The electric field in an EM wave traveling north oscillatesk)(xok0r ksd8 in an east–west plane. Describe the direction of the magnetic field vector in this w 8ksrk0)oxdk (ave.

Is sound an electromagnetic wave? If notnjl gq0m9ecni -2.qti. 3augj u1e;4x, what kind of wave is it?

Can EM waves travel through a perfect vacuum? Can sound wavet*g9/re b3sjvi- t ozlwe * pau8kr81.s?

When you flip a light swiz(8t0 n2t*y,u -c gashlnzz o)tch on, does the light go on immediately? Explain.

Are the wavelengths of radio and television siah/w rmj1r flh6/fb- 5 v q123t.uutcdgnals longer or shorter than those detectable 1 h q3au2t/cl rt. wf-1m bd/6hujvrf5by the human eye?

When you connect two loudspeakers to the output of a stereo amplifier, shou sq0wkdkkj7 -++6uup u(0o vksld you be sure the lead-in wires are equal in length so that there will not be a vuo+k7ju6 w+ 00sq-skkukp ( dtime lag between speakers? Explain.

In the electromagnetic spectrum, what type of EM wave would have a waveleni7 s6hh6cq ti.gth ofsqhiih76.t c 6 $10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound wlmjz 2(d +4p uri4:mi)9ujrwraves (20 Hz–20,000 Hz)?

Can two radio or TV stv:drd6p7 ro 2sfr3az;q z+0adations broadcast on the same carrier frequency? Explain.

If a radio transmitter has a verticale-ct.k;yfu52zl mow m*1 5gh a antenna, should a receiver’s antenna (rod type) be vertical or hori5;a5*zw 1g-ey2 mmutc oh f.lkzontal to obtain best reception?

The carrier frequencies of FM broadccd w wxh+g( zhy1nob6(yk50 zh6am .p:asts are much higher than for AM broadcasts. On the basis of what you learned about diffraction in Chapter 11, explain why AM sik6 o(yanz m+.61hdg:pwz05chbxy( h wgnals can be detected more readily than FM signals behind low hills or buildings.

Discuss how cordless telephones make unhzo+r 8t6/v;9;ys/2kezyu.a gem rvse of EM waves. What about cell phones?

A lost person may signal by flashing a flashlight on and off using Morse code. T(oloe l:6m v(768w)sqmlk w qzhis is actually a modulated EM wav ks6l(q)voq w:6lo 8m(lwe7 zme. Is it AM or FM? What is the frequency of the carrier, approximately?

  At a given instant, a 1.8-A current r y,ydf2b1jb9rhln g/f 936rd flows in the wires connected to a parallel-plate capacitor. What is the rate at which 1y jbryhnd 3r6/9lg92rbf,fd 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 a traveling EM wave has a pzl/ txm +w,np wc41d+leak 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 aryi/3 xr:x euy2k9c; u frequency er/ yxcx:uu;2ir93kyof 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 wavelength is 1.ysmy:7xp qu5lk; 6k 9p60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of aihvl0w+4 c )3uqbzuu/ $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequencynchno * jz5k,0rvu;6: qhufq9 $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wav j4jec0xz 69wf0u(o w+ z(kmbgg)gx.celength 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 Su l vm(f;epe/+xn, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broadcast band ispdakpmp97); ;tqmvcb8qo-:w 87b q af referred to as the 49-m band. What is the frequency of a 49-m radio sicqvmq o) ;7a;p8-btk8p pfwd7bamq9:gnal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-ye pwn .uhe w8d0ly.ha.w, -aswll: 89kyars away. That is, it takes 4.2 y8al:ke- hlwh p.swlw d. 0 ,w9nyy8a.uears for 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 (not time). How many meters doey.5 akbi bp) oh;n+4xhs light travel ip. i +oy;4)5xna bbhkhn a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent t (5bgk3jn8lq 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 20 myc5lo4 cmjMichelson’s light-speed experiment to a size that will fit in one room. A six-sided mirror is availab42c5 my0olm jcle, 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 — a person i9bu4tq m4/qyih8v2k hn the balcony 50.0 m away from the stage (F9 tuvmby 48hih/4qkq2ig. 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 scienceunm1s 9w5d lxf n5-q772 bkcpj and medicine produce very short bursts of electrompc7njq7u2dw -k95nl s1m 5fxbagnetic 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 haszr ymg np ayk,n(jxf6+- /x32t 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 across a zk2,he hb6k9 t$1.00-cm^2$ 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 frbc .fjves*+ig .hr 1y,om a 1200-W source. At a distance of 10.0 m, what is the average intensity, and what is the rms value of theic.f ybs+1h*, vjr ge. 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, gimn0iekod.nu- )l4ly( ven 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 u 0od, rtmn0t y2j85(eqp;uevof 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 ee yyhd 2msw;de38 k m,77fvz4emits 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 1xugtbaz wr101ow3/ 0j00-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 a*kszhm7 2wz/xw2 m*d
(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 photvjdk1rh3052eqm nnl*r45 zcu2 bb;t ne reception.    m

