Mathematical Physics-I Mock Papers, Exams of Mathematical Physics

Compilation of semester exam level questions in Mathematical Physics-I on following topics. LINEAR ALGEBRA COMPLEX ANALYSIS

Typology: Exams

2021/2022

Available from 05/09/2023

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Qucstion 1
The
set
of
functions
Po
=
1,
P =
I,
2 =
*;
are
orthogonal
Anothcr
sct
of
functions
that
are
also
ort
hogonal
with
nit
wcight
and
span
tlhe
same
spare
are
Fo
=
c',
F = , F
=5r-3.
a.
IVritc
the
normalizcd
forms
ofP
and
E
for
i
==
1,2.3.
1|
with
nit
weight
on
the
range
-1
< <
+I.
3
b.
Find
the
unitary
matrix
U
that
transforms
from
thc
normalized
P,
basis
to
the
nor
Imalized
E
basis.
3
C.
Find
the
nitary
matrix
V that
trans•orns
from
the
normalizcd
E,
basis
to
the
nor
malizcd
P
basis.
[1])
d.
Expand
f(r)
=
5r?
-3r
+ I
in
terns
of
the
nomnalizcd
versions
of
both
bases,
and
verify
tlhat
the
transformnation matrix U coverts
the
P-basis
cxpansion
of
f()
into its
F-basis cxpansion.
(2+2-+1]
Qucstion 2
Thc
ON
set
of
functions
(over
a
suitablc
rangc
of
z,
y,
)
given
by
B
={lo)
=
Crc-.
Jo) = Cye-r,
Jos)
= Czc-r}
spans
a
threc
}spans
a threc dimemsional voctor
space ol functions.
V.
a.
ind
the
matrix reprcscnt
ation,
M,
of
the
operator
Lr
=
-i(y
-)in
the
B;
basis.
(3)
b.
IVhat
are
the
cigenvalucs
of
M
and
the
corresponding
cigenvectors?
(2
C.
Writc
the
cxplicit
form
of
M'
which
is
thc
matrix M writton
in
a dilcrent
ON
basis,
B =
{lo)lo,)lo3)}
using
the
unitary
givcn
below
(The
matrix
elements
of
U
are
Uij
i=
(0,,
o;))
(2):
æ =
0
1//2 -i/V2
0
1/V2
i/2
d.
Calculate
the cxpcctation
valucs
of
the matrix
MM
w.rt.
lo),
o,),lo).
3|
c.
Calculatc
the
expectation
valucs
of
the
matrix
M
w.r.t.
lo),).l).
(3
(1)
Qucstion 3
A,
B.C
arc
finitc-dimensional Hormitian
matrices
such
that
C=A+B
and
A,
B)
=
0.
The
ON
cigonvectors
of
A
are
u)u2)....
u,).
a.
Writc
down
thc
mitary
transformation
to
digonalize
Cin
terms
of
u;),i=
1,2,....
n.
b.
Consider
tlhe
natrix D =
A'
-
AB
+ A
BA
+ B +
B,
cvaluatc the conmntator
|D,C1.
(3|
c.
Lct.
A and B
be
positive-dcfnite matrices
and
and
that
for
B
be
A
9o
such
that A +
Ap
= 1
with
the
same
corresponling
cige
vcctor.
All
other
cigenval1es
of
A and B arc
less
thap
1/2.
Find
the
cxpcct
ation
value
(uC)
when
)
is
a
unit-nornalizcd
vector
3
the
largcst
cigenvalue
of
A
be
Aa
pf3
pf4

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Qucstion 1 The set of functions Po = 1, P = I, 2 = *; are^ orthogonal

Anothcr sct of functions that are also

ort hogonal with nit wcight and span tlhe same spare are Fo = c', F = , F =5r-3.

a. IVritc the normalizcd forms ofP and E for i == 1,2.3. 1|

with nit weight on the range -1 < < +I.

3

b. Find the unitary matrix Uthat transforms from thc normalized P, basis to the nor Imalized E basis. 3 C. Find the nitary matrix V that trans•orns from the normalizcd E, basis to the nor malizcd P basis. [1]) d. Expand f(r) =5r? -3r + I in terns of the nomnalizcd versions of both bases, and verify tlhat the transformnation matrix U coverts the P-basis cxpansion of f() into its F-basis cxpansion. (2+2-+1]

