The electric field in an EM wave traveling pe iwu 9m6 z2;(x7srnbnorth oscillates in an east–west plane. Describe the directir7(xi29uw mzs ;eb6 npon of the magnetic field vector in this wave.

Is sound an electromagnetic wave? If not, w gk/;dcoammg34q1uv 1hat kind of wave is it?

Can EM waves travel through a perfect i7cagpr l +vspxf+m;* 9*o;6zlkkc3e vacuum? Can sound waves?

When you flip a light 2,pm5g bert(d/5buef tp ,e8 nswitch on, does the light go on immediately? Explain.

Are the wavelengths of radio and television signals longer or shorter th6dd6rbkux+op i:9etyfe yx ,s00 /p4han those hee4k/0 x d+d09p,y66 xtyfopbus ir: detectable by the human eye?

When you connect two loudspeakers to the output of 9gn ee0ry .9* -ejpybar0wx5k a stereo amplifier, should you be sure the lead-in wires are equal in length so that there will not be a time lag by arrbx0 .e-j *095 keywn9pgeetween speakers? Explain.

In the electromagnetic spectrum, what type of EM wave would have a wavelengthqwqv.-h+m+m - ez(ov c of.-ehmw +q-cmvzv +q(o $10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the sx1 jh5y s4bb:eame frequencies as sound waves (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on the same carrier frequency? 7*fg t8yt2 umnExplain.

If a radio transmitter has a yp8hpcy8; j/ 1hph4cgvertical antenna, should a receiver’s antenna (rod type) be vertical or horizontal to obj g8/phh 4 ccyp8yp;1htain best reception?

The carrier frequencies of FM broadcasts are mg(wzjs:(c /qruch higher than for AM broadcasts. On the basisg jw((rsz qc/: of what you learned 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 use of EM waves. --4w t9juy7 tirpn;v/4 b n;c3zxrrzuWhat about cell phones?

A lost person may signal by flashing a flashlight on and ovzi()y*zo sv7 bbx07eg:yn) hff using Morse code. This is xn 7ebyviz o )bgs:7(z)yv*h0 actually 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 current flows in the wires connected to a parallvu*bno0c* r xg)(f a0uel-plate capacitor. What is the rate at which the electric field is changing between the plates if the squabcun r0vx)** og0u( fare 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 peaiv4 7+aozheyl.xnidww )0/h 0s5d ey8k 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 delo*+58vot r and has a frequenceo*lt+o v8dr5y 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 wavelengthrboq p(-+y.2 u-yujrj is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of 15jdlvxe)8wb x: 4ag :clf1hla $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has freque(dfblqx-q.owm2vk )hm:2 0l.qb m g.jncy $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength of 650 ayi l cnzs89p se:b940$nm$. 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 reachfy z57fe6a: hgjcbu wo k);k7qe5. nc3 us from the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio bme :4aspk7rkdz+c ;y 3roadcast band is referred to as the 49-m band. What is the freque sdapk4 +r7:; eyz3cmkncy of a 49-m radio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-years away. That is,m5m/:iu m aqlpv/0 c-i it takes 4.2 years for the light it emit/ iqui c-l5/pa:m0 mvms to reach Earth. How far away is it in meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distance (not ti1g o sq578m.fx z8 b*qqbra2oxme). How many meters does light travel in a yf71g q5x2 8.abxrbs q *moo8zqear?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio jlxl0h1,+lcnu;6co p 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 exp tle6v3r+ uud4eriment to a size that will fit in one room.4l3v6u eturd + 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 rate must the mirror rotate?    $\times10^6\text{ revolutions/s}$

  Who will hear the voice of a singer first — l 0hpvs.01 k; l:tzlvqa person in the balcony 50.0 m away from the stk.lvzl1 sq;lp 00 h:tvage (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 sumkeh :rh:ycyli-o.b16k *-xcience and medicine produce very short bursts of electromak:uc- hyibxk y 1h m:lor-.*e6gnetic energy. If 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 traveling EM wave h*h v9blp6; teoas 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 transporge1gpe m**oyt0kry;j996x cj ted 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 source. At a d;;. pu, gzemnjcsnm w.f: e;:sistance of 10.0 m, what is the average intensity, and what is the rms value of the electric;,;;.f:m. wnn ze m egsuscpj: 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 go4+u . 4/ .jz dkjr(fcj2zlxjoutput 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 ou5l2/j7 eg+3ku s qmodf 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 quago b.d+o)r rt8st 7yl,*.daverage 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 pressu+2t ef m3yom;rg v/z2zre 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 wavetp1h i tn94ke8lengths 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 fort)3 kx5; rabvr 1.9-GHz cell phone reception.    m

