Physics Unit32: Elementary Particles

1#

What happens to the cyclotron frequency of a charged particlj.qdshzlzcyboy+b d +t0 76-; e if its speed doubles6z-tyhobq+d7 ybdjzs ; lc0+.? (1.0 分)

A. It triples.

B. It doubles.

C. It halves.

D. It does not change.

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2#

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What happens to the cyclotron frequency of a charged particle if the radius of0g+b2idegb7/j /mt hs its pg0bs+/t2e h/idj g7bm ath doubles? (1.0 分)

A. It triples.

B. It doubles.

C. It halves.

D. It does not change.

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3#

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The Feynman diagram shows two electrons approac h(ch*3bno hy6hing each other, interacting, and then leaving each other. What particle is being exchanged duriyo*n 3(hbhch6 ng the interaction?

(1.0 分)

A. pion

B. virtual photon

C. neutrino

D. $W$ particle

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4#

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The Feynman diagram shows the weak i 7(ufv g+tn;vsnteraction of a neutrino ($\nu$) and a neutron ($n$), mediated by a $W+$ particle. The interaction produces an electron ($e-$) and another particle. What is the other particle?

(1.0 分)

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5#

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A positively chargedmfyg*j)+2 o(i,e w inoomm+-uw72jbt electron is (1.0 分)

A. called a proton.

B. called a positron.

C. also called an electron.

D. not found in nature.

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6#

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What effect does an increase inaa0kkxi/ku +ya5 (42; -on7m wvbrypo the mass of the virtual exchange particle have on the range ofx ua/ m;k( 0o5+4-akyywnob7r akiv2p the force it mediates? (1.0 分)

A. decreases it

B. increases it

C. has no appreciable effect

D. decreases charged particle interactions and increases neutral particle interactions

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7#

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An exchange particle +dyyhl31ou fecz49 c3 for the weak force is the (1.0 分)

A. photon

B. meson

C. W particle

D. graviton

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8#

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The exchange particles for t8 td)vqp: b+rhhe weak force are very massive (about 100 times as massive as a proton). This would lead one to exqdr)b t8vp:+ hpect that the weak force would (1.0 分)

A. act over a very long range.

B. act over a very short range.

C. only act on very massive particles.

D. be transmitted at the speed of light.

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9#

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The exchange particle for h6 p x0hqetcmkyvs7 .;-f7rk5quarks is called (1.0 分)

A. the stickon.

B. the gluon.

C. the epoxyon.

D. the epsilon.

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10#

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A particle that travels at the speed of lig nd.1s58t) +b+jdsszu 9k ktivht (1.0 分)

A. has never been observed.

B. must have zero rest mass.

C. must have a very large rest mass.

D. has infinite energy.

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11#

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One reason a photon could *fos wvqq lzv6rxn: 4 8.*u;npnot create an odd number of electrons and positrons is that such a proclpqvuw f *v:xz;rn4n s6*o. 8qess would (1.0 分)

A. not conserve charge.

B. not conserve energy.

C. require photon energies that are not attainable.

D. result in the creation of mass.

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12#

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Is the following decay permissrxj ;zfo *cjr0mr-m2m b0 ))yumxi4 +su7d1 cqible? $\Sigma^+ \rightarrow \Lambda^{\circ} \;+\; \pi^+$ (1.0 分)

A. yes

B. No, because charge is not conserved.

C. No, because mass is created.

D. No, because lepton number is not conserved.

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13#

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Is the following decay allod)b:wf o:w(fi wed? $\Sigma^+ \rightarrow p \;+\; \pi^+$ (1.0 分)

A. yes

B. No, because charge is not conserved.

C. No, because mass is created.

D. No, because lepton number is not conserved.

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14#

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Is the following decay allowed?,.yn 2ft lywp71ly.gh $\pi^{\circ} \rightarrow \mu^+ \;+\; \nu_{\mu}$ (1.0 分)

A. yes

B. No, because charge is not conserved.

C. No, because mass is created.

D. No, because lepton number is not conserved.

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15#

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The neutrino has (1.0 分)

