Q9
NAT • 2M
Quantitative & Analytical Aptitude
The binary operation □ is defined as a □ b = ab+( a+b), where a and b are any two real numbers. The value of the identity element of this operation, defined as the number x such that a □ x = a, for any a, is . (A) 0 (B) 1 (C) 2 (D) 10 - GA Set-2 3/3
Q33
NAT • 1M
Nuclear & Particle Physics
The direction of ∇ሬሬ݂⃗for a scalar field ݂(ݔ,ݕ ,ݖ )= ଵ ଶݔଶ -ݕݔ+ ଵ ଶݖଶ at the point ܲ(1, 1, 2) is (A) 5 ˆ2ˆ k j (B) 5 ˆ2ˆ k j (C) 5 ˆ2ˆ k j (D) 5 ˆ2ˆ k j
Q37
NAT • 2M
Nuclear & Particle Physics
Atoms, which can be assumed to be hard spheres of radius R, are arranged in an fcc lattice with lattice constant a, such that each atom touches its nearest neighbours. Take the center of one of the atoms as the origin. Another atom of radius r (assumed to be hard sphere) is to be accommodated at a position (0, a/2, 0) without distorting the lattice. The maximum value of r/R is ________. (Give your answer upto two decimal places)
Q38
NAT • 2M
Nuclear & Particle Physics
In an inertial frame of reference S, an observer finds two events occurring at the same time at co- ordinates 01 x and .2 d x A different inertial frame S moves with velocity v with respect to S along the positive x-axis. An observer in S also notices these two events and finds them to occur at times 1t and 2t and at positions 1x and ,2x respectively. If 1 2t t t , 1 2x x x and 2 2v1 1 c , which of the following statements is true ? (A) d x t , 0 (B) d x t , 0 (C) d x c d t , v2 (D) d x c d t , v2 6/10
Q39
NAT • 2M
Nuclear & Particle Physics
The energy vs. wave vector k E relationship near the bottom of a band for a solid can be approximated as 42 ) ( ) (ka B ka A E , where the lattice constant a = 2.1 Å. The values of A and B are J, 10 2 . 3 and J 10 3 . 62019 respectively. At the bottom of the conduction band, the ratio of the effective mass of the electron to the mass of free electron is _______. (Give your answer upto two decimal places) (Take =1.05x10-34 J-s, mass of free electron= 9.1x10-31 kg)
Q45
NAT • 2M
Nuclear & Particle Physics
The Fermi energies of two metals X and Y are 5 eV and 7 eV and their Debye temperatures are 170 K and 340 K, respectively. The molar specific heats of these metals at constant volume at low temperatures can be written as 3T A TC XXXV and ,3T A T CYYYV where γ and A are constants. Assuming that the thermal effective mass of the electrons in the two metals are same, which of the following is correct? (A) 8 ,5 7 Y X Y X A A (B) 8 1,5 7 Y X Y X A A (C) 8 1,7 5 Y X Y X A A (D) 8 ,7 5 Y X Y X A A
Q50
NAT • 2M
Quantum Mechanics
Let m l, be the simultaneous eigenstates of 2L and zL . Here L is the angular momentum operator with Cartesian components ( ) , ,z y xL L L, l is the angular momentum quantum number and m is the azimuthal quantum number. The value of is 1 , 1 ) ( 0 , 1 y xiL L (A) 0 (B) (C) 2 (D) 3
Q55
NAT • 2M
Nuclear & Particle Physics
A particle of mass m and energy E, moving in the positive x direction, is incident on a step potential at x = 0, as indicated in the figure. The height of the potential is V0, where V 0 > E. At 0 where ,00 x x x , the probability of finding the electron is 1 /e times the probability of finding it at x = 0. If 2 0 ) ( 2 E V m , the value of x0 is (A) 2 (B) 1 (C) 2 1 (D) 4 1 END OF THE QUESTION PAPER x = x0 V0 E x = 0 Q. No Type Section Key Marks 1 MCQ GA B 1 2 MCQ GA A 1 3 MCQ GA D 1 4 MCQ GA C 1 5 MCQ GA B 1 6 MCQ GA C 2 7 MCQ GA C 2 8 MCQ GA C 2 9 MCQ GA A 2 10 MCQ GA C 2 1 MCQ PH D 1 2 MCQ PH C 1 3 MCQ PH C 1 4 NAT PH 0 : 0 1 5 MCQ PH A 1 6 MCQ PH B 1 7 NAT PH 4 : 4 1 8 NAT PH 0.25 : 0.25 1 9 NAT PH 0.5 : 0.5 1 10 MCQ PH A 1 11 NAT PH 2 : 2 1 12 MCQ PH A 1 13 NAT PH 9 : 9 1 14 MCQ PH C 1 15 MCQ PH A 1 16 MCQ PH B 1 17 NAT PH 1.72 : 1.74 1 18 NAT PH 400 : 400 1 19 NAT PH 2.41 : 2.49 1 20 MCQ PH B 1 21 MCQ PH B 1 22 MCQ PH A 1 23 NAT PH 2 : 2 1 24 NAT PH 2 : 2 1 25 MCQ PH C 1 26 MCQ PH D 2 27 NAT PH 12 : 12 ; 6 : 6 2 28 MCQ PH C 2 29 MCQ PH B 2 30 NAT PH 24 : 24 2 31 NAT PH 80 : 80 2 32 MCQ PH D 2 33 MCQ PH B 2 34 MCQ PH C 2 35 NAT PH 26.65 : 26.68 2 36 MCQ PH A 2 37 NAT PH 0.40 : 0.42 2 38 MCQ PH C 2 39 NAT PH 0.20 : 0.24 2 40 MCQ PH D 2 41 NAT PH 18 : 18 2 42 MCQ PH A 2 43 NAT PH 4 : 4 2 44 MCQ PH B 2 45 MCQ PH A 2 46 MCQ PH D 2 47 NAT PH 1.40 : 1.45 2 48 MCQ PH D 2 49 MCQ PH D 2 50 MCQ PH C 2 51 MCQ PH B 2 52 NAT PH 5.5 : 5.9 2 53 NAT PH 0.27 : 0.29 2 54 MCQ PH B 2 55 MCQ PH C 2