The electric field in an EM wave traveling north oscillateb.1 p+lrxri0dpm a30ykf3 zv8et 3nt2s in an east–west plane. Describe the direction of the magnetic fi0f r8pmbkazyliv2 3tpr.nxe+0t31d 3eld vector in this wave.

Is sound an electromagnetic wave? If not, what kind of wavt(v4,3;jqveb)ao 6 n o jn8diae is it?

Can EM waves travel through a perfect z8;).veaujdv * bhl 6w 5ewyf0(q og4uvacuum? Can sound waves?

When you flip a light switch on, does thewhd1yb mjpwniauy- vd/(: j5 25 8)fbj light go on immediately? Explain.

Are the wavelengths of radio and television signals longer or short x3m4x1jc(hkwhnvo 1zlsl:)*ck r e8 *er than those w1l:k*ek 1mrlv hxhszc*xj n 4)8o3 (cdetectable by the human eye?

When you connect two loudspeakers to the output of a stereo amplifier, shouldx *-iix *nm2qw you be sure the lead-in wires are equal in length soxxinwqmi*-2 * that there will not be a time lag between speakers? Explain.

In the electromagnetic spectrum, what type of EM wave woud,dn k,+mn w;,dlgv9f; xkf:zld have a wavelength of9;fdm +, :dnv,;dg l wxfknz,k $10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound waves (20 Hz–20,000 Hzbvybufro x *kcss+dv(n 3 )921)?

Can two radio or TV stationwq ra3r v98rps31qr5.apq7 tms broadcast on the same carrier frequency? Explain.

If a radio transmitter has a vertical antenna, should a r2ms0p1 3bytl7mk.ckmwu 0me6 3yvc h6llg ,s 5eceiver’s antenna (rod type) be vertical or hy563 kcgesp.1htkl3 vm 0clus60,mwl 2m b ym7orizontal to obtain best reception?

The carrier frequencies ofdua: gut1j4g*5: i v3l 6yckfo FM broadcasts are much higher than for AM broadcasts. On the basis of what you learned about diffraction in Chapter 1vj5tcg::fa3y kodui6l41 g*u1, explain why AM signals can be detected more readily than FM signals behind low hills or buildings.

Discuss how cordless telephones make use of Et4+ -3u .pqote a8eifhM waves. What about cell phones?

A lost person may signal by flashing a flashlight on and off using Mor( u;tys un7f6nse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequency onu6t7yu sn(;f f the carrier, approximately?

  At a given instant, a (wds saflh/ile,px;bm65 g02 1.8-A current flows in the wires connected to a parallel-plate capacitor. What is th iwdxlm2 ef(l,;b50sp6s/agh e rate at which the 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 av1puxe(w +dg,q * 3zr2*sldvu traveling 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 oscillates vertically and has a frequerko 9x 8(zef/j;oqe 2dncy of 80fk(2z9qr/djoe 8; eox.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 p) jr(qx9lxa) cqd f4;a microwave whose wavelength is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of athme iq,f0chz275. f z $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequzdf:g5s1yt +;/k5eg wr djuk1ency $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength o(1u hajavd m *mtx b /;-)a/qdqqt9hq7kx2s2yf 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 tfwxtg w wry-2,.n- ,pho reach us from the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broadcast ban xmg+v/c1 bll+qxe5 c8d is referred to as the 49-m band. What is the frequency of a 49-m radi18lqclm /xx+ 5cbg+ev o signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light- mnd9o,n 0vn: c nj9lrpb4v,a,was n-1years away. That is, it takes 4.2 years for the light it emits to reach Earth. How far away is it in c90-p,19v ,onn n4n dsjv laa:rb,nwm meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distance (not timeirzglkb -d/1l.rxy4 6). How many meters does light travel y6l 1lr4. r-/ dizgxkbin a year?    $ \times10^{15}\mathrm{m}$

