Physics Unit22: Electromagnetic Waves - 51fly国际课程 (51fly.win)

The strength of both the electric and magnetic fields iwlcy+ dtx h4u1w3hjh3avw 5ko)cw2)(n the radiation field are found to decrease with distance w jkcad hv4h3( 5xco3ylwu1 h)w2w+t)as

A. $1/r$

B. $1/r^2$

C. $1/r^3$

D. $1/r^4$

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单选题 ( 1.0 分) 切至整卷模式搜藏此题

The $E$ and $B$ fields in electromagnetic waves are oriented

A. parallel to the wave's direction of travel, as well as to each other.

B. parallel to the waves direction of travel, and perpendicular to each other.

C. perpendicular to the wave's direction of travel, and parallel to each other.

D. perpendicular to the wave's direction of travel, and also to each other.

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单选题 ( 1.0 分) 切至整卷模式搜藏此题

An electromagnetic wave is traveling t: ro-0qlq +bd3n 10in*feaoc*hd7beoo the east. At one instant at a given point its reo*q *o+bi-q70dnnho: bc3 l0d ae f1$E$ vector points straight up. What is the direction of its $B$ vector?

A. north

B. down

C. east

D. south

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An electromagnetic wave is radiv/ / z3qdyrlms 1i0 73j)glhndated by a straight wire antenna that is oriented vertically. What should be the orientation of a straight wire receiving antenna? Itmd i70l g/ hvnr/d)sz y3l13jq should be placed

A. vertically.

B. horizontally and in a direction parallel to the wave's direction of motion.

C. horizontally and in a direction perpendicular to the wave's direction of motion.

D. none of the given answers

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Electromagnetic waves ar z1tyv q5u,j*ge

A. longitudinal.

B. transverse.

C. both longitudinal and transverse.

D. neither longitudinal or transverse.

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not electromagnetic in natur.jx/:v+z tgxl)d2sz axn +q p/e?

A. microwaves

B. gamma rays

C. sound waves

D. radio waves

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Visible light ranges inagl*ye;8q z8p1yrpc * ngf t/bh,ir 70 wavelength from

A. 400 mm to 750 mm.

B. 400 nm to 750 nm.

C. 500 mm to 850 mm.

D. 500 nm to 850 nm.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The energy an electromagnetic wave transports per unit time per unit area is th(e9nsrl.wxw (py9v q*l0e9 hbey9b xqe pw9.hw9l*s nl(ve0r(

A. energy density.

B. power.

C. intensity.

D. radiation pressure.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The force per unit area exertes7 aer9y trr-mh07 wu.d by an electromagnetic wave is called the

A. energy density.

B. power.

C. intensity.

D. radiation pressure.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Which of the following correctly lists electrox9qyep0 xho7h+qdgmc 5e i.35magnetic waves in order from longest to shortest wave5o9pdh5hx3e07 .m+ qyq cgx ielength?

A. gamma rays, ultraviolet, infrared, microwaves

B. microwaves, ultraviolet, visible light, gamma rays

C. radio waves, infrared, gamma rays, ultraviolet

D. television, infrared, visible light, X-rays

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the electric field in an EM wave has a peak value of 2.0 V/m, what isru)z6 ; sfui9v /z3eq,y.atet the peak value of the magnetic fzie qtasr3,);v9tuyuze / .6 field?

A. $6.7 \; nT$

B. $2.0 \; T$

C. $3.0 \times 10^{8} \; T$

D. none of the given answers

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the wavelength of vyax3b6ovu3a4f+ecm l )oyn a*29, wolight waves if their frequency is $5.0 \times 10^{14} \; Hz$?

A. $0.60 \; m$

B. $6.0 \; mm$

C. $0.060 \; mm$

D. $0.60 \; mm$

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the wavelength of a 92.9-MHz radio waf9 .3eil jbozp8 t,9lvve?

A. $32 \; mm$

B. $32 \; cm$

C. $3.2 \; m$

D. $32 \; m$

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the wavelength of a radio wave sigjxe no pp6578vnal transmitted at a frequency of 7.2 MH j57 vp86pnoxez?

A. $42 \; m$

B. $4.2 \; m$

C. $29 \; m$

D. $0.024 \; m$

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the wavelength for the carrier wave in the station WBRN fp qiv xt 4d -0ov7;grb9)uz.y1460?

A. $2.05 \; m$

B. $20.5 \; m$

C. $205 \; m$

D. $2.05 \; km$

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22#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the frequency of 20 mm mi3;abbxmgn k: 4crowaves?

