The electric field in an EM wave traveling nov. 5h-u4 iojupcn x08aalflmqp)q2 o50tt35 b rth oscillates in an east–west plane. Describe t55)t0j5o2f0.3pp-mclouhqqalx i a tu n b4v8 he direction of the magnetic field vector in this wave.

Is sound an electromagnetic wav3s xha 4oumb ,(gzwj(0e? If not, what kind of wave is it?

Can EM waves travel through a putbsistk :m*5keb dw*;oo72 9erfect vacuum? Can sound waves?

When you flip a light switch on, does theu5p6 axcd5loq8ixc63e1,ti kj de33ju 9s0xi light go on immediately? Explain.

Are the wavelengths of radio and television signals longer or shorter than t)f u pbh,* anvf2u3vh1hose detectable by f v v)af*13u p,h2nuhbthe human eye?

When you connect two loudspeakers to the output of a stereu1h4*o d+ am9o t3qflpgn) hb5o amplifier, should you be sure the lead-in wires are equal in length so that there will not be a time lag between speakers? Explamngl3)f ob1ph to*59a qh +4udin.

In the electromagnetic spectrum, what g9oudb s//ah3type of EM wave would have a wavelength ofsag/9bh/ u3od $10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound waves (20 Hz–20,000 Hz)km 3w k .8dg6pah1.rxx rpkfwr35 0x5q?

Can two radio or TV stations broadcast on the q 0;*1 9jh1 n;tqk r;zvvtnovisame carrier frequency? Explain.

If a radio transmitter has r 5wj;gc s6;0vuzvags4)z+c xa vertical antenna, should a receiver’s antenna (rod type) be vertical or horizontal to obtain best recgvz0 +; rsucca)4vxg6 j;z s5weption?

The carrier frequencies of FM broadcasts are much higher than for AM broadcasts.:yovl2 z9gzkmcfz4 () On the basis of w yg co(:vkz)4mlz2zf9hat 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 telephones make use of EMug kyu ,w1l wip.cr:jf 7l,l2: waves. What about cell phones?

A lost person may signal by flashing a flashlight on imn6p h7c 2qa0and off using Morse code. This is actually a modulated EM wave. Is it AM or FM? What is theni 7 qh6acp20m frequency of the carrier, approximately?

  At a given instant, io lw5v( 1foofyr3.(z(2i moxa 1.8-A current 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 are 1.6 o( i o3(.i2voy51xfwm f(lorz0 $cm$ 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 trav fv *7lscy2eof0j7xm(eling EM wave 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, the B field oscillates vertbzg7,qf8 3 mlxically and has a frequency of 83g qmzxbl8 ,f70.0 $kHz$ 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 8/v /r 0 psdt8 gsb09xtr7ksuhmicrowave whose wavelength is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelength of a )dql t;b76fqt$29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequenlo:c6 o2 .jriacy $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelength of 650wc9qk/e3 j 1y p*hbz0l $nm$. 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 *az+ enr qpoakn5)i+9u c-2alreach us from the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio broadcast bandz9 7dqnv+d;o d is referred to as the 49-m band. What is thq7nod9z+ d; vde frequency of a 49-m radio signal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sun) iyz5xz xub pun 3ct)76hqz- i) hwj77f,s 4.2 light-years away. That is, it takes 4.2 years for the lh),w3 uzuqp j77x bh-x67y)c5z iftnz ight it emits to reach Earth. How far away is it in meters?    $\times10^{16}\mathrm{m}$