  How long would it take ty vuxp o sjv:w), d/qjtn+49m /pj1o,a message sent as radio waves from Earth to reach Mars
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to svliqeqd,, 5v6 xa n6s3cale down Michelson’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 mxs6l,i53,qn veaqd 6vounted 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 50.0 m away cqqhts 16kzvc g . 8v(yr/:9*yg4vhtkfrom the s(yvhz 4 :vy1cq/*8 srcvqgh 9.6tt kgktage (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 sh). ock7miin vud9ig7wl)cl s:9ct6 :j ort bursts of electromagnetic energy. If the laser light wavelength is 1mwl):l7k giu:v. 9 )coi nji7cd9cs6t062 $nm$ (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 wa.d a5ie)ky ymzq5k f h7(o)xf7ve 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 tran;g jl0 6fdj-xfsported 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:s g t8-v2)r2dxsp adng55qll from a 1200-W source. At a distance of 10.0 m, what is the average intensity, and whatrg2d t:v)g2llax5 s85-sd pnq 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 o 0(n0mo6 *yurrhm srf-68sn-xzvsg c+2s dl ;uf 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 f aj,-o sh8*idcield of 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 emllv zn3x,1:n e2/tiw jrg8(,zqb h .jyits a 1.0-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 pressure due to a 100-W bulb:+uqms s6v,kq 2a+mof 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 focvnmbi rnug 8-v2-aytb8 /8 d)r
(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 recegm/ j-hkt( xy k+ckv40ption.    m

  Compare 940 on the AM oez0bztbr45a wd q;*2 p6 ;4dkix3gea dial to 94 on the FM dial. Which has the longer wavelength, and by what factor is it larger?3adr*zzw0446it 5ke p2a obxeb;g d; q
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV channelsgkuh8nc6,gql,p( o )1 -9d i8oxpabqm that broadcast at 54.0 MHz (Channel 2o1b gcgq9p8hnlpkd,o um ,x-( 68 i)aq) and 806 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a capacitance of 2w/bj m:jc 0kn4wnvh45800 $pF$ 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 96.1i a,o2rt+roh ;-artj (-$MHz$ 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 fixed capacit(gank npg7ou oz-ik,/q -og6.or $C=840\mathrm{~pF}.$ 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/blsbt1oy b7npf*7 u/ndm g8,an tune a range from 141n n ,7l8bbpbsf t7uy/ogdm*/.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 power of 10 mg zfg,jcj060 $kW$ 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 of an EM wavy zn+g-l h93c;z5oot 8j(yf 0h)xkjqme. How large must the electric 0fjnj t9(y ho-zkxygcm3+ oh z 5;l8)qfield 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 radicacrm j1x-ms-u nk/er)6lly change its output, how long would it take for us on Earth to learn s6-1recx kjm/)n m r-uabout it?    min

  Light is emitted from an ordinary lightbul:g3nw tu ;1xnnb filament in wave-train bursts about w n1xnu3;tn:g $10^{-8}\mathrm{~s}$ 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 readu ,waywz8 :4ijt- y lh3ik.y+ch the first astronauts on the Moo-l. 8y +wij:wihd4 a yuk3tzy,n?    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 vsm8*i (kyav)bef89i 0jp(7su)vyjt zsgd*- Moon (Fig. Below) was beamed to a listening crowd from a radio speaker. If you were standing 25 m from the loudspeaker, what was the total time lag betpit iy8) *kjgy0med( vb8*fz (v7vu)s j-sa s9ween when you heard the sound and when the sound left the Moon?    s

  Cosmic microwave background radiation fills all spic9 r77lq ftm-im;quf vm4 60race with an average energy densi4irmr 7 flmitcqf9u-0;6m vq 7ty 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 Mars, knowing that s 1(tym sran()55p0vlfvml65 4epsoo the E oo sps rll(5fvae1 5(4p 0)nt5smy6vmarth 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 traveling EM wave is noteji.1qyq khy1 0d 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 energy flow is 1qy k0.jqyih 1$560\mathrm{~W/m^2}$ 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 anguxbq83- ( 8bmos hz;s0qb; ppf v,d;utenna 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 antenn80c bshkp,-fda that consists of a 380-loop circularfh-sp0c,b8dk coil 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 pamuq)1rbf 2s+jqhcx/) /1j 1 ui a8mhdsrticular 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 station’s transmitting antenna, the amplitude of the ele ) h*vc1t/cxkrctric fh* )xvtcc/k 1rield 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 sio- wd;k -(pon-9htldex plates connected together pnhd ep-dot9o;kw ( --llaced alternately between six other 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 allowed to broadcast at an average power notu2g5rq (emzj4+v 0pqz 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 energyag- hr8)a3 sj -p9c2n qm9t kma-pflv. uniformly in all directions at an average ratea .tgv)nsr-jl9cph -ka3mf 9-2a 8pm q $P_0$ 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 directions. bwks8tq ltn(3 e-mr29
(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 the station.knz 2r:fi,nias/jyoio 1t+c:p 0smkvx (;g 0;
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio statb9p31 7 2tfo+97nodfzzvka ui ion of Problem 52 so as to avoid electricnoi pk9o1 t7f93av+7 fbzd zu2al breakdown of air at a 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.]    $\times10^{11}\mathrm{W}$