The electric field in an EM wave traveling north oscillates in an ee9 gcy:x3 e /vrky3kj.ast–west plane. Describe the dire/ c.:y3v9 erkjgky3xection of the magnetic field vector in this wave.

Is sound an electromagnetky tz,v0d8yfv7 *7w z9tp fet/ic wave? If not, what kind of wave is it?

Can EM waves travel through a perfect1f (wegtx)o*5g0lal o vacuum? Can sound waves?

When you flip a light switch on, does the light go olcl/s. (qfw.ith8fafc +0a l. n immediately? Explain.

Are the wavelengths of radio and television signals longer or shorter thanv54hn-+ rnt4rrsu e awtf/ 6;i those detectable bytrw nr4u6rh/ e-n f4;ts5av+ i the human eye?

When you connect two loudspeakers to the output of a stereo amplifier, shoud+ e a45s)gbnwld you be sure the lead-in wires are equal in length so that there will not be a time lag bbwen s )+d5ga4etween speakers? Explain.

In the electromagnetic speck3vg 8 ;9bdfaetrum, what type of EM wave would have a wavelength of8kd;bg e 9fva3 $10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same fnlk c2fb195kh+f+xky requencies as sound waves (20 Hz–20,000 Hz)?

Can two radio or TV stations broadcast on xlm)8k+ eaasp/eejya l17 d2 ;the same carrier frequency? Explain.

If a radio transmitter hgootwcynbklbl4,:i. e7) jz 0os3 , 2oas a vertical antenna, should a receiver’s antenna (rod type) be vertical or horizontal to obtaing.io3)ls lo bz, ye:,7w2ctob o n4jk0 best reception?

The carrier frequencies of FM broadcasts are much higher than for AM broadcashgad, q+(,m; m+usexots. On the basis of what you learned about diffraction in Chapter 11, explain why AM signalsxsae,go, mm +h+qud;( can be detected more readily than FM signals behind low hills or buildings.

Discuss how cordless telephones make use of EM waves. What about cell ph44mwh-w p krs.ones?

A lost person may signal by flashing a flashlight 61pu1 xqabpq7 on and off using Morse code. This is actually a modulated EMb1a61qp uqp x7 wave. Is it AM or FM? What is the frequency of the carrier, approximately?

  At a given instant, a 1.8-A curren 75jtc*nck zt:t flows in the wires connected to a parallel-plate capacitor. What is the rate at which the electric field is changing between the plates if the square plates arzkn*5tcjt: c7e 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 17ijl); .lr3e wm.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 andm3wze(e h (,q*pvh-gg has a frequency of 80mzh* (gevpeq-,h (g3 w.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 wavelength is 19x 2, m +a7kzaigoo7cc.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of a i.qz k/+1ah srnp+odz,13 (dpr lne y6$29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has freque vtrqt/ 6-s 2l0fuk.5 tgydag9ncy $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavg5g.x ih jg5v(tg7rdlt(j8j 4(90khn mpl8ks elength 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 v1,l(tv 2fo ddz n(cu8the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broadcast band is referred tol wj86y0 :xq d eygt*ttwmic;+5n.,v v as the 49-m band. What is the frequency of a 49-m radio sl5 :xe + 0gitdmqj6vww.,tvt;cy y n*8ignal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-years away. That is, it tal /yb--m jkliokrwd,4pu ps 3lt) :42lkes 4.2 years for the light it emits to reach Earth. How far away is it iop:44rt,wll-p23u lk /s lkmbj id)y -n meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distancekjc490 x :(maw6 lmcadtx2 hz) (not time). How many meters does light travel in a yekdx a: z049w2xchja tm)m(cl6ar?    $ \times10^{15}\mathrm{m}$

  How long would it take a message hp1 jsw8a03 ant4fh9 fsent as radio waves from Earth to reach Mars
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to scale down M(jkdy,a0n *vf ichelson’s light-speed experiment to a size that will fit in one room. A six-sided mirror is available, and the stfv0 *yd a(,nkjationary 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 singq5hnc*yg) +0 s hoc63gpcmw6fer first — a person in the balcony 50.0 m away from the stage (Fig5ncmo6 hy+6wgs g0)fh 3qcp *c. 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 0e 8yoo+ ,kbsu sd*l9eand medicine produce very short bursts of electromagnetic energy. If the laeoe*yud,0+ s9 k lsb8oser 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 of 28.eujrlowg9r .ko09r5 x06 m2oh5$nT$. 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 attz c*zr.ms, (cross 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;l 1mp5h 7k0smm;fl ec EM wave comes from a 1200-W source. At a distance of 10.0 m, what is the average intm0lehmmsk cfl;175;p ensity, and what 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 of qqfxq+rca8e y-u) ; n844zu anthe 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 of ng k+l7io fp /1xcu5w7an 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 t s.z kcl ou-e4vtc 4(z,judw6e-et(7emits 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 e)tyb/n*f ftu:2w9u tbulb 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 fo-qy5,k*upb(kx2.lf6 mci fdpr
(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 phb.qp61z 9j aim7or4v fone reception.    m