  A light-year is a measure of distan +,7dkcuu/4lq -1xcnamtra i l94 nen;ce (not time). How many meters does light travel in7tam qalkr-i ceuln,;n9c4+ d un/41x a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a messagegu/-jz vavw ;c0ebw+x jf 8:/o sent 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 Michelson’s light-speed experiment to a sizvpb*fg8-7-r 0; d c wyjzeru*ee 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 show08pgrfu* 7rd-z- ;j b *evewcyn 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 th3qmr7a im s 1wmf)ki;/e balcony 50.0 m away from thi ir)1s/ k;aqm3mmf7we 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 +9uq9 b)mshnband medicine produce very short bursts of electromagnetic energy. If the laser light wavelength is 1062 b qs9u )9hm+nb$nm$ (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 ax(h.hm*w ps 6rms 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 transpo3 0 (etmahsof7rted 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 spreading EM wave comes from a 1200-W source. At a dista*ig.vfhl ou-qe67h / 8d x,jtcnce of 10.0 m, what is the average intensity, and what is the rms value of the electric field? fxhuig7cl6j*d8-q ,.v eot/ h
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 tg2g5rmygs83 z he 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 fix )io+r1j 7qaxt/p5 mv pghvc(fl6bd s977xp5eld 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 ofda(0nv ty758s/f ni qx 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 k/ *srrxeav:6a 100-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 wavelengtg1.yq f;vq0g5(s wph5pgc0b chs 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 p pu+7 t mcjlf7te)nyx;p*o+ 8bhone reception.    m

  Compare 940 on the AM dial to 94 on the FM dial. Which has thejsc2h8htv+ 2t longer wavelength, and by what fah8 tcvs2jh+ 2tctor 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 (Ch12zaqr4+yj4(ff; t u2cn pkwgannel 2) and 806 MHz (Chj4 u4rptn(gzk;w1+cy2a ff q2annel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of an AM radio has a capacitance of 2 4xcx3 9 p(f6ee b.z59ltc2wkgpeq ia2800 $pF$ 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 9unfgv *.qt; pu4uo;5g 6.1-$MHz$ 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 hae+6 f2qc vak9es 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 2gi zb/zs -6vc(znlbu(o /z i3a range from 14. obz(zzsnz/ vicl 36/ -b2iug(0 $MHz$ 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 p q9fwq3nyk 1tx xf5u7;ower 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 orientedwa6,l24v1mu yr4nz s r parallel to the electric field of an EM wave. How large must the electrica12r,r4 mly zwuv4sn6 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 lo2 o w.-l;p8ytabwoz/7lg tf ms-/dm 5zng wo;l5stld-mwpaw bt z-m/zo g78/.2oyf uld it take for us on Earth to learn about it?    min

  Light is emitted from an ordinary lightq:7 k0vl ;jd9(nawahkhjv a20 bulb filament in wave-train bursts about akv ah09 dlnw;q7 2h:j0k(jv a$10^{-8}\mathrm{~s}$ 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 to reach the first wp6a bab5k9s-astronauta6k aw-9 bsbp5s 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 f b3xwgl31-4mqg fyl,from the Apollo crew on the Moon (Fig. Below) was beamed to a listening crowd from a radio speaker. If you were standing 25 m from the loudspeaker g mq33fgl-1xyw,fb4l, 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 with an average energy de;yzigl x69ie5nsity of ixyez9i;5 6gl$4\times10^{-14}\,\mathrm{~J/m}^3.$
(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 fieldeq8 q:cxfa tpx(9ep:1 in the sunlight that hits Mars, knowing that the Earth qpx:ec:pe9x f8q a( 1treceives 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 maximum mag:d8ps6oxpb2m, .m mycnetic field pointing west and its maximum electric field pointing south. In which dire6pbxos.pm8y :m2cm,d ction 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 k kf5, bud,prov3h) -qbe 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 ak ks99)m/avg: y sxg2 xukze2- 380-loop circular coil of wire 2. m9 ga2ge2ys:)z9 kk- vskx/xu2 $cm$ 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 signal is j16jdas61(*6hcxt.nkv 8l+qow9k kjq*muy s $1.0\times10^{-13}\mathrm{~W/m^2}$ 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 of91pojh8rt g:5wqxmv3 the electric field isrmpqow j3x9t1h5 :vg8 $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a raditsyn sl-q 56on61b 7:,yybucgo tuner consists of six plates connected together placed alternately s5c qylb6 n os1ub,yn6:g7ty-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 powera4 js 0nx;9v0reot 3nq 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 uniformly in all directions at anw38pgjqe:dn9x -w16c0 w xvxj average rate -wq89:jp gwvndxcew 6 3x10jx$P_0$ 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 directions. . cyfnev2 27qpsc*; un
(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 10 j .jy44pucd9i0 km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of th:yr;n nx 6h,wwe radio station of Problem 52 so as to avoid electrical break,r 6wxnwny; :hdown 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.]    $\times10^{11}\mathrm{W}$