  Compare 940 on the AM dial toddvk2+0 ;t gxf 94 on the FM dial. Which has the longer wavelength, and by what facv+tfk2gxd; 0dtor 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 MHz (Channnb.z3x4- zf vgjt 7l9zel 2) andbnl.9j473 ztz -zx gfv 806 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a c -c(;mz1a yal7o2 qltu:,rcv zapacitance 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 ltf14ctr.oz9w1xi b h*oh m +;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 circuit has a fi 3hp7jmzy/o1h :g 2o4thmcwk. xed 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 wish)3f-ioj4gxcr 2rlk q-es to build a receiver that can tune a range from 14.f)3c-lr-oi4 q x 2jrkg0 $MHz$ 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 radj(g6w;xm1g )no ,pe(b:ub g7r z,grcn iation 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 thpy 4:j w(p8cnyzd9 l3ze electric field of an EM wave. How large must the electn(z9: p3l w48yczjdp yric 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 outpc ,g dq0wpb8,kuhf06r pdco( *ut, how long would it take fo8u6k0d p ogcd0qc(r*p f bhw,,r us on Earth to learn about it?    min

  Light is emitted from an ordinary lightbulb filament in wave-train bursts abouto.2e,72ce5v ztz clv5or4fyf 5,fl4e5vv7c z2zfc.rt e2yoo$10^{-8}\mathrm{~s}$ in duration. What is the length in space of such wave trains?    m

  (a) How long did it take for alfivfy:sodiv/9 7lfx6jxzr - *8 :1gn0 tp( nq message sent from Earth to reach the first astronauts on the 9fnf otj *1dg/ llp768 f(xniysxi zv:vq0: -rMoon?    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) 0zltwyhiq 3,* 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 betwet * ,whqy0i3zlen when you heard the sound and when the sound left the Moon?    s

  Cosmic microwave background radiation fills all space with an average energy 2hr2lwp6ai/ p)sq)l k71 ,sa.uwlal o4lge 2 adensitr, p q6 lhau2l)2a4le)sswwlk1g pl2i/a.7 oay 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 hitsa w+w1uh24 0qx++ jk ogib:wuk Mars, knowing that thek0gaqwujh +wu oi w1 2b+x4k:+ Earth 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 ti t4)0fpoh6vj(,cc z kame, a traveling EM wave is noted to have its maximum magnetic field pointing west and its maximum elect6op fatv 04c(h, ck)zjric 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 tot(q)/ hvpls5lyv6 s2 mgj*sy* 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 of a 38qwsg / ilqd ()3p.m1z*j,pw1j a idyi:0-loop i( lz1.qg* :)1ia y,w pwid/jqp3 mjsdcircular 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’m**/woqdt s4ps 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 transmitting13hjar pf*g. 4r,4vzsv:lccr antenna, the amplitude of the electric field is vhc1apv 4r,.fcj3zs4rgl* r :$0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner consis,he2qgoc+v73 d wcx *kts of six plates connected together placed alternately between six other plates, als o32ekd 7* +cxchw,vqgo 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 allowed8kl7-:q 30yx fr mfcxi 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 unthxg9 i 4s)vqx32 ,rcpiformly in all directions at an average rate cq9hpvrxs)4g,t2 ix 3$P_0$ 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 stationbvo9uj7o*24iw qm zi6 emits 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 u033rt.sy eyu*9ikj z100 km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio station ofsu;wn u js94wl1s :x(c Problem 52 so as to avoid electrical breakdown of air at a distance of 1.0 m from the antenna? :4lj9wsucu1w sn s;(xAssume 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.]    $\times10^{11}\mathrm{W}$