  Compare 940 on the AM dial to 94odf:a*yrd9 e4tn 7h) h on the FM dial. Which has the longer wavelength, and by whaty r)*7h ftnao49edh:d factor is it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV channels that broadcast at 54.0 yf,9c/ma9og+ofibz8 MHz (Channel 2) and 80mi9 zbfgya, c8+fo9 o/6 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor ih:tv w p.,gd-ln the tuner of 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 a5/t *l.nc4pdp rl.kb 1gyzjih jx4l( rjk6,296.1-$MHz$ FM station has an inductance of $1.8\mathrm{~}\mu\mathrm{H}.$ What value must the capacitance be?    $pF$

  A certain FM radio tuning circuit cau37+(ndm*5 xk khj)o a:fkqhas 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 -06fy1 -3o qaf,*ttt0r8 jmmfakv mrv build a receiver that can tune a range from 14.0q offmmr ,m 60 *-ktt-3j8vyar at1vf0 $MHz$ 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 kzx.b7re i/+z$kW$ 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 oriut: +-hs5vui(il;p b eented parallel to the electric field of an EM wave. How large must the el: +evi usui(plbh-5t;ectric 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 output, how long w 54mx2, xipupuould it take for us on E4ppi u,52 xumxarth to learn about it?    min

  Light is emitted from an ordinary lightbulb filament in wave-train bu9(gy i qp2 9c:4/blflm*w .jbbzrqm2 orsts about 2 9jlgl92b/y wb: qzm4(i*cpro.b qm f$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it take fo+wtl :c3yc+rdc9fj g n l:x+g(r a message sent from Earth to reach the first astronau++n 3g9yf:ld( r xct+g :clcwjts on the 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 the Apollo crew on the Moon (Fig. Below) was beamed tohrew8; (p*0oy pr- cuw a listening crowd from a radio speaker. If you were standing 25 m from the loudspeaker, what was the total time lag betwer-c;(or p weh08yp*wuen when you heard the sound and when the sound left the Moon?    s

  Cosmic microwave background radiation fills all space w a 57hccu4bipft2*w xmhu(mg)(3 2p ncith an average energy density ofimf wc(gahncp53uxm 2b2p(c7*4u)t h $4\times10^{-14}\,\mathrm{~J/m}^3.$
(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 ty bps2e+ib :y8hat the Earth receives +s:p8e 2bbyiyabout $1350\mathrm{~W/m^2}$ 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* gteu;l-q 7py wave is noted to have its maximum magnetic field pointing west and its maximum electric field pointing suqpg e7*-y lt;outh. 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-,lacam*;3fwm c;atc zzw. z3 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 consists ofta) :,xnsw ij9 a 380-loop a,9)xs tw:ij ncircular 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 particular TV station’s siesc6g(g4iexty4. fd7y x +3btgnal 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 ante wdln n9p,)3e kcbs(6 q8h(fch0nv h*mnna, the amplitude of the electric field is wsldv0(,nfnkhhm9hc c*b n3q)e 6 (8 p$0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner consists of six plates connect (bnu ,xeyx) vhk:oz ( ,fclypb6/yok;c**3oxed together placed alternately between six other plates, oe :3*/*zylk6(nh;p cyyk,xxcbvb, uo oxf)( 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 exc82js9+utb0xnl6be vur 5+xx( ul bzx +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 a ma6 n8;z rxfc/lk8jf;n average rate8 a;6 8xfmrn;kjc/lzf $P_0$ 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 dir ;grad35a4 zk7bc 5lbtections.
(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,7muqlw mow*v i.v*f/,ml:yluix r7o0*iow . from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of*m-4o(9jfeuw kp i;if 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 anteuf4o*wm ;9ji-( pfeiknna is a point source. Air breaks down in an electric field of about $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$