11
Typical cross-section for low energy electron
atom scattering is ----cm2
(a) 10-16* (b) 10-24 (c) 10-32 (d)
10-140
12. A beam of
negative muon can be stopped in matter because muon may be-----
(a)transferred into an
electron by emitting a photon
(b) obstructed
by a proton, which goes into an excited state
(c) captured by an atom into a bound orbit about the
nucleus*
(d) none of these
13. In Fermi
Golden rule transition probability depends on----
(a) only density of final state (b) only probability amplitude
(c) both a and b* (d) density of initial and final states
14. Two
radioactive materials X1 and X2 have decay constants 10λ and λ respectively. If initially
they have the same number of nuclei, then the ratio of the number of nuclei of
X1 and X2 will be 1/e after a time-----
(a)
1/(9λ)* (b)
1/(10λ) (c)
1/(11λ) (d)
11/(10λ)
Hint:
N=N0e -λt ; N1/N2 = N0e -10λ.t/
N0e –λ..t; 1/e=e-9λt
15. The
nucleus of atoms 4 Be9 contains--- up quarks and --- down
quarks
(a)
13,13 (b) 13,14* (c)
14,13 (d)
14,14
16. Suppose
that a neutron at rest in free space decays into a proton and an electron. Tis
process would violate---
(a) conservation
of charge (b)
) conservation
of energy
(c) ) conservation
of linear momentum (d) conservation of angular momentum*
17. Lyman
transition involves----
(a)
largest change in energy (b)
smallest change in energy
(c)largest change in PE (d)
smallest change in PE
18. A crystal
belongs to fcc lattice with four atoms in unit cell, the structure factor for
(010), (200) reflections are----
(a) 2f
and zero (b) zero and
4f* (c)
2f and 2f (d) zero
and zero
19. A unit
cell has the dimensions a=b=4A0, c=8A0, α= β=900,
γ=1200. The spacing between (210) planes is ---
(a) 1.54A0 (b)
1.313A0* (c)2.14A0 (d) 0.94A0
20. Using
Newton’s forward interpolation formula the value of f(1.6) is----. Give that
(x,y)=(1,3.49), (1.4, 4.82), (1.8, 5.96), (2.2, 6.5)
(a) 5.54* (b) 4.45
(c) 5.35 (d) 6.4
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