Physics Unit32: Elementary Particles

1#

What happens to the cyclotron frequency of a charged1e(h ga ybt.,b particle if its speed doublesbtg,e. b (hy1a? (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 freqtdx19mn xy09p*az ;fbuency of a charged particle if the radius of its path doubl nfbzpy* d909mx1a ;txes? (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 approaching each other, interaczb2cju oe9bol12v0zc, ivxywo2 1 ,8e1lpe;vting, and then leaving each other. What particle is being exchanged during the interactii2e9lc1w zeouvo ;201l p1jey2,bcvxzv b o,8on?

(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 interaction k( a5 cerpp(v2of 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 ele; gv9ka;m5 xzmpal-v *ctron 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 in the mass of the virtual exchange partq(.8v5pejcju ,yrb- 4 suez8p icle have on the range of the forczj 4r,y(u.q5v- j 88cebpupsee 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 is (q2u.n g;yxmilk ox** t2w-do 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 fov7dcg8 pw;h r4rce are very massive (about 100 times as ma 47pdgrwc8hv; ssive as a proton). This would lead one 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 callnc7(z 6smjdu 5-tz r(zed (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 travelsf 8q)u hyt.jr0se5f b; at the speed of light (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 odd number of electrons and positrons iba:. uow,a9tp uvk 4b8s that sucho aub k8bw:9t4 au,v.p 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 per.un;8 *g sore0(b ncxtmissible? $\Sigma^+ \rightarrow \Lambda^{\circ} \;+\; \pi^+$ (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 allow 44ua-u 0xepgaed? $\Sigma^+ \rightarrow p \;+\; \pi^+$ (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 allowe lqu; r9nqq e3xc7xq-k-lct20 d? $\pi^{\circ} \rightarrow \mu^+ \;+\; \nu_{\mu}$ (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 example o h g k*qq):9vyokrm88*z,aua wf (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 examplmxuq ,h79m9mq e 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 exampl+ ggr z)k;ja(0(8ro:nd cdwxe e 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 example orszrhg p jxf,f0*64(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 interact via the wea,qq)u45ik umt:un t2xj e1x57 bt,3vr 8lesw bk nuclear force (and presumably by the much wea ls478uix vet3u) 5 r 2u1mtej ,5tx:knw,qbqbker 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 st+j+mb2a70 z9quw3km 9frark *mut5 hubgroups called (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 compositionlk0go2oz cbu*o+k z9jqu4u +. 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 featurpb5un 3 yc9ee1e of quarks is that 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 quarks and antiquasoswz31042 sc yiic.8az z h l3j;xfl8rks 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, thep0ua - mh lx)zpw/hksqs+tjq:*,j j;9 quark 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 quul;fn/*i6by;6phn j zarks 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 be one of the four f7nkh ft(gw +4o9.d exq 4vf*:spak6 giundamental forces?t g94(ose6d.4v k7*xnaiqk: fwgh f+ p (1.0 分)

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29#

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A significant step in "unifying" the forces ( 9 .) cxh 5uh5o dv1ifiv/92go+hjoht)gvwthof nature was the discovery that two of the so-called fundamental forces were two parts of a single force. The two forces that wghvx5f))1givhu cw +h959d( jo/h2.tihv t ooere 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-aftehg7jb1d 2 4eipr model that would unify three of the four forces of nature. Which force is the one it would not iiehbd7j12g 4pnclude? (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 ana m1 ) u/wfrx4dxekhh9m6. e1 beam of 1.4 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 tc7c .605fv -ixggkyom8h)bh a o accelerate proton6ih mbk facgv o5-7 )0cgy8xh.s? (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 accelerates protons in a 1.7-T mf4 gcvhku))sg50 3vknagnetic field. What is the frequh4 kk))v3g 5 cnsv0gfuency for the applied 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 radius 0.25 m accelerates protons in a 1.7-T magnetic fo a 0gdw,x35t vfy8m+yield. What is the kinetic energy of the protons when tdo8fwavyg , t+y05x3mhey 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 char;o,t5iw . 6fpl do(htvge 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 8o5t. ;ldvh, it(o pfw6.0 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 proton-antiproton *goiuu1kj c7 ff/.d9 ,zn3-mz t:bxtmyl7d)xpair by annihilation of a very high energy photon. The proton a:lg-7ztu7fzo. m*d /nmy d931xcj),fxb kuitnd the anti-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 + positron) decays, it emits ea-( 0uhyh5sb oc/kjs uv*q) dbw 2fsog4-97utwo photons. What are the energies of the ph0u/ sa sej-kod9uv)o-5ub7g4*cf qb( h wsy2 hotons? (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 eleog-w1 2;imu/eqq 4oaoctron. What is the range of the force mediated by thiao4u iq1q2-oo we/mg ;s 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 as the vi ypqf:acn8;j xk-5nt*rtual exchange part a cjnkxy*8; 5fqt:n-picle. (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 fol)- 0atvqkdkj. lowing reaction.
$\pi^- \;+\; p \rightarrow \pi^- \;+\; \pi^- \;+\; \pi^+ \;+\; \;\;\;\;\;\;$ ? (1.0 分)

A. $p$

B. $n$

C. $e$

D. $\nu_{\mu}$

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41#

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Identify the missing particsd4e8:8hia ,jzjjl lxna*8g-m8h ka:le 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 / a/ldn5w8o tz8mkkdz*.yei 2 t9le*uin the following reaction. $\pi^+ \;+\; \Lambda^{\circ} \rightarrow \Sigma^+ \;+\; \;\;\;\;\;\;$ ? (1.0 分)

A. $p$

B. $n$

C. $\pi^{\circ}$

D. $\nu_{\mu}$

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43#

单选题搜藏此题

The number of quarks in a deuterons:8:ncb+mc r n ($^2 H$) is (1.0 分)

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