The electric field in dk;,9 ,4cx82qu t hc wijws8oran EM wave traveling north oscillates in an east–west plane. Describe2u8 wh84jcoxc ds;ik, tr9q, w the direction of the magnetic field vector in this wave.

Is sound an electromagng6 sho d.9om9uetic wave? If not, what kind of wave is it?

Can EM waves travel through yp2u)r2 6yr) jydj5uh38p hd52q e1cqccpp0 ya perfect vacuum? Can sound waves?

When you flip a light switch on, does the light go ot4rpoj.p nz a /7ry89gn immediately? Explain.

Are the wavelengths of radio an:x5kx -ponuvw; ,w/ctd television signals longer or shorter than those detectable by the h p/x kcov:5wn-ux t;w,uman eye?

When you connect two loudspeakers to the output o; epfm zcir. jf)(b04n56are;kb:ui jf a stereo amplifier, should you be sure the lead-in wires are equal in length so that there will not be a ; ij;cr 46fkbf:iea5) nb u0me.jrp(ztime lag between speakers? Explain.

In the electromagnetic spectrum, ocs:bwf l5xq j( 5n )w*.bif+k7 mzv9nwhat type of EM wave would have a wavelength of jxb5)mc bqsfi z*7+5o:nv. 9lkn(f w w$10^3km$ 1 km? 1 m? 1 cm? 1 mm? $1\mu m$

Can radio waves have the same frequencies as sound waves (20 Hz–jk le8/ozsl s* 1rv3+jr geg8*20,000 Hz)?

Can two radio or TV stations /4lvcqt a61mhbroadcast on the same carrier frequency? Explain.

If a radio transmitter has a vertical antenna, should a receiver’s anten352zqqgd48ss3wu vdx na (rod type) be vertical or horizontal to obtain best rw3xg s4qu2q svd835dz eception?

The carrier frequencies of FM broadcasts are much higher than for AM broadcasts.hb+2 vi;: uq y5jw8ceb On the basis of what you learned about diffraction in Chapter 11, explain why AM signals can be detected more readily than FM signals 2vbe :; y5i u8wb+chqjbehind low hills or buildings.

Discuss how cordless telephones make use f+qw+s7) lv;xt8 ra i gm6ge,xof EM waves. What about cell phones?

A lost person may signal by flashing a flashlighdav8/llzx : a+njdmk9(os5;qt on and off using Morse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequency of the;k/m9 +zalo asx v dqn8j:ld5( carrier, approximately?

  At a given instant, a 1.8-A cj t /x p3l y1;iki6d)etwwu:kch,5q.vurrent flows in the wires connected to a parallel-plate capacitor. What is the rate at which the electric field is changing bk )q/uijt:y. l1hx;ik3 dw,65ctw e vpetween 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 peak magnitude of 17.wsvzl 6 8*+rxz5 $nT$ 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 7b; zhtdbm:.f a frequenz: fb7dtmb;h. cy of 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 wxjua; ptn)ej6 e4: b*javelength is 1.60 $cm$?    $ \times10^{10}\mathrm{Hz}$

  What is the wavelengthet4/uid92 r+jtsw7kw of a $29.75\times10^9-Hz$ radar signal?    $ \times10^{-2}\mathrm{m}$

  An EM wave has frequenc22vmnxe6ka :aav7 -c u2 d(cmdy $9.66\times10^{14}\mathrm{~Hz}.$ What is its wavelength, and how would we classify it?    nm

  An EM wave has a wavelenype+kic v mx*t95 ue6-gth 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 lighwudccu7 *vr9:r :e*ft t to reach us from the Sun, $1.50\times10^8\mathrm{~km}$ away?    min

  A widely used “short-wave” radio bg+sb6 0qt2m fcroadcast band is referred to as the 49-m band. What is the frequency of a 49-m radio +gstqc62mf0 bsignal?    $ \times10^{6}\mathrm{Hz}$

  Our nearest star (other than the Sey,vz-j r0g -mun) is 4.2 light-years away. That is, it takes 4.2 years fo0erv ,z--yj gmr 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 meterf vb7ezj)4za4g-gp4k2 ; ggffs does light travele4fpbg g g7)2v-agk;j 4zfz4f in a year?    $ \times10^{15}\mathrm{m}$

