The electric field in an EM wave travelin3chtizvrc0k;l7./i kg north oscillates in an east–west plane. Describe the direction of the magnetic;3h/l7 ck .vci0ikt zr field vector in this wave.

Is sound an electromagneticvwn9 mp x:-d; gqvp,j9/fc ;eu wave? If not, what kind of wave is it?

Can EM waves travel tft,z k*,ke 8cihrough a perfect vacuum? Can sound waves?

When you flip a light switch on, does the light go on immediately?u 2v:h3 )qh r(f; 0lgn0zsnacg Explain.

Are the wavelengths of radio :e7h:niaxz;k( :nph a and television signals longer or shorter than those detectable by the human ehinhxa:p;nkze(7 a :: ye?

When you connect two loudspeakek f 2xa;dn. +m5e8x.dmt+gucyrs to the output of a stereo amplifier, should you be sure the lead-in wires are equal in length so that there will not be a time lag betw5ayxe8md .;nx fdut2.+ +kc gmeen speakers? Explain.

In the electromagnetic spectrum, what type of68uuit43,vz( az w*6 naru epo EM wave would have a wavelength of ,4v6 uzowrnteau u *z638(pia$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound6cahb.o1 xtze0 5xq .:ecf:nm waves (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on the sm j7n0wnl.myhl tg*c3m.-5 pmame carrier frequency? Explain.

If a radio transmitter has a vertical antenna, should a receiver’s0z26ecgt( sojhz.-qa antenna (rod type) be vertical or horizsgza(qec.z-6ht2oj0 ontal to obtain best reception?

The carrier frequenctjjs+el-6sk h:r d lt f.;-oo3ies of FM broadcasts are much higher 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 thar.jfoht e; -s:sd +lkto3j l6-n FM signals behind low hills or buildings.

Discuss how cordless telephones make use of EM waves. wm(x9 b(rc:eeWhat about cell phones?

A lost person may signal by flasha3 :2-)nkql0c,byd dgk2 itq ring a flashlight on and off using Morse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequency gc,b :qd3y2)r2 0adiktq-lnkof the carrier, approximately?

  At a given instant, a 1.8-A current flows in the wires connecte+ev (so7z ;otvd to a parallel-plate capacitor. What is the rate at which the electric field is changing between the plates if the square plates ar+v osovt7e;z(e 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 magnitg;x8;:ji43u bt (f gdkity4fr ude 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 fqxhh/ yeh2x3- requency of 82h-x ey3hxqh /0.0 $kHz$ 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 myyui(t4 v:bb ;icrowave whose wavelength is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of a 7;5-yi9(ibb f ne;*osdtepvm$29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequency *cxpi b6x-mbiqj/7rv3qo i)gw c:74s$9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength of +ag 1+z)eapv an;q bt(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 from3; u/bo xs)vsx the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” r,ud5y4z5 elwi.t tql9adio broadcast band is referred to as the 49-m band. What is the frequency 4t5udlwl9qy ez.5,itof a 49-m radio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) isx gxz317 qs+pn g7e8pe+lx jg2 4.2 light-years away. That is, it takes 4.2 years for the li7g 2zpjx3pxng 8q+l 71gsee+ xght it emits to reach Earth. How far away is it in meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distancy7-ydryk7jv xjvg y:gl1k6wnk:( g0d1w2f c4 e (not time). How many meters does light traved:1gkk:6wyly 2 g(dy0kcf jxgr7 v 4yw v17j-nl in a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio waves from Earth to6m;dbu* my*wk reach Mars
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to scale down Michelson’s light-speegf ke) ojm:(6knvne-(nv9d k4d experiment to a size that will fit in one room. A six-sided mirror is available, and the stationary mirror can be mounted 1 gn-m9 ev e4 n(fkdnjvok:()k62 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 awlmqlthp6 ()m,gs 0t6gay )qt mm6pslt(0ggl ,h6 from the stage (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 ve4:ixeq 4 5slbiry short bursts of electromagnetic energy. If the laser light wavelength is 106 esb54lixi:q42 $nm$ (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 traveliqx p2i pc/ fu/u92yo,ung 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 transported acrzvuzxd9e 2ni 2n*x-0voss 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 comfr av8/3l( txies from a 1200-W source. At a distance of 10.0 m, what is the average intensity, and what is the l f3vrati8 x(/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 of the Sun, given that ab r 6d)m,t*atdjout $1350\mathrm{~W/m^2}$ reaches the upper atmosphere of the Earth.    $ \times10^{26}\,\mathrm{W}$

