The electric field in an EM wave traveling north oscillates in ans8r t pa,cgk53e1 ,uvm;) s2choaciw+ east–west plane. Describe the direction of the magnetic field o,uak5 cr1pa3hi)8+2mc ;s , c tsgvewvector in this wave.

Is sound an electromagnetic aa v;k:2a q(ctvq o jj669wnpneu6m91 wave? If not, what kind of wave is it?

Can EM waves travel through a perfect vadn:x2 mewk8h c8, s6 d9kzur* q7dv+fscuum? Can sound waves?

When you flip a light switcfcl9 ebg9( -zlh on, does the light go on immediately? Explain.

Are the wavelengths of radio and television signals lo)b e,xb8tmgr*x 7gfqllb q276nger or shorter than those detecg )x q7fx6blq2r tm,le8b*7bg table by the human eye?

When you connect two loudspeakers to the output sow5e;6)t ov2vo2 bleq 8ln.2y5bf dwof a stereo amplifier, should you be sure the lead-in wires are equal in length so that there will not be a time lag bet2dsow f wl vnb25te . 6lveb2)oy85o;qween speakers? Explain.

In the electromagnetic spectrum, what type of EM wave would have a wavelength 8(-vwv*+l pe(g c oovqkaucm- .+f)slof p-wq+k-( c.uel fog()lo vasc8v*v+m$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies ,-iix 0k )wdhl4d0 spoas sound waves (20 Hz–20,000 Hz)?

Can two radio or TV stahqfpwx16cn,y1gpm 0mnf1u *l- 0h:by tions broadcast on the same carrier frequency? Explain.

If a radio transmitter has a vertical antenna, shou n ,i14yinxhi;ld a receiver’s antenna (rod type) be vertical or horizoyxhiini;1,4n ntal to obtain best reception?

The carrier frequencies of FM broadcasts are much higher than foemxdccowr;3i(8d / n 0(sfe8lr AM broadcasts. On the basis of what you learned about diffraction ixe w(8;/dcd i3cfmlsone (80rn Chapter 11, explain why AM signals can be detected more readily than FM signals behind low hills or buildings.

Discuss how cordless telephones make use of EM waveddgn-;a7e33fcb-ya 2ffdm 2 ys. What about cell phones?

A lost person may signal by flashing a flashlight oni7yf c4g)i hsnvqlx 48t4mi-. and off using Morse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequency of the carriery c-ifngi hq 74 844)ltvsimx., approximately?

  At a given instant, a 1.8-A current flows in 6u.ax-cc v .xrthe 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 are c6r x.u -vxca.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*k bx- i7 0h3pr3j/r0psgtabl 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, t. qk,ckv,pd(rhe B field oscillates vertically and has a frequency ofvd,.cpqrk k (, 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 wavelengtn 207jcgzgfn1 h is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength owoxgfl-2ml4j* (f z rb2mz8x2 f a $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequency 3odzrr7f 7x,td9ff yl :vjd9 9$9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a waveleqq hx,0e:tgt 778qfk- kmesb:*oba/ tngth 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 tx hauy2)8,gu vojk1o0o reach us from the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broad, hiu :3zo5ujm9tz 1ebcast band is referred to as the 49-m band. What is the frequency of a 49-m radi9zmuub5 jie o,:z1t3ho signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) is 4.2 light-year2 ky ms2 sxl+ugs0o;6qs away. That is, it takes 4.2 years for the liggmo;l22 ksu+sq0xy 6 sht it emits to reach Earth. How far away is it in meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of dis5s-slmwt5)3 g:m bhoq(s vg8dtance (not time). How many meters does light travel i5qssst gg(5b mmv3dlowh8) - :n a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio waves from Earth to reach Mar ur;jfd;vl90)lcy 9gnz; vtq8 s
(a) when nearest Earth,    s
(b) when farthest from Earth?    s

  A student wants to scale down Michelson’s light-speed expe +6/4 ori3b9.ykva ei(sdzjh driment to a size that will fit in one room. A six-sided mirror is available, and the stati6vd9(iz o.3 ek/ajs byi rhd+4onary 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 voieo5b,qr6,yy*mw,0pa uh- vwq ce of a singer first — a person in the balcony 50.0 m away from the staho- wqmu 0p,e6 *b,vqyywr,5age (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 iw59ad0hp od /of2qz f3n science and medicine produce very short bursts of electromagnetic energy. If fq5afdp z wod3ho29 /0the 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 -e,;zd hch/lmrms 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 acr7lszeqo))5e*idzz r ) oss 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-, uj mmuc 2m(yq;1twe wave comes from a 1200-W source. At a distance of 10.0 mmy;1- jm 2,wmq (uutce, what is the average intensity, 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 the Sun, .qh;,lv6 yyhr/v qbd6given that about $1350\mathrm{~W/m^2}$ reaches the upper atmosphere of the Earth.    $ \times10^{26}\,\mathrm{W}$