A. enormous rest mass, positive charge, and spin quantum number 1/2.

B. negligible rest mass, negative charge, and spin quantum number 1.

C. negligible rest mass, no charge, and spin quantum number 1/2.

D. none of the given answers

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16#

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An electron is an exbm5+ myxn-k8 hample of (1.0 分)

A. a lepton.

B. a meson.

C. a baryon.

D. a gauge boson.

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17#

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A proton is an example ofouu-zc q kr7pom*:,ef,wk-k t 1q;/g b (1.0 分)

A. a lepton.

B. a meson.

C. a baryon.

D. a gauge boson.

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18#

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A neutron is an example of 7y-8/ 03:kk le a3dbi:wziwhggzvog2 (1.0 分)

A. a lepton.

B. a meson.

C. a baryon.

D. a gauge boson.

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19#

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A photon is an example oo*i2omb 8 ;mnvd.i*i,c yso+hf (1.0 分)

A. a lepton.

B. a meson.

C. a baryon.

D. a gauge boson.

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20#

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Particles that do not interact via the strong force but do in1(amk +ms.xl 0 t(yoewteract via the weak nuclear force (and presumably by the much weakerkylw1tme(aox( +.m 0s gravitation force) are called (1.0 分)

A. gauge bosons.

B. leptons.

C. baryons.

D. mesons.

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21#

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Hadrons are divided into two subgroups called 9wo/,cr7qrv lphq;*: hn*2) azjtromhdo2 4y (1.0 分)

A. baryons and leptons.

B. leptons and mesons.

C. mesons and baryons.

D. nucleons and gauge bosons.

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22#

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A quark is (1.0 分)

A. a constituent of a nucleon.

B. a constituent of a hadron.

C. an elementary particle.

D. all of the given answers

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23#

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What is the quark composition of a .z i9.pvvi 60dpxez5a $\Lambda^{\circ}$? (1.0 分)

A. uud

B. uus

C. uds

D. uss

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24#

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A distinctive feature of quarks is that th2l n07m1p0c1u lq k kw;ms0yvqey (1.0 分)

A. have zero rest mass.

B. have zero charge.

C. have fractional electric charge.

D. are always observed singly, since they do not readily interact with other particles.

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25#

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The charge of some quarks and antis38 (fvn2cy h4 soy1ijquarks is (1.0 分)

A. e/4.

B. e/3.

C. e/2.

D. e.

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26#

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When a quark emits or absorbs a gluon, the qu (4yqw-x4q /-b,o zbdtbp ypb7.yec)qark changes (1.0 分)

A. its charge.

B. its mass.

C. its color.

D. into an antiquark.

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27#

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The number of types e nu2)qsfh62 pof quarks is (1.0 分)

A. 2.

B. 3.

C. 6.

D. 8.

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28#

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Which of the following is not consrwo;vj3 077rosv dn. qidered to be one of the four fundamental forces?3orrsvq0dv.no; w7 7 j (1.0 分)

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29#

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A significant step in "unifying" thewryg.y58 ub+2oo 8uen1i ht q8 forces of nature was the discovery that two of the so-called fundamental forces were two parts of a single force. 8e. wh5y8+8q 2rgno1 youiutb The two forces that were so unified were (1.0 分)

A. the electromagnetic force and the weak force.

B. the electromagnetic force and the strong nuclear force.

C. the electromagnetic force and the gravity force.

D. the weak force and the strong nuclear force.

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30#

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The grand unified theory (GUT) is a sought- dic;ps( dce1ks 5c1lc8nj5k9 after model that would unify three of the four forces of nature. Which forl 1dc5cp k(1k9sejic5 cns; 8dce is the one it would not include? (1.0 分)

A. gravitational

B. strong

C. weak

D. electromagnetic

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31#

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What is the wavelength for a beam of 1.4 GeV electrond lb(;8dxfpb+ .heit e2,c9xcs? (1.0 分)

A. $8.8 \times 10^{-14} \; m$

B. $8.8 \times 10^{-15} \; m$

C. $8.8 \times 10^{-16} \; m$

D. $8.8 \times 10^{-17} \; m$

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32#

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A cyclotron operates at 10 MHz. What magnetic field is needed d;3me.:va tr;vpru53nuc z ;y to accelerate protou enzcdav 5t3rypr;3m v.u:;; ns? (1.0 分)

