The electric field in an EM wave traveling north oscillates in an east–wes lul2ikslbp+ h). q*3dko0e9 xt plane. Describe the direction ofx9hbosl q p3.+0u2d k)kle*li the magnetic field vector in this wave.

Is sound an electromagnetic wave? If not, what lv+b h tio*,z+xm44zvkind of wave is it?

Can EM waves travel through a oycf 9*6i;q e1sl zoy+perfect vacuum? Can sound waves?

When you flip a light switch on, docyb ph02gkr7 9 3uroeq)(ggx 1es the light go on immediately? Explain.

Are the wavelengths ofnz3n1r1s la3:)zdyhf*ko 8 wm radio and television signals longer or shorter than those detectab * fzn1osl3)8z ywr: 3n1hkdmale by the human eye?

When you connect two loudspeakers to the output of 0rglhak-oyl9k p ,m,f m. :ib*a stereo amplifier, should you loa, g,myi-pbr* hkk.mf l:90be sure the lead-in wires are equal in length so that there will not be a time lag between speakers? Explain.

In the electromagnetic spectrum, what typecayzzqm)q ( 3*cgg*4s of EM wave would have a wavelength of*azq *)g4( z3gcys cqm $10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have th8b0p2b sdwl(g3q*q a ue same frequencies as sound waves (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on the same cbqj ozs ukb,oi6+m lu/:gx2kfz 42:i*arrier frequency? Explain.

If a radio transmitter has a vertical antenna, should a receiver’s antenna/zfa.i:i 3jdp/z5ws n q r)f,npn os)1 (rod typ),i/fnnfjs. dp:z rwa1iszp 35 )/qone) be vertical or horizontal to obtain best reception?

The carrier frequencies of FM broadcasts arux znnz0( mj9mm-/ly(e much higher than for AM broadcasts. On the (mzz 0n-xml/m(uj9 ynbasis 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 telepj cy:nl91mgk1 i,qe.zi ps; y9hones make use of EM waves. What about cell phones?

A lost person may signal by flashing a flashlight on and off using Mor + 7s;fvbftah3se code. This is actually a modulated EM wave. Is it AM or Ftbhfa 3+7vs ;fM? What is the frequency of the carrier, approximately?

  At a given instant, a 1.8-A current flows in the wi1t;ox;vsir4 gcl.k* fres connected to a parallel-plate capacitor. What is the rate at which the electric field is changing betweenfk;l* cs ov1g; 4tirx. 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 traveling EM wave has a peak magnitude of 1kc )e ).o,yv/ amgwyk/7.5 $nT$ 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 verticav. sybek,l p7lg* ;a(klly and has a frequency of 80.7ls(yl kae, kb.*gv;p0 $kHz$ 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 wawh op/ pv7t43jvelength is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength o 7upxq9 c(9h nr,k*wmcf a $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequeia:8k3 oc 1wjsncy $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelen:0(l1 ,ytv ms,u aiihzgth 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 light to reach us from the Sun, yahaceg 1j nk.v(8b 4h09+kvq $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broaouby6v1n-t eq9+w(k y f3 idg3)v1yrrdcast band is referred to as the 49-m band. What is the frequency of a goi)qvyky(yt3 9+136- br1n vr wdefu49-m radio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-years away. That u 0zw-xa-elu +(p6lpi is, it takes 4.2 years fliae0xpz( w+6u l--pu or 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 distance (nodutjrbz .,,p*t time). How many meters does light travez ,j t,r*dpu.bl in a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio wr qy, -g(eingvhw2j ;3jod60d aves from Earth to reach Mars
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to scap yuf12j 7o4uhle 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 mounted 12 m from the rotating mirror. If the arrangement is otherwise as shown in (Fig. Below), at what minimum rate must the my7oju4hp u2 1firror rotate?    $\times10^6\text{ revolutions/s}$

  Who will hear the voice of a singer first — a person in the balcony 50.03rv:h8 rv mw8j m away from the stage (Fig. Below), or a person 3r8vjvr:m3h8 w 000 $km$ 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 an2bn4z ne9 yzi.kkb.a+ d medicine produce very short bursts of electromagnetic energy. + a2nn9b ky4iz.. zbekIf 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 has an rms strength 9xw f4r1* nwtyof 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 transportmeez vg-wb/1b mwy5f336k+bp ed 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 spread. mpany7cepj62oimg .8p;hh8ing EM wave comes from a 1200-W source. At a distance of 10.0 m, what is the average intensity, and what is the rms vg.8cjpp e 8n2amp o;.yihh6m7alue 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, gpc+k2x7ax8 zg7nv-a k iven 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 a5qy( 8aw/ua avn 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 bo1hb gh1rcqely b7t +p w/,qd5l+k75a 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 a-ke3mt oljbu4p1w(;b t 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 waplrv eyoqhvy((/2l 4-velengths 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 phone recep40cbj bu v;(g lgh/2o+so3s. w9n ip xfxb;pa5tion.    m