A. $100 \; MHz$

B. $400 \; MHz$

C. $15 \; GHz$

D. $73 \; GHz$

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How far does light travel in +(.xk u xq:dprbs3 gx yyz81z51.0 ms?

A. $3.0 \times 10^{14} \; m$

B. $0.30 \; km$

C. $3.0 \; m$

D. $30 \; cm$

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How long does it take li-/b0hzr hm 6 cdaej--fght to travel 1.0 m?

A. $3.3 \; ns$

B. $3.3 \; ms$

C. $3.3 \; ms$

D. $3.3 \; s$

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How long does it take the signal from a local radio statedm c3qk)+*y xion to travel 20 miles?

A. $2.8 \; s$

B. $108 \; ms$

C. $38 \; ms$

D. $108 \; ms$

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How far is a light year (the distance light travels in a year)6ug(b)4 zl0jfnu y8dk ?

A. $186,000 \; m$

B. $3.0 \times 10^{8} \; m$

C. $8.7 \times 10^{13} \; m$

D. $9.5 \times 10^{15} \; m$

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A radar receiver indi0+a/)g 7n sx krjal.b:: qxhixcates that a transmitted pulse return as an echo in 20 ms after transmission.s i g+xb) :.0xq:rn /kajha7lx How far away is the reflecting object?

A. $1.5 \; km$

B. $3.0 \; km$

C. $6.0 \; km$

D. $9.0 \; km$

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Radiation from the Sun reaches the Earth (above the az* c tmf2 zlcp;(p c/xdc)21xztmosphere) at a rate of abouz2/lxcd) mc(c zx2t;pz cfp 1*t $1350 \; W/m^{2}$. Assume that this is a single EM wave and calculate the maximum value of the electric field.

A. 0.71 kV/m

B. 1.0 kV/m

C. 1.4 kV/m

D. 2.0 kV/m

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Radiation from the Sun reaches the Earth (above the atmosphere) ah:zy+fd u-ry.)tu4 7c2moide t a rate of about4+fdocrdzy:u.y-7mu e i)h2t $1350 \; W/m^{2}$. Assume that this is a single EM wave and calculate the maximum value of the magnetic field.

A. $6.7 \; mT$

B. $4.8 \; mT$

C. $3.4 \; mT$

D. $2.4 \; mT$

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the maximum value of the electric field9+wz, 0miyaqz at a distance 2.5 m from a 100-W light0i,yw+a q9 zzm bulb?

A. 22 V/m

B. 31 V/m

C. 44 V/m

D. 62 V/m

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the maximum vard-da6w,qzou b *r):o8nuu2alue of the magnetic field at a distance 2.5 m from a 100-W ligoudna,qb)6zd *2 -urou:rw 8aht bulb?

A. $0.20 \; mT$

B. $0.14 \; mT$

C. $0.10 \; mT$

D. $0.071 \; mT$

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32#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-mW laser puts out a narrow beam 2.00 mm vs /-w.qe o,wjin diameter. What is the average (rms) value of te/o,-wwv .sjq he electric field?

A. 0.95 kV/m

B. 1.3 kV/m

C. 1.9 kV/m

D. 2.7 kV/m

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33#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-mW laser puts out a narrow beam 2.00 mm in diameter. 3u 3fm0c owxrnf):rl( What is the average our 0 )cl3nxfw(mr f:3(rms) value of the magnetic field?

A. $4.5 \; mT$

B. $6.4 \; mT$

C. $9.0 \; mT$

D. none of the given answers

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How much energy is transported acrojb4m m.m+e(ctp)kt3e 7n u op-ss a $1.00 \; cm^{2}$ area per hour by an EM wave whose electric field has an rms strength of 21.5 V/m?

A. $0.44 \; nJ$

B. $0.44 \; mJ$

C. $0.44 \; mJ$

D. $0.44 \; J$

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Estimate the average power output of the Sun, 8/dx-gg,* jjm k4xvddbl-pr9 given that about $1350 \; W/m^{2}$ reaches the upper atmosphere of the Earth. The distance from the Sun to the Earth is $1.5 \times 10^{11} \; m$.

A. $1 \times 10^{26} \; W$

B. $2 \times 10^{26} \; W$

C. $3 \times 10^{26} \; W$

D. $4 \times 10^{26} \; W$

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总分:35分及格:21分时间:不限时

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