A. $0.12 \; T$

B. $0.25 \; T$

C. $0.66 \; T$

D. $1.5 \; T$

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33#

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A cyclotron of radius 0.25 m accelercffvq cu276fl:(va6gates protons in a 1.7-T magnetic field. What is the frequency for the ap 2uagff(vqc 6l 7f6c:vplied alternating voltage? (1.0 分)

A. $0.26 \; MHz$

B. $2.6 \; MHz$

C. $26 \; MHz$

D. $260 \; MHz$

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34#

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A cyclotron of radiu (p t f +m-2uftu:9v8v;egkike0 wt7szs 0.25 m accelerates protons in a 1.7-T magnetic field. What is the kinetic energy 9k+pw zfuek20stuit:fvv87 -e (;mtgof the protons when they leave the cyclotron? (1.0 分)

A. $7.8 \; keV$

B. $8.7 \; keV$

C. $7.8 \; MeV$

D. $8.7 \; MeV$

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35#

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A deuteron has the same charge9v9b9ivpuh 5d as a proton but approximately twice the proton mass. Suppose deuterons are being accelerated in a cyclotron in an orbit of radius 75 cm at a frequency of 8.0 Mhz. What magnetic field is neededhp9 vbduv i995? (1.0 分)

A. $0.011 \; T$

B. $0.11 \; T$

C. $1.1 \; T$

D. $11 \; T$

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36#

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Suppose you were to try to create a proton-antiproton pair dcw/owkt4s c( hhomn-a7 6x8 -by annihilation of a very high energy photon. The proton and the ann48 om6- (h/otwawshcx cd 7-kti-proton have the same masses, but opposite charges. What energy photon would be required? (1.0 分)

A. $1.022 \; MeV$

B. $1880 \; MeV$

C. $940 \; MeV$

D. $223 \; MeV$

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37#

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When a positronium atom (electron q0 u,c0gcfu1i + positron) decays, it emits two photons. What are t1u0u0 fig,qcche energies of the photons? (1.0 分)

A. 0.511 MeV and 1.022 MeV

B. 0.225 MeV and 0.285 MeV

C. 0.256 MeV and 0.256 MeV

D. 0.511 MeV and 0.511 MeV

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38#

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The pe meson has a mass of 264 times that of an electron. What is the +84uai(ghq(yow: o bdrange of the force mediated by th4g:i+ (oo d(qabw 8uyhis particle? (1.0 分)

A. $1.5 \times 10^{-10} \; m$

B. $1.5 \times 10^{-12} \; m$

C. $1.5 \times 10^{-14} \; m$

D. $1.5 \times 10^{-15} \; m$

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39#

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Calculate the range of a hypothetical force with the proton a6 g twhh1xz*2hs the virtual exchange particle6* 1 xwhzthgh2. (1.0 分)

A. $6.7 \times 10^{-25} \; m$

B. $2.1 \times 10^{-16} \; m$

C. $1.5 \times 10^{-15} \; m$

D. $6.0 \times 10^{-8} \; m$

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40#

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Identify the missing particle in the following rea3k8syw/p fle3ction.
$\pi^- \;+\; p \rightarrow \pi^- \;+\; \pi^- \;+\; \pi^+ \;+\; \;\;\;\;\;\;$ ? (1.0 分)

A. $p$

B. $n$

C. $e$

D. $\nu_{\mu}$

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41#

单选题搜藏此题

Identify the missing particlpgw y h818xrm3yzc;-ve in the following reaction. $\pi^+ \rightarrow \mu^+ \;+\; \;\;\;\;\;\;$ ? (1.0 分)

A. $p$

B. $n$

C. $e$

D. $\nu_{\mu}$

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42#

单选题搜藏此题

Identify the missing particle in the follo/r ea1)l4u1g t l9qrxhwing reaction. $\pi^+ \;+\; \Lambda^{\circ} \rightarrow \Sigma^+ \;+\; \;\;\;\;\;\;$ ? (1.0 分)

A. $p$

B. $n$

C. $\pi^{\circ}$

D. $\nu_{\mu}$

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43#

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The number of quarks in a deuteron (ux 33a-s0h0o1i az vlq$^2 H$) is (1.0 分)

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