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

The strength of both the electric ay6u( b7 v(ooh3qpt/j3dhy+ae 3 eb g8snd magnetic fields in the radiation field are found to decrease witvsyuhh3y/e((6 +g 3qjeod3t7b p o8bah 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 traveling to the east. At one instant at ad r t*z o19+z 9j5wocs vy)+./mcvmcci given point itmm cz1c.i+s/v9ot *j+ vzyorc )9w5dc 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 radiated by a straight wire antenna that is o(fda8 ipecs3)riented dsac (3)iefp8vertically. What 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 wavesa)j*rip+2;o.hl qtgs y 2+ynd 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 nh/h;t rllz:,(rlaot 4ot electromagnetic in nature?

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 fromkfdpyp 7w* h 1o.,tcd/

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 u0g3v(b:sslag;q3xu transports per unit time per unit area is the0 au(l:qb su;xv 3gs3g

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 electromagnetic eb 0kvh+qe v vmxp(6 fi60;n c3k1s8rpwave 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 electromagnetic waves in order from lon*an+ttz9m pnrdv *g. 8gest to shortest wgmt*n .*v nap r8+tzd9avelength?

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 28jj-d gesek y50,zr7z02qimw.0 V/m, what is the peak value of z-2jisk87y gw q0 ,dejr50zem the magnetic 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 frequenc y6k w/ nhk,teio04/hpgg5y;sy 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 e:sr z/0m iw(cw2kx75 4vv xbm92.9-MHz radio wave?

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 transmitted at a frequen up v *tk9xtn,)kvse;-cy of 7.2 M,nxkuk-s* ) 9v ;etvtpHz?

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 s l*yq77 tl8ku*r/oe aqtation WBRN 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 of 20 m*z :kqslx9 zdkbs z/mu/5:f0am 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.m(nq vguo -dsuv4j4,g: 2cr9b 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 ojsmz6aueu8x927z y n9md(7yght 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 mir4 mj8bxkfh;7les?

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 distanceyx8k ss,)kx -8 rocd;w light travels in a year)?

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 thagwt:b *) p8lr.w iajb1t a transmitted pulse return as an echo in 20 ms after transmission. How far away is the ref*j:bl wtpg .br8)1iawlecting 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 (ab1 z4j(x zjvdr0ove the atmosphere) at a rate of abo jzj4(10rzvd xut $1350 \; W/m^{2}$. 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 tp::i1cuwa: kahe atmosphere) at a rate of abop k::wa u:1aciut $1350 \; W/m^{2}$. 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 distanc+nuo(mo :b9 sie 2.5 m from a 100-W lign o(os+9u:bi mht 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 value 1ap 0 +agmyi*yof the magnetic field at a distance 2.5 m from a 100-W lighi ya0ymg a*+p1t 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/ ds2 tlo5.g*hlrhyyyq . 1wstrjj815.00 mm in diameter. What is the average (rms) value 5hyl2g t1s.hd jj q5 y/sw8y.ot*lrr1of 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 the ;f/)y- g sm d5vtz7csgaverage (rms) value of the magnetic-)sd7;zgm 5vt f gycs/ 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 transx ;/mq,8s 4z*dmxlyv mported 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 o6, tzbhwj y0y:q.b -vautput of 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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