  If the amplitude of the B fieldzhcjf. g4mf:lbn0 p98 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 emits a 1.0-ns-long pulse of average poweem,4ovl t(lycw4vvqi7- t w42r $2.8\times10^{11}\mathrm{~W}.$ 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 bo3ks2,na as v.ulb 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 e6s ocg (ejwq t-gs8k39/nxlf4 :faj*
(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 fory*sqe 6o+qy32y vb8cq 1.9-GHz cell phone reception.    m

  Compare 940 on the AM dial to 94 on the FM dial. Which has the longer wavefhmf9o ( er/imlysa.:z3(vbq 0: kk8glength, and by what factor is it larger? 8( /93vzoahmr s:bmk.effq0 ygi: k(l
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths for two TV channels 9xet6kjj- 6vdthat broadcast at 54.0 MHz (Channelvxdj6 69tk-j e 2) and 806 MHz (Channel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an Assocu o4 1n -qv//kd0hx+ am1 h9i/o: kf-jjbxM 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 96c lt*sj-gm u:u,)pts 5.1-$MHz$ FM station has an inductance of $1.8\mathrm{~}\mu\mathrm{H}.$ What value must the capacitance be?    $pF$

  A certain FM radio tuning circuit8 qc deun+jtep8+7z7y 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 build a receiver that can tune a range bwgzh)m 6wb4fr( 3 7lxfrom 14. h(b4zf7l 3bmgw6)rw x0 $MHz$ 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 1:s; l953c63 i ojvu)a2yrpzc*ai7egyb, vgmn 0 $kW$ 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 go.we.,5pmcy oriented parallel to the electric field of an EM wave. How large must the electric field be to omw 5, p..gcyeproduce 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 0 evw(z. w9ra1tok b-eoutput, how long would it take for us on Earth to rae.-zwb1eto0w v9k( learn about it?    min

  Light is emitted froc .v8:kbilvtwd5 , 2dqm an ordinary lightbulb filament in wave-train bursts about :q 8.l5ditcvk2dv b,w$10^{-8}\mathrm{~s}$ 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 z-8s3x ui(whd to reach the first astronauts on the M-w hx3u ds8zi(oon?    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 ez hf9u/1q,git a9 0mpMoon (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 between when you heard the sound and when the sound left the Mozp/qfm9 9ea1it ,g0uhon?    s

  Cosmic microwave background radiation fillslhcr; k82 :usgpy3ac7 x//jas all space with an average energy density of spk /cr hay /:a7ju8 xcs23;lg$4\times10^{-14}\,\mathrm{~J/m}^3.$
(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 sunv /x65g ejgz;p +fqpj(light that hits Mars, knowing that the Earth f p/5gzqpjx 6g;j+ (vereceives 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 noted to have its maxixh0ve9p h-;um- ui dk**wf 1efmum magnetic field pointing west and itwuik**u19 ehfp xf-; dhm0v-e s 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 havexpgad8:) oop 539:t z l -do)e9yqvgmg 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 an 9ly;m zs1ug6xncg :s*tenna that consists of a 380-loop circular coil of l:g uys6gxm n9sz*1;cwire 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 s;ylr .w20sljstation’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 tt2gh do)50ee lhe electric 2)tdl0ogee h5 field 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 six plates con t.i;oawc(f g/2fh irm1 ;cap1nected together placed ali;hc1 at.;f1(i pc2w/g ra ofmternately 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 exce2e i:3fo(:ribi8o(j 5uiggd l ed 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 k nkc)g 6q wa2 alx.ab )4g;fdd+b3,qcenergy uniformly in all directions at an average rate a,a+l kgqdbckwq2 a)6 cg3f)x4.dn ;b$P_0$ 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 directionr0vr+5 6b,(xz7 nbbaujortubj + *o t)s.
(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 dist ;vlm6ge (wn4b kjz(s mf5snua7 3-:zeance of 100 km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio station of Problem 52 so)qr 3dn-fpno4 as to avoid electrironqnp -3d) f4cal 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.]    $\times10^{11}\mathrm{W}$