  Compare 940 on the AM zoli /he20jp1x7 ukki(q(m1j dial to 94 on the FM dial. Which has the longer wavelength, and by what pxh(( 2 0kmuj/1leojqi7 zik1factor is it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths fxh4vmjrg ;*;y s,ujck/x9 hx /qxb;5aor two TV channels that broadcast at 54.0 MHz (Channel 2) and 806 hygb5cuxrax9qm/ j;kjv4/ x,x;*h ;sMHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner o(r l u3tes8 5+kdtdmd*f 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 *ar9ae;)px;i xxvmt 4 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 tuning citg, b4gjjkby2 sbv7;ze;/ c)yrcuit 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 buildwn-:itkdys-8d+iypf; ( +4 y(d paf mv a receiver that can tune a range from 14.0kvt4+ fypmf: spd(d+dyy 8i- (a-win; $MHz$ 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 r4x3jw2,2/erzflb7oi wkilq; adiation 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 o -/ ,j5.f/swaufe rtifriented parallel to the electric field of an EM wav,fia w.5f/t s-fu/ejre. How 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 s4 5 lids;utqeld3 1/)yznpp0tomehow radically change its output, how long would it take for us on Earth to l/0y 3 tndtls)e1puz4liq ;d5p earn about it?    min

  Light is emitted from an ordinary-r:l jjc8 /ba *bdgvc qh4)re+ lightbulb filament in wave-train bursts about *jdjv+b)cbgh- rq8r:l/ cea4 $10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it take for ajl( s-6mkntc. message sent from Earth to reach the first astronauts on them.t(- c 6kljns 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 tgu:uf6bu narc ngzd;7 50y- 9fhe Apollo crew on the Moon (Fig. Below) was beamed to a listening crowd from a radio speaker. If you were standing 25 m f:gy0;afz5 dn6u-brc9guu fn7 rom 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 +z rod:/f cz/00hmybt91d l t n+/cpgywith an average energy density of0z +/hy yb9 md1 0zorn:c/pgtl /f+tcd $4\times10^{-14}\,\mathrm{~J/m}^3.$
(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 that96m.d kcte7k1p9- gz lnx3nqd the Earth renxe3d.69k- mc 9 pgntd71qkzlceives 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 pwmphbj5 ib0jg 5 s0oy0woy 8-hqj (:5l4dgb*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 energy flow gqo: gwm0po y 080 5jhw(idylj-bs*5b4 j5bhpis $560\mathrm{~W/m^2}$ 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 h(3nf- unzn hdep6qh.7ave 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 genera ;q xlu6ayndv4 :x2wpb-g3stjk** 4zqted in an antenna that consists of a 380-loop circular coil of wiru 43sbqj:-x6yg4 *2* ptknlx;zvd aw qe 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 particul;il+ xqh8bre. wo cduvnm+.2 vjok,; 6ar 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 q*+sjb,9 5hm- kgax jhtransmitting antenna, the amplitude of the electric field is hj-,bq9*h5m+ sj gkxa$0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner coot: :(ajmsaz+ nsists of six plates connected together placed alternately between six other plates, also connected together (Fig. za t:ja:mo(s+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 broa3l: biou2; brydcast 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 el59k6eou 1 i;k5:znmd t9nne unergy uniformly in all directions at an average rate9o9t ln: u 6 k5ndkzi;ne5u1em $P_0$ 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 b kj 30,xo7epsin 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 the station. 6hhen75lr97ltu kw go/wxo;3*uyi h )
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum pow b8:7le8lza oyrbm5 iwd98 g4/g )sc gyq2(lezer level of the radio station of Problem 52 so as to avoid electrical breakdown of air at a distance of 1.0 m from 8g: 7q 2l cwo r5m(yyzzeb lel9)/iag8d 8gsb4the 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.]    $\times10^{11}\mathrm{W}$