  If the amplitude of the B field of an EM wave i,p5j*jvj2nk8dx:y ch s $2.5\times10^{-7}\mathrm{~Т},$
(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 emitni 9 rng+ks06bs 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,(8f ,veveqw.zk98df o xz(pi -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 wavelengths for :l,nt/7qy: e jdcs(hf
(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 f:+iu5 (wi yr;)nq5km,ez ubwj or 1.9-GHz cell phone reception.    m

  Compare 940 on the AM dial t3/ 5 asof0bepuo 94 on the FM dial. Which has the longer wavelength, and by what factor is it larger b5/a0fp3s uoe?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV channels thajk(h w910iy bct broadcast at 54.0 MHz (Channel 2) and 806 MHz (Channe9 0jiyhbkw 1c(l 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a capaa 3i-.fi oi1j /ptki3ncitance 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 96n j(,ia 8u-s:rp-tz yt.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 cir uzf.s-r)2 pamu)hm p)cuit 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 too gv/r8lrf, i t4+:o6al*n vln build a receiver that can tune a range from 14.arvot ln l8+lo6*i:4/, fr vgn0 $MHz$ 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 micr5gr* g)s 7c(vxa g hpqi2dw6i6owave 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)zx u*r 2hebjh,xd-rm+ -q0 py electric field of an EM wave. How large musr2rp )xex0 qm ,y*h-u j-dbzh+t 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 s br6(rm:w x)maomehow radically change its output, how long would it txw(b m)m6rra :ake for us on Earth to learn about it?    min

  Light is emitted from an ordinary lightbulb filament in wave-train bursts alvrqfq,, rf/kkojoj96 -s 00u bout ,0-9 l, q6 kv/jrfrfjkquso0o$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it take for f1:cxjeo 6d *dg x2s.da message sent from Earth to reach the first astronauts on the fd: xd2c16g jxo ed*.sMoon?    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 Moon (Fig. Below) was be,jhz.,ug 0a : v37hdov hui.wtamed to a listening crowd from a radio speaker. If you were standing 25 m from the loudspeaker, what was the total time la,3v.z 7o t wudjhhgha,0:uvi.g between when you heard the sound and when the sound left the Moon?    s

  Cosmic microwave background radiation fills all space with an average enery/l h4 5b2 -tsnsa0wnm8v)mhqgy densihmw ts) 02smvq/h4na8- bl5ny ty 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 thej e,;a ;u9xzd izu17n+ijayp4 sunlight that hits Mars, knowing that the Earth receives7i ;an4uz;ye9ai,+xu 1 jzdjp 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 EMle hcg4c.;ah+q w*fb+ wave is noted to have its maximum magnetic field pointinga*e4 +b c.lqgf h+;chw 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 ;vcq9 )+tw5v sns;prhbe 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 consists of a 380-l9hm,3o/ oe.mropxb 2dti. 3pnoop circular coil 3.o x3/mtd,bho 29p mipneor.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 ikeu9 l4peg50 4w hf305vlw; ntf.gi dparticular 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’sm mkp) hx2le0zxa pyez/ b0092c h9xt34 qzfx1 transmitting antenna, the amplitude of the electric field is/xxlxh2afmz1zep09tq 3 m2e 4bh9)cy0x0zk p $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacita4l qncalz edn65 qkay185 h*:snce of a radio tuner consists of six plates connected together plal8q aqd5ney:zkna65s41 h l*cced 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 not to exc0a ;z1kjic*b6 p*e3lq1yzckv eed 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 all directions at an avern n/ ;kv, v ;dvarkcs rqnasc:w6e/p)+;5ctz6age rate6n5k tw n+p);rvcezcv:kn6da ,/v/qr; s;s ac $P_0$ 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 emitsszw.)8dur1tfw o/ ;dsy4x6a d EM waves 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 the station. 8cm0l de (4zknuv9w +8 cn5aak
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power leve /4*0vuak-icbukoj w4 ,n c(nll of the radio station of Problem 52 so as to avoid electrical 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 electrun0-4a*i nc4,c/k(vbul jwkoic field of about $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$