Physics Unit32: Elementary Particles

1#

What happens to the cyclotron frequency of a char ltptr7i9*c2x+; f +eqzxv r;rged particle if its speed doubleqr+p rlr ectx9+v7z ift2; x;*s? (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 particm4i g. :. zf5b2asfuxrle if the radius of it bx .g.:mu fr54iaf2szs path 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 sh-+gh8(k07mzcsbb d kghy/8 kyows two electrons approaching each other, interacting, and then leaving each other. What particle is being exchanged during the interac 8 mcb( ghh +yyk/87sbd-gkz0ktion?

(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 jti sx5zs9 80oweak interaction 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 charged electron iscd;s w,nl(7h z (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 in the mass of the virtual exchange par ysjvujie 6i,+ 3bt*b)ticle have on bj *+ti)sieu,3j6yv bthe range of 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 for the weak force isql 9g8xf9u 4uap*:oel 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 the weak force are very massive (about 100 times as 2 f 3ok(jxk (c46eewrimassive as a proton). This would lead o(c2kix(6fe 3kw jeo r4ne to expect 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 quarks is calemde/3k v) -nam4 a4is-hlxh)led (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 lighhemc-u +x29ib,urwe 3 t (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 not create an odram8f b:, yj.wlz)ut*d number of electrons and positrons is that sl by)f jw,ra8*.utmz:uch a process 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 permisskzsb s9,b-xt heoh6 w75ny84r ible? $\Sigma^+ \rightarrow \Lambda^{\circ} \;+\; \pi^+$ (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 allowe06aozxo :n7 urd? $\Sigma^+ \rightarrow p \;+\; \pi^+$ (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? oo2e x1 9lzp9)ffum)e$\pi^{\circ} \rightarrow \mu^+ \;+\; \nu_{\mu}$ (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 exampl d*i:tguemx0: e 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 exampma1w3l n*zu kf4 l/7 qo5/(qi.wsnqfmle of (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 exam17ljmsa1ys buy81cv6 t y8;c mple of (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 example8g 1 kt:l d*dujgxrpm1 92)xts of (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;x zmel24fy4a but do interact via the weak nuclear force (and presumably by the much weaker graxya z f;44elm2vitation 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 callewd*esta kn+w-o 4n(qsq :34 dkd (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 come (n)gwp9 h*skej ;k9cposition of a $\Lambda^{\circ}$? (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 u17cjusp ht2:they (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 quarjh . qno5.*citks and antiquarks 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 quam9pjg* e9 ,zjrrk 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 of quarksg*jycha) p8h 1prw8 8e 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 considered to bb spw(1 i/wlajrd9 ;;d4y w8bce one of the four fundamental forcess 9jc 4yl(bd8 /ww;wai 1dp;br? (1.0 分)

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29#

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A significant step in "unifying" the forces of nature was the discoveryz1d3klk3 ou zmrdv-+ - that two of the so-called fundamental forces were two parts of a single force. The two forces that were lv z+kz 3rd-ku1-o3md 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 (Gmqx)h( usss su4 :gtk5 mis4+6UT) is a sought-after model that would unify three of tu(g5 ms 4: kqut)+xssh4m sis6he four forces of nature. Which force 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.en+.b(rpli2l 4 GeV electrons? (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 to accelerate pronf+p p0ejhr 12-wd5ji+ mu9lu tonj+lf 5iu0-dup+p219 hmwn erjs? (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 acztnu)x j6 q**ocelerates protons in a 1.7-T magnetic field. What is the frequency for the applied n*q*xtu j6 )ozalternating 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 radius 0.25 m ac6p4u+vr+j+w4j ojs csl) 9rxdd33 yzpcelerates protons in a 1.7-T magnetic field. What is the kinetic energy of p)u+r w4sv++zds j3cxoj46yjp r9dl 3 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 charge as a proton but approximately twice qnvlyvaw9ylg5 u1 owp(* 2 nx2le 2f)4the proton mass. Suppose deuterons are being accelerated in a2ly9l nu nxv (2owp w)4qyal52 1eg*fv cyclotron in an orbit of radius 75 cm at a frequency of 8.0 Mhz. What magnetic field is needed? (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 pz: 2: inhr+*il npa)1b r4hz:flnzyf :roton-antiproton pair by annihilation of a very high energy photon. The proton and the anti-proton have the same masses, but opposite charges. W2i+)l :bhnlrzzy n::r4 fn 1:pihf*azhat 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 + positron) decays, it emits two phos x(( .svycdd:o*rro.8fvd g*tons. What are the energies osdox r(.csyfd*8v o* (:.dr vgf 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 electrl(zpjp w nnm -+ tqo6nrp0;n.0on. What is the range of the force me +;zn -npwr(op0nnl.0 6jptqmdiated by this 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 protaw;4 xgeicf:qaf 1s:n; a1 ;vg8ubgk+ on as the virtual exchange particlefx1q akcg8s: ;iggfea +1wb;u; a nv4:. (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 reacti i6 azptjurnn8uq)+59 on.
$\pi^- \;+\; p \rightarrow \pi^- \;+\; \pi^- \;+\; \pi^+ \;+\; \;\;\;\;\;\;$ ? (1.0 分)

A. $p$

B. $n$

C. $e$

D. $\nu_{\mu}$

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41#

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Identify the missing particle in the following rei fyr/er4wh963i lhteeo,)0 iaction. $\pi^+ \rightarrow \mu^+ \;+\; \;\;\;\;\;\;$ ? (1.0 分)

A. $p$

B. $n$

C. $e$

D. $\nu_{\mu}$

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42#

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Identify the missing particle in the follow0b1kcm*kzgtd nh.) *hing 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 yww3-xumn(-t:m ,bd t($^2 H$) is (1.0 分)

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