  Compare 940 on the AM dial to 94 on the FM dial. Which hrzz 9db bm*qf4-w0bz buy ux s8*61d:nas the longer wavelength, and by what factor iq dzbw04srb:z-6dnmu8zf x9 y *b1b*us it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV channels that broadcast a.:pz1 ;ox)6dza kost nt 54.0 MHz (Channel 2) and 806 Mks:nxzo1.da o6z;p)t Hz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an Ah qwh; c8vr*m32 w6mzhM 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 96.1-us25 6y qa7ctv2q dou;ltu6k4$MHz$ FM station has an inductance of $1.8\mathrm{~}\mu\mathrm{H}.$ What value must the capacitance be?    $pF$

  A certain FM radio tuni v0qf5e.-akr-komhzjji ,e (5fwt,o, ng 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 vcyi. c;uj7p7 p5pi2ea receiver that can tune a range from 14.07 u7e5 ii;cvypcjp.p2 $MHz$ 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 microwaethx))dm/6a f8zi x* gve radiation 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 ca lle5sn1)n37(udr o electric field of an EM wave. How largdnr7sc3o(5) a l lenu1e 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 nct a6z-onessyhy2o* d6; -u ) n0kt/houtput, how long wo; -o2/ hsu aston zn)6-cnt06 *ydeyhkuld it take for us on Earth to learn about it?    min

  Light is emitted from an ordinary lightbulb filament i*pcyvg2qc)p pm 3pts b658my8 n wave-train bursts about cp)y8q8 2vtg 6*p3m 5 cpsbypm$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it take for a message wgml(alik.k.0g(vp9 sent from Earth to reach the first astronauts on thevlkpmg k0(9 (a.l. igw 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 n kt21vduh7zh a:5sq5ca1r a2the Apollo crew on the Moon (Fig. Below) was beamed to a listening crowd from a radio speaker. If yv n ucq5tasz2h5d71ak2h ra :1ou 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 averagea x0e25 x stagq52a.fd energy density 52sxagfqdte.5x2 aa 0of $4\times10^{-14}\,\mathrm{~J/m}^3.$
(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 sunligcr;)qpy p182j5yq, pueg,4afhu7l q p ht that hits Mars, knowing that the Earth receives about q4hl7rau;pj)g 1yce 5fpq,u82, q ypp$1350\mathrm{~W/m^2}$ 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 dzpi sb+a t2l425 j+mb8,ktskto have its maximum magnetic fie b pl jt4+82 zk2s+msbdk,t5iald pointing west and its maximum electric 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 bd rkvo ,8xdggcleh:4p*i/f ;3e 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 tha0q faki +juju22vt y/;t consists of a 380-loop circular coilaf v jui2 2q0/jtk;yu+ 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 stcx :1ozt hgj/.xwxm1sm*jr . b) (bm*jation’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;t z nd14w4; gyz eb vib8n)b8jtn*7fr, the amplitude of the electric fie wvt4bi j;7*zb1f genbdy4tzr n8)8 ;nld is $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner consists of six plates con9( quhhdu or,eikh,7 (n((js onected together placed alternately between six oth7hsiuh d9(oj,uqn rk(e,h(o( er 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 al6 0;upkb zrw(dlowed to broadcast 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 uniformly1*-yn3zagx3iufyylu0 vc / -s in all directions at an average rate g-y nu*0aus f/v- lz3i1cyx3y$P_0$ 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 directionsj +v2,etve,z1 .: wle; lgkh* 3zsxyxa.
(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 fo rdgl ntl zk.0,v4kc78:t(jtbr a distance of 100 km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio u g g2--sexa1y(fhg i9station of Problem 52 so as to avoid electrical breakdown of air at safg -x 1ig-egyh(92 ua 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.]    $\times10^{11}\mathrm{W}$