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Unformatted text preview: L First Letter Last Name Physics 102 04W Midterm 1 Time 50 minutes Student’s Name: Student Number:
This exam consists of 5 pages plus a formula sheet. Special Instructions 1. Simple scientific calculator — no graphing calculators
2.} Use the backs of the pages for rough work 3. Clearly show all your work 4. Use pen, papers written in pencil will not be accepted for regrading 04W NF“ 1 Question 1 (5 marks)
Consider the following two reactions, where a proton or a neutron is removed from a nucleus of sodium — 23
a) ﬁNa + energyenge + proton 3
b) lea + energy—ﬁNa + neutron Given the following masses:
Atomic Masses: Na—23, 22.989770u : Ne22, 21.991386u : Na22, 21.994437u me = 0.000549u; mp = 1.007276u; mgHm = 1.007825; m” =1.008665u Determine the energy (MeV) required to remove:
i) a proton ﬁst—M FLA) ii) a neutron \a‘U‘l no} iii) Is the proton or neutron more tightly bound in the sodium23 nucleus? Explain! Question 2 (4 marks)
A radioactive sample of sodium24 (half—life 15 hours) is mixed into a closed water system. The sample’s initial activity is 1.6x104 Bq. i) How many sodium24 nuclei are in the sample? [‘ XKOR ii) What should be the sample activity 30 hours later? OHOMLS’ {3V iii) After 30 hours a 100 m1 sample of water is taken from the water system and its
activity is 2.0 Bq, what isthe volume of the water system? QOXUDH my 04w MT] ' 7. Question 3 a (2 marks)
A certain nucleus after absorbing a neutron emits a [3‘ and then splits into two alpha particles. The A, Z of the original nucleus must have been: i) 6, 2 ii) 6, 3 iii) 7, 2 iv) 7, 3 V) 8, 4 ®
Question 3 b (3 marks)
The figure shows two separate metal spheres. Each sphere has the same positive charge, q.
Points 1 and 4 are the same radial distance from the centre of their respective sphere, so are
points 2 and 5 and also points 3 and 6. Rank the points 16 according to their potential, greatest
ﬁrst, with the potential taken to be zero at an infinite distance away from the spheres. Greatest Smallest V i 7 V'L 04W MTl ’% Question 4 (5 marks) The diagram shows a region of space where
there is a uniform electric field of 40 i N/C.
The grid has a scale of 1.0 m per box and
the electric potential at the origin is +40 V.
You are asked to identify the points (A, B,
C, D or E) where different quantities are the
greatest or least. If the quantity is the
same at all points then clearly state this. 3'
9"? i) Electric Potential Reason: ii) Electric Field
Greatest ‘ Least Reason: iii) Electric Potential Energy of a negative charge Greatest Q Least 1 3 42\ Q 36”!“
iv) If akégﬁive ghahggis released at A, will it move towards B or D? Explain! v) When it reaches B or D, what is its‘kinetic energy? 04w MN 4 Question 5 (6 marks) i) For each of the following diagrams draw an arrow indicating the direction of the net electric field (due to the point charges) at each of the positions indicated by the dots.
If the net field is zero then label it as E = 0. All point charges have the same magnitude. ,0 ' @————»—© it;
a 4K? a'_i‘?i_..__f°[email protected] ® _________ G a) ' b) ii) For ﬁgure b) if the magnitude of each charge is q and the length of the edge of the square is 1.0 m. Calculate the net electric field at point P.
l 4Jt80 Report your answer in unit vector form and in terms of q and k = 04w Mn 5 c = 3.00 ><108 m/s NA : 6.02 x 1023mole'1
[6] = 1.602 ><10‘19 C
me = 000054858 u mp = 1.007276 u mn = 1.008665 11 1 u : 1.661 ><10‘27 kg
1 u = 931.5 MeV/c2 E=(Am)c2
%’¥=——/\N T1/2: 11:3
NZN06A1
16:71:32?“
quE
E=4mor212
<I>E=fEdA
VB—VA=— fEdl=V—quﬂ
AV:Ed : q 41rcor Q=CV
C_&o.é .7 = 71qu
R = pi p = p011 + 01(T  To)1
P = Bi? a  b = (szX + ayby + azbz = abcosﬂ a x b = (czbe — azby)'i + ((2sz — axbz)j + (ax?)y — aybx) la la >< bl = absinﬁ g=9.8m/s2
vzvo—i—at ac : xo+vot+%at2
v22v3+2a($—$0) k =1/(47r60)= 8.99 ><109 N ~1112/C2
co = 8.85 x 10‘12 F/m or CQ/(NmQ)
pg 2 47r X 10"7 H/m or Tm/A quva
F=il><B
u=iAN
T=p><B
IB(7")=%‘:—i
F=poglﬁl
B=poni
ngfB‘dA
£_.—N9(%B
N<I>B=Li
L=Iuon21A
82—0de 1: %(1—€_Rt/L)
UB=§Li2 MFR; fBdA=0
fEdl=—d%(fBdA) f B ’ : #Oiencl + [1060??? ...
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 Fall '02
 AXEN
 Physics, Electric Potential, Electric charge

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