Tuesday, March 1, 2011



      3mark questions
1. Two concentric spherical shells with radius r1 and r2 with the outer shell earthed and the inner shell is given +Q charge .what is the capacitance?

2.Which of the following is true for two non commuting operators
a) Both operators have equal eigen values
b)Both may have common eigen vectors
c)Both never have common eigen vectors
d)Both have equal eigen vectors
Ans: c

3. Diagonal elements of a skew hermitian matrix are

a) Zero
b) imaginary
c) real
d) Either zero or purely imaginary
Ans: d

4. If ψ=exp (-lamda*x)then <x^2>-(<x>)^2 is

a) Zero
b) 4/lamda^3
c) 3/ lamda^3
d) 2/ lamda^3
5. Which of d following has max angle of diffraction when it is passed
      through a straight edge hole?
            a) Blue
           b)  Red    ... Ans: b
6. Three polarizer’s second is 45 degree with the line of axis of first and the third is 90 degree with first. Final intensity is
Ans: I/8
7. A pion (of rest mass 135Mev.) is decays in to 2 photons with E
100mev each. What is the velocity of pion...?
Ans: 0.74c
8. The value of (d/dx - x) (d/dx + x) is
Ans:d^2/dx^2 –x d/dx- x^2+1
9. Given entropy S = A (EV) ^1/3, then calculate the temperature at A=E=V=1?
a) 3 b) 1/3 c) 1  d)ln2

10.About Cu(atomic number29)
         a)Cu+ shows ESR spectra, Cu++ doesn't
         b)Cu++ shows ESR and Cu+ doesn't
          c) Both Cu+ and Cu++ doesn't show ESR spectra
         d) Both shows ESR spectra
Ans: b

11. If {x p} =1 then Poisson's bracket of {x^2+p^2,p} is?

12. A circular wire of R radius having resistance per unit length p. If a wire of same resistance per unit length is connected between two opposite point A and B of circular wire then what will be the equivalent resistance between these two points-

Ans- 0.9pR

 13. E = E0cos(kx-wt) i- E0sin(kx-wt)j, then electromagnetic wave is
a) Plane polarized
b)Elliptically polarized
c)Circularly polarized
d) Unpolarized
14. Three states of energies 0k beta, 1k beta and 2k beta. In equilibrium, total energy is 1000 k beta, approximate number of particles are
a) 1400
b) 2400
c) 3200
d) 4400
15. If H|1>=|2> and H|2>=2|1>
what are the Eigen values of H.

Ans:+/- 2
Clue: The answer to H|1>=|2> problem should be +/- sqrt(2) since you shall have to operate H on both sides to get (H^2)|1>=H|2>=2|1> Now you get (H^2-2)|1>=0, the eigen value to H is indeed +/- sqrt(2)

16.  n number of voltage sources r connected in series(circular
shape),each have equal resistance, then voltage between one of d source
a) (n-1) v
 b) V
17. Consider two charges with considerable mass such that the electrostatic
& gravitational F is balance. If the distance is increased, then what is the effect of force...
a)   remains same  b)E. force will be larger c) g. force will be larger
 18. Consider a particle in a potential well ψ(x)=(l-x)    -L<X<0
                                                                =(L+X)  0<X<L
   X>L  THEN which of d following is not true.   a)<x>=3/2
b)<x>=0 c)stationary state d)probability is half in first region

19.  CONSIDER a particle in Harmonic Oscillator Then E= (n+1/2)
h/6.28*w   then degree of degeneracy...
   a)n+1 b)(n*n+3n+2)/2 ....etc
20. If H=F (tp*p)+1/2kx*x, then
  a)total E&P is conserved ,b).....
21. A particle has a wave function ψ &has potential 1/2kx*x, then time period
22. Consider a circular wire of radius R. mark any diameter AB. THEN
resistance between the points A&B is
23 .f = x^2+y^2 +2ixy, g=x^2+y^2-2ixy
 Then a) f &g are not analytic..
           b) f is only analytic
            c) g is only analytic
            d) Both are analytic
Ans : a
24. integral(z/sinz)
   a) has single pole   b)branch points....
25. Consider parallel plate capacitor separated by fixed distance.  If 1 of
the capacitor is tilted such that the distance between them is minimum then
 a) c is increasing  b)c is decreasing
26. 2 equal charges tied by a string. The tension of the string is T due to repulsive force. If another equal charge is placed at the midpoint of them. What will be the tension of the string?
27.   Water has latent heat capacity ....calculate work done to convert
1 liter water....
28. Given wave vector k= (x^+y^)/2..., amplitude of energy is E0, then magnetic field is....
29.Half life of carbon 12 is 5600years..Time required to become its 1/8
Ans: 16800y
30. Given potential V(x) = (Ax+B)-2V0, then Eigen energy is...
31. A ball fall from a height h time to reach ground is t then for the first bounce time t/2 and so on .then at what time it will be at rest?
32. A girl sit and swings suddenly stands what will happen to time period?

33. if the displacement term is not there in Maxwell’s equation what will turn out to be wrong?
A) Continuity equation
34. Which one Ne, He, co, co2 have larger average velocity?
35. for n two level system, the system in the excited state will be
a) n/2
b) n
c) 0
d) 3n/4....
36. An unstretchable wire is attached at ceiling a mass attached its end then a spring with a mass is attached to its end. What is the degree of freedom of the system?
a) 5
b) 6
c) 3
d) 4

37.a dimensional analysis problem. Related with coefficient of viscosity, density etc

pls send me if u know more questions and answers……….your feedback is so important since all this from memory and may therefore some errors…this questions are recollected by suja karivellur,sooraj p,laveen p v korom,preethi korom, dilna puthiyatheru , rasmi c k iisc
Pls send feedbacks to     soorajpmg@gmail.com

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