As you want to get the Joint Entrance Screening Test last year question papers so here it is for you:


1. Black-body radiation, at temperature Ti fills a volume V. The system expands adiabatically
and reversibly to a volume 8V. The final temperature Tf = xTi, where the factor x is equal to
(a) 0.5 (b) 2.8 (c) 0.25 (d) 1
2. A particle of mass m, constrained to move along the x-axis. The potential energy is given
by, V(x)=a + bx +cx2, where a, b and c are positive constants. If the particle is disturbed
slightly from its equilibrium position, then it follows that
(a) it performs simple harmonic motion with period 2 (m/2c)
(b) it performs simple harmonic motion with period 2 (ma/2b2)
(c) it moves with constant velocity
(d) it moves with constant acceleration

3. Consider a square ABCD, of side a, with charges +q, -q, +q, -q placed at the vertices, A, B,
C, D respectively in a clockwise manner. The electrostatic potential at some point located
at distances r (where r >> a) is proportional to
(a) a constant (b) 1/r (c) 1/r2 (d) 1/r3

4. The general solution of dy/dx – y = 2ex is (C is an arbitrary constant)
(a) e2x+Cex (b) 2xex+Cex (c) 2xex+C (d) ex2+C

5. As 0, lim _
_
_
__
_ 


sin
) sin 1 ln(
is
(a) (b) -(c) 1 (d) 0

6. If P^ is the momentum operator, and ^ are the three Pauli spin matrices, the eigenvalues
of (^.P^) are
(a) px and pz (b) px ipy (c) |p| (d) (px + py +pz)

7. Two parallel infinitely long wires separated by a distance D carry steady currents I1 and I2
(I1 > I2) flowing in the same direction. A positive point charge moves between the wires
parallel to the currents with a speed v at a distance D/2 from either wire. The magnitude of
an electric field that must be turned on to maintain the trajectory of the particle is
proportional to
(a) (I1-I2)v/D (b) (I1+I2)v/D (c) (I1-I2)v2/D2 (d) (I1+I2)v2/D2

8. An ideal gas of non-relativistic fermions in three dimensions is at a temperature of 0 K.
When both the mass of the particles and the number density are doubled, the energy per
particle is multiplied by a factor,
(a) 2 (b) 1 (c) 21/3 (d) 1/21/3

9. The rotational part of the Hamiltonian of a diatomic molecule is (1/2 1)(Lx
2+Ly
2)
+ (1/2 2) Lz
2 where 1 and 2 are moments of inertia. If 1 = 22, the three
lowest energy levels (in units of h2/4 2) are given by
(a) 0, 2, 3 (b) 0, 1, 2 (c) 1, 2, 3 (d) 0, 2, 4

10. A particle of mass 1 gm starts from rest and moves under the action of a force of 30
Newtons defined in the rest frame. It will reach 99% the velocity of light in time
(a) 9.9 x 103 sec (b) 7 x 104 sec (c) 0.999 sec (d) 0.7 sec

Sample Questions for JEST inTheoretical Computer Science:

1. Select the correct alternative in each of the following:
(a) Let a and b be positive integers such that a > b and a2 - b2 is a prime number.
Then a2 - b2 is equal to
(A) a - b (B) a + b (C) a × b (D) none of the above
(b) When is the following statement true? (A [ B) \ C = A \ C
(A) If ¯ A \ B \ C = _ (B) If A \ B \ C = _ (C) always (D) never
(c) If a fair die (with 6 faces) is cast twice, what is the probability that the two
numbers obtained di_er by 2?
(A) 1/12 (B) 1/6 (C) 2/9 (D) 1/2
(d) T(n) = T(n/2) + 2; T(1) = 1. When n is a power of 2, the correct expression for T(n)
is:
(A) 2(log n + 1) (B) 2 log n (C) log n + 1 (D) 2 log n + 1

2. Consider the following function, defined by a recursive program:
function AP(x,y: integer) returns integer;
if x = 0 then return y+1
else if y = 0 then return AP(x-1,1)
else return AP(x-1, AP(x,y-1))
(a) Show that on all nonnegative arguments x and y, the function AP terminates.
(b) Show that for any x, AP(x, y) > y.

3. How many subsets of even cardinality does an n-element set have ? Justify answer.

4. A tournament is a directed graph in which there is exactly one directed edge between
every pair of vertices. Let Tn be a tournament on n vertices.
(a) Use induction to prove the following statement:
Tn has a directed hamiltonian path (a directed path that visits all vertices).
(b) Describe an algorithm that finds a directed hamiltonian path in a given tournament.
Do not write whole programs; pseudocode, or a simple description of the
steps in the algorithm, will suffice. What is the worst case time complexity of
your algorithm?

5. Describe two different data structures to represent a graph. For each such
representation, specify a simple property about the graph that can be more
efficiently checked in that representation than in the other representation. Indicate
the worst case time required for verifying both of your properties in either
representation.

6. Two gamblers have an argument. The first one claims that if a fair coin is tossed
repeatedly, getting two consecutive heads is very unlikely. The second, naturally,
is denying this. They decide to settle this by an actual trial; if, within n coin
tosses, no two consecutive heads turn up, the first gambler wins.
(a) What value of n should the second gambler insist on to have more than a 50%
chance of winning?
(b) In general, let P(n) denote the probability that two consecutive heads show up
within n trials. Write a recurrence relation for P(n).
(c) Implicit in the second gambler’s stand is the claim that for all sufficiently large n,
there is a good chance of getting two consecutive heads in n trials; i.e. P(n) > 1/2.
In the first part of this question, one such n has been demonstrated. What
happens for larger values of n? Is it true that P(n) only increases with n? Justify
your answer.

7. Consider the following program:
function mu(a,b:integer) returns integer;
var i,y: integer;
begin
---------P----------
i = 0; y = 0;
while (i < a) do
begin --------Q------------
y := y + b ;
i = i + 1
end
return y
end
Write a condition P such that the program terminates, and a condition Q which is
true whenever program execution reaches the place marked Q above.