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

The strength of both the elecruawx+i5ow-.*dybxspf z (8 2tric and magnetic fields in the radiation field are fouxfi+8pw* o-u(2 ra .dyxsw5b znd to decrease with distance 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 traveli:6eteb63y*0k ti+d3nd eemp2b.ah 9 cb qqm-png to the east. At one instant at a given point it mb:a2qd ph6ee en.3b69bmt3q+dptk c-ye*0i s $E$ 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 radiated1bl. :3im raio c4ofd0 by a straight wire antenna that is oriented vertically. Whc:4i bda 0r1l.o3fimoat should be the orientation of a straight wire receiving antenna? It 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 wavei+/8eav24t b0z.inlw i r 7rdos are

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 nas;k -fq; /+mhlcaaxp:ture?

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 in wavelength frs4jxt:eup j26i8dyxd. u(j:lr, lt(kom

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 h*l5 f5mvqzmz78c :ekper unit time per unit area is thel7 v :mqezf5 khm*8c5z

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 exerted by an electrombwfjv,6 5r2in agnetic 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 lio: /txsr z:yv3beo3(dc4, ik dsts electromagnetic waves in order from longest to od d :3ri4e(tbvy: xks,3/oczshortest wavelength?

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 is tb7dzfx9/8 vrksg+ mw;he peak value of the magz / 8x9krbmsfgv;7+wdnetic 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 light waves if their fray8pg(m 7jk b/equency 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 wave/e8oyyf0m zw+?

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 signal,+.li idag) *ezvszj:75 kzlq transmitted at a frequency of 7.2 ) *a:j5.+zki l,s gvqz le7idzMHz?

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 WBRtq/4m c1ymnw 7N 1460?

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 ofk d5y.d 6vai4p 20 mm microwaves?

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 1.0 ms8k,j, mf )wujk?

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 light5:jz s-s bjd4h 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 station to travel 20 mileg)n yt/ fo1)gl14 fmigs?

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 y:au5 9onkuu 1 wzk4/5dbt4sp hear)?

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 indicates that a transmee/v6 paj2; + 5xtddmditted pulse return as an echo in 20 ms after trd ev 5/+xe6a jp;mdd2tansmission. 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 atmosphere) at a rquj6b o yh;i2bve;8 s7ate of about ;86bib u;y2q7ehojs v$1350 \; W/m^{2}$. 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 atmo2idozna76a 9bsphere) at a rate of about 97b zn6ad2ai o$1350 \; W/m^{2}$. 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 field at a distance 2.5 m b/ eg; dz,ghq. kpd0b4from a 100-W light bulbhpq.z e4/ gbdb0k; ,dg?

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 value of the magnetic field at a nzr7r u70uv:i+fu+je distance 2.5 m from a 100-W lig+ruz +venjfir7u 07: uht 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 in diameter. What i4,r3 ed,e l z sx*0rx4bbbtme1s the average (rx x*4t4, m1b0,lzbeeerbd 3srms) value of the 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. What is zetb1mq3.+t un:qm,u -kh t(w the average (rms) value of the magnetic fiel tq+u(t-um kn ,:qw zemb.13thd?

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:(*arayb oob 4 across 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 ocq9(ss/y .vv- 6zyhykf the Sun, 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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