  How long would it take a message sent as radio waves from Ead3zyq+395u7de ttqxm rth 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 3 -v1vxe;tmsp to a size that will fit in one room. A six;m etvs-1 3pxv-sided mirror is available, 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 in the balcony 50.0 m adc;eg gd2h, a43jblomts8 f: 9way from the stage (Fig. Below), or a person 3mo,f 9hd: tge;82s34 ldg cjba000 $km$ 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 very short burstst s+u. .f0uir1mk r i9bv)3izj (pj)lv of electromagnetic energy. If the laser light wavelength is 1fr3)ki)su+1rzj( 9uv 0 itlm ib.p. vj062 $nm$ (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 5,by;0x; tfh itr,zfurms 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 acrossy7m y.rf2cv w8bl v;egmuw8.) 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 spreadoqc 4s3u1lr *mqi wp8.8bdc7 cing EM wave comes from a 1200-W source. At a distance of 10.0 m, what is thepwmls*18.qd8 rcc 4 7bui q3co 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 thq6 b0ibkpqrb h/7rq6 t j5u0a/e 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 an EM w j:rdy2g u5h(6yjh0jt+gfbm3uq 8 f+yave 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-lon;e9ak me(7hn jg 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 press. fx :g 63k2p-dtqfcrjure due to a 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 wavelengths fo/ rxrk s8ob5x z3c cm*:.fsju(r
(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 phone receptiwal.w*s*yakqv. )yed* kc8 a7on.    m

  Compare 940 on the AM dial to 94 on the )2o uo(ob5tl /-rgvwe a7:p jaFM dial. Which has the longer wavelength, and by what (gjao apbeowrlv-u7 : 5)2o/t factor is it larger?
 ----待选择----AMFM 
$\frac{\lambda_1}{\lambda_2}$ =   

  What are the wavelengths fz/v:o;els *n *8cnhkp or two TV channels that broadcast at 54.0 MHz (Channel 2) and 806 MHz (Cn p/ *znveos:kh c8*;lhannel 69)?
$\lambda_2$ =    m
$\lambda_{69}$ =    m

  The variable capacitor in the tuner of a;hzdpukec-lx 6q:5o1 n 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 96.1-* i36*ulza(*bmb t lej hq43bw$MHz$ 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 fixed m7w xo koc*ywv 9 . blg9gwzv51.1sqw0capacitor $C=840\mathrm{~pF}.$ 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 gubq*dq 1ua 7-can tune a range from 17udq-qba *1ug4.0 $MHz$ 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 wit;o7x+ i)gs2sc80 npe/2pjevt nmf7jth 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 antennaz2ll:h.95pain mvcn0 is oriented parallel to the electric field of an EM wave. How large must the electric field be to produce a 1.0 a2n.nhimv5l:p z9cl00$-mV (rms)$ 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 ra kty,f*mf/ mh//vv vi:dically change its output, how long would it take for us on Eartfki:/y/ *f/mhm vvt ,vh to learn about it?    min

  Light is emitted from an ordinary lightbulb filament in wave-train burstshh-2fi6fg w c6w5czz(go c55a about i(f6z5c5w5hghfzg2 ccw oa-6$10^{-8}\mathrm{~s}$ 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 reawly 58uwyu h(6 (k,htcch the first astronauts owh lu6k(yh,5wy8 ct( un 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 theh qxza4( pj 2b3t4 rywhc3; ,bx*ar;jnw g-,fp 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, what was the total time laght,-rp24;hqjy gzbwfa4jw3c3 (ar,b*xx p ;n between when you heard the sound and when the sound left the Moon?    s

  Cosmic microwave background radiativ pk*g6 l+ hq:eb/9xldon fills all space with an average energy dens/qlp +de*bglhk v6x9:ity 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 f ox+4irqmu b/+hcv1 ;. zrv0qin the sunlight that hits Mars, knowing that the m0fq rvuhcvo+b;r 1./xqi4 +zEarth 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 time, a traveling EM wave is nzg 78dyas, j*ok .c,qcoted to have its maximum magnetic field pointing west and its maximum electric field pointing south. In which directioc* yq.z7j s8a,codg,kn 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 u2 v/1he7y.g54iq rrbm6jqsqq.3e nl would have 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 a7ci cpsu2,7 nhn antenna that consists of a 380-loop circular coil of wire 2.2c 7 ,ipchnsu72 $cm$ 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 intensitit+hq- mo .9cptp2wk (y of a particular 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’s transmittcqxxx8e;+ mqi2),s jh9ah8m eing antenna, the amplitude of the electric fiae xcqex8 s+h qmi mjxh;92)8,eld is $0.12\mathrm\,{~V/m}.$ What is the average power output of the radio station?    $kW$

  The variable capacitance of a radio tuner kq 46f zn(.qsfconsists of six plates connected together placed alternately between six other plates, also connected together (Fig. Below). Each plate is separated from z.q46fns qk(fits 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 averagym6kv/l83yw qi6j ah6iso e,:e 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 uniform*l )g;fn7lgpw ly in all directions at an average rate)*p7lwfn l gg; $P_0$ 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 um7qze25l7tn m2b yl: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 aef lq1 vy 4he0*mou;y- distance of 100 km from the station.
(a)    $\mu W$
(b)    V/m
(c)    V

  What is the maximum power level of the radio smr :g3ykq7c n*tation of Problem 52 so as to avoid electrical breakdown of air at a distance of 1.0 m from the antenna? Assume the *rc qy:gn3k 7mantenna is a point source. Air breaks down in an electric field of about $3\times10^6\mathrm{~V/m}.$ [Hint: See Problem 51.]    $\times10^{11}\mathrm{W}$