b3xeer 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 o j;bpeer*yv9i33 /zpw *vzi x,r buildings.

Discuss how cordless telephones make use of EM waves. Wh7/ra)mdc(t() j;j g ek8hmw urat about cell phones?

A lost person may signal by flashing a flashlight on and off usingw,i2u92 97vn pcv hwye Morse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequency of thew99upw,h2ney2v v7ic carrier, approximately?

  At a given instant, a 1.8-A current flows in the wires connected tf;79 ixzqw ;efh-2uqqo a parallel-plate capacitor. What is the rate at which thzqh;uqif-x2 eq7f9 ;we 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 t*b oeh9ql9x0qraveling 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 oscv8gla4 o 2jhb*,qyla+ r2j 4qoillates vertically and has a frequency of 80.0 2bvhlljq qg484,+2* j a yrooa$kHz$ 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 waveua+ qedk 3y+.qgl7n4lc5ycj k2 p7gy5length is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of a alj7wo+e,,nvn,qg, q$29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequengiz wid *w j48i*i4l1qcy $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength of 650 m.cqbe, uhjer78btt n +62zb( $nm$. What is its frequency, and how would we classify it?    $ \times10^{14}\mathrm{Hz}$  ----待选择----visibleinvisible 

  How long does it take lightseomvdux0ccnh d): h-h 4h(z a87r,j + 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 49- 7qy9xztv)u-x8;ra/t2cn pg s m band. What is the frequency of a 49-m radio gc2xz )r7/y usxvatnpq-89; tsignal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-years af43z5 rs j+): qgctblytxw2(kway. That is, it takes 4.2 years for the litq ftk4y+ 3(swbz: l5xcj2)grght 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 many meters does li57l.brqen, , lj9krgzght travel inrl7 be nz5kjlq.9,g, r a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as rawbxgy:8 x vr,48 chn6adio 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 experiment to 9+yfk zarz:)lehxioag/+f+7g:0 lsy a size that will fit in one room. A six-sided mirror yli: 97+hysgza ezlf+)rx/f0aok:+g 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 rate must the mirror rotate?    $\times10^6\text{ revolutions/s}$

  Who will hear the voice of a singer first — a person in the balcony 50.0s1 +r:ttk47y ktlg.;sap5jh c m away from the stage clkg + .sktha:y;t54p 1j str7(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 v2xund2px /ps 0ery short bursts of electromagnetic energy. Ix2/xpsn2 p ud0f the laser 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 trafb(+ppi bi d ;:x(j7lwu7pid9veling 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 transpo2xelxm.e clpb*b 6 y.8rted 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 sor9ie -xiu4:-r6 6 tsck,;byxfuecn (nurce. At a distance of 10.0 m, what is the average intensity, and what is the rms value of thfi-c;-cu xb(n u st6 yxre4rk:n,6ie9e 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 2hv7cymshro x+llh9 ;3syw 96 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 .q (hxf)og1;;hhfxekof 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 u,.lo 5q wi-)zkoivnn+i7nblo.j ) ;spower $2.8\times10^{11}\mathrm{~W}.$ 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 of 8.0gam:sbml rw iw.)z/30 $cm$ 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 wave),bsavnx k/spp5e6j s;;q(xd lengths 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 c*u)8y(lobzt adbw9 r (6 1yb 6-dmmctoell phone reception.    m

  Compare 940 on the AM dial to 94 on the FM dial. Which has the0uq1xf5o wewo, (fe5 v longer wavelength, andvfu5q,o( e51w 0oxwe f by what factor is it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV channels that brov-tu pa7kt0;cns 0 ua /) pkhi:hxm:+kadcast at 54.0 MHz (Channel 2) aush; :+x icka: kk)huntm0pt/ - 7p0vand 806 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM k9)rl xoq y7/ 4gyph ng1nlbsq2tr8;/ 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 1h.qn rf;m*x ti6bpz+fbt0c :96.1-$MHz$ FM station has an inductance of $1.8\mathrm{~}\mu\mathrm{H}.$ What value must the capacitance be?    $pF$

  A certain FM radio tuni o0jq ;6o40qj 9jzjuqw2fw2q png 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 )w57u/fjy x-m9d gvsf a receiver that can tune a range from 1f5f m y9g uws-x/v)7jd4.0 $MHz$ 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 rad6h)gdd8zxxh ki02;7tt j2 g cniation 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 fiexs jly*9vrut16p-iq 8jf- :celd of an EM wave. Ho*s-9v p rjej1q-tx8ylcfui: 6w 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 radically change apd5 :,qw; j ogedmj9d4f-7 zkits output, how long would it take for us on Earth to learn abofe795m dj;wgq-d ,ajzp d: 4kout it?    min

  Light is emitted from an ordinary lightbulb filament in wave-train bursts abondie; 5j2wb+ yut enbi25y+d jw;$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it take for a message sent from Earth3 j l97 qek0gj.mpnyc9 to reach the first astronauts on the Moon?q lnm9 9jpc0k3g. y7ej    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 z 0j,*ererbw7a7 v2 icApollo crew on the Moon (Fig. Below) was beamed to a listeninbe07r a ezwrcjv2*,i7g crowd from a radio speaker. If you were 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 avo+7oscem47k serage energy densito7ekms 4 so7c+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 electriqogm p .-ohb:8c field in the sunlight that hits Mars, knowing that the Earth receives aboutg pq:.boo-h m8 $1350\mathrm{~W/m^2}$ 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 maximumrh6du vsfr:d56t 9mt c 87;mcu magnetic field pointing west and its maximum ecdu 7mhcstf r:9um 5d86; trv6lectric 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 AM antenna would have to *m:gmj z ,toq(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 antenna that conu9yyy.m 93 s vv*8piwrsists of a 380-loop circular coil of wirw.s8 3u9yyviym r9pv*e 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 9in;s -wp1/lk*makzqj59 hxv 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, the amplitude ofc jf;u+8/abkf the electric jc au b;/f8+kffield is $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitanhauc .k;. *lcnce of a radio tuner consists of six plates connected together placed alternately between six other plates, a;h. * nul.kacclso 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 exceedaj 2p)g y:,n:o4zgpg:imbpd zc yg6)u)d+c.k 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 al-an 1sn )8boukn./+v ewe4(l vb l0jstl directions at an average rate eu1tew.(v/sj ob4b0+nk s-a)8nlnvl$P_0$ 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 wavs4 0m2.047kkrk e(mvcbvmpfw es 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 thzso d vy2; w9(9a,zugke station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level ofsb1fn,wt*x x fp,t/ +xk,l.yb the radio station of Problem 52 so as to avoid electrical breakdown of air at fby*/ tx xnwsl1.bk+p ,,x,tfa 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.]    $\times10^{11}\mathrm{W}$