Qucstion 2 Thc ON set of functions (over a suitablc rangc of z, y, ) given by

B ={lo) = Crc-. Jo) = Cye-r, Jos) = Czc-r}}spans spans^ aa^ threcthrec dimemsional voctor

space ol functions. V. a. ind the matrix reprcscnt ation, M, of the operator Lr = -i(y -)in the B;

basis. (3)

b. IVhat are the cigenvalucs of M and the corresponding cigenvectors? (

C. Writc the cxplicit form of M' which is thc matrix M writton in a dilcrent ON basis,

B = {lo)lo,)lo3)} using the unitary givcn below (The matrix elements of U are

Uij i= (0,, o;)) (2):

æ=

0 1//2 -i/V 0 1/V2 i/

d. Calculate the cxpcctation valucs of the matrix MM w.rt. lo), o,),lo). 3| c. Calculatc the expectation valucs of the matrix Mw.r.t. lo),).l). (

Qucstion 3 A, B.C arc finitc-dimensional Hormitian matrices such that C=A+B and A, B) = 0. The ON cigonvectors of Aare u)u2).... u,). a. (^) Writc downthc mitary (^) transformation to (^) digonalize Cin terms of (^) u;),i= (^) 1,2,.... n.

b. (^) Consider tlhe natrix D= (^) A' - (^) AB + A (^) BA + B + B, (^) cvaluatc the (^) conmntator

|D,C1. (3|

c. Lct. A and B be positive-dcfnite matrices and

and that for B be A 9osuch that A + Ap = 1 with the same corresponling cige

vcctor. All^ other (^) cigenval1es of A (^) and B arc (^) less thap (^) 1/2. Find the (^) cxpcct ation (^) value (uC)when ) is a unit-nornalizcd vector 3

the largcst cigenvalue of Abe Aa

Question 1 (a) Develop the Laurent series expansion of f(z) = [z(z-1)]-1 about the point z= 1 valid for small values of z - 1|. Specify the range over which this expansion holds. [2) (b) Develop the Laurent series expansion of f(z) = (z(z - 1))-' about the point

valid for small values of zl. Specify the range over which this expansion holds. 2

(e) Show that the two expansions obtained in (a) and (b) above are analytic

than 10. 4|

Question 2 (a) Show that all roots of f(z) = z 4 + 996407 have modlus less

(b) Use the Cauchy principal value concept to show that ( with 0 <p<1),

T-drd = C^ cot(Ca(p))

Question 3 Evaluate the integral tan-

n=

where C is a constant and C%(p) is a function of p. You may need to use cot z (^) =n-oo z-ne^1 [6]

de

roo In(1 t+ c) 1+a

Z= 0

-dc

for aand bpositive with ab < 1, by choosing appropriate contours and checking that the (^) integrand (^) satisfies the (^) necessary conditions on (^) different parts of the (^) contour.

Question 4 Evaluate the integral,

(2)

(3)

choosing appropriate contours and checking that the integrand satisies the necessary conditions on different parts of the contour. 10| Question 5 (a) The matrices, La, Ly, Lz, representing angular momentum components are all Hermitian. Show that the eigenvalues of L? = L2 + L3+ L are

real and nonnegative. 5]

(b) Expand the function e* in terms of the Laguerre polynomials L() which are orthonormal on the range 0 S a <0 with scalar product (flg) = f(e)g(z)e-*dr, keeping only the first four terms in the expansion. The first four In(z) are Lo =1, L = 1-,Lz = (2- 4e +)/2, La = (6 18t+9r? -a)/6. [5)

continuations of each other. For this you may need to use the result that () an-s

F(

(|+|=

f<)=

|4 ai^ o:(s)

aiQi() =

(oi}:avbitray

{wi}: ON

<t, f> Nom^ <0i^ ¢:=^ Si:0N^ basis

b= Ac (^) ’ bi= Aiji

a;e C

|\s I|f||^ |lgl|^ Schwavz^

Ineq,vality

J

A'= UAU =UAyl

H=H: hermitiom

I|f1>slai'^ iBesse^

Lneyvalityo: conplete

2 l4i><4il=I^ :cosure^

Aajl4i><4i|^

A72 ldi<ai

<Atf, g>=^ <f,^ Ag>^ A=^ ¿ A

li><l;Aj=^

<4ilAlQi)

LA, AtJ=:A normal

{oi(3:basis

If {>)

H |

(oi,W}:oN

’{0}: GvamSchmidt^ orthoganalisatton

If eqrali t

ji=<i, i)

LHy H2]=0^ H,^

Ha3:CScO

a'> Va

2il2i complete

ith^ pssi^ tlon

=Jf*g ds:IP

an= <nyf)

bË= a, <V;,i)

ai= a

<f\Alg) =Constant^ (under^ U)

2*= ireal^ eig^ envalves

{(iS}:basis (O N)

ç 'eigenvalves

ommute

diag onali's^ atbn

co mmon anplete

Corwwm ute Compatible C algenbasis