Title NT 21 PAPER.pdf ✅

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PHYSICS (Section A) 1. The respective number of significant figures for the number 24.403, 2.1 × 10–3 , 0.0003 and 0.4 × 104 (A) 5, 2, 1, 1 (B) 5, 2, 1, 2 (C) 5, 2, 4, 2 (D) 5, 5, 4, 1 2. An object is moving in negative direction with a negative acceleration. The velocity- time graph with constant acceleration which represents the above situation is : (A) (B) (C) (D) 3. Same force acts on two bodies of different masses 8 kg and 10 kg initially at rest. The ratio of times required to acquire same final velocity is : (A) 1 : 1 (B) 8 : 11 (C) 4 : 5 (D) 2 : 3 4. In a projectile motion, where is the angular momentum minimum ? (A) At the starting point (B) On the landing point (C) Highest point of projectile (D) As no such position 5. If the gravitational force had varied as r–5/2 instead of r–2 , the potential energy of a particle at a distance r from the centre of the Earth would be proportional to : (A) r 3/2 (B) r –3/2 (C) r (D) r –5/2 6. The two spheres, one of which is hollow and other solid, have identical masses and moment of inertia about their respective diameters. The ratio of their radii is given by (A) 5 : 7 (B) 3 : 5 (C) 3 : 5 (D) 3 : 7 7. The length of a metal wire is 10 cm when the tension in it is 20 N and 12 cm when the tension is 40 N. Then natural length of the wire is (in cm) (A) 6 (B) 4 (C) 8 (D) 9 8. A small hole is made at a height of 1 3 from the bottom of the cylindrical water tank and at a depth of h = 1.71 m from the upper level of water in the tank. What is the distance, where the water emerging form the hole strike the ground ? (A) 6 m (B) 4 m (C) 3 m (D) 2 m 9. A vertical spring carries a 5 kg body and is hanging in equilibrium an additional force is applied so that the spring is further stretched. When released from this position, it performs 50 complete oscillations in 25 s, with an amplitude of 5 cm. The additional force applied is (A) 80 N (B) 80  2 N (C) 39.5 N (D) 4 N 10. A solid cylinder of mass M and radius R rolls down an inclined plane of height h. The angular velocity of the cylinder when it reaches the bottom of the plane will be (A) 1 gh 2R (B) 2 gh R (C) 2 gh R 3 (D) 2 gh R 2 PW – AITS_NT-21
11. For equilibrium of the system, value of mass m should be (A) 9 kg (B) 15 kg (C) 21 kg (D) 1 kg 12. A and B are the two concentric circular conductors of center O and carrying currents I1 and I2 as shown in the adjacent figure. If ratio of their radii is 1 : 2 and ratio of the flux densities at O due to A and B is 1 : 3 then the value of I1/I2 is : (A) 1/6 (B) 1/4 (C) 1/3 (D) 1/2 13. The frequency of a whistle of an engine is 660 cycles/sec is moving with the speed of 30 m/sec towards an observer. The apparent frequency will be (velocity of sound = 330 m/s) (A) 600 cps (B) 726 cps (C) 990 cps (D) 330 cps 14. A particle of mass 3 kg is moving along x-axis and its position at time t is given by equation x = (2t2 + 5) m. Work done by all the force acting on it in time interval t = 0 to t = 3 s is : (A) 144 J (B) 72 J (C) 108 J (D) 216 J 15. If a force of 9 N is acting on a body, then find instantaneous power supplied to the body when its velocity is 5 m/s in the direction of force (A) 195 watt (B) 45 watt (C) 75 watt (D) 100 watt 16. A magnet of moment 4 Am2 is kept suspended in a magnetic field of induction 5 × 10–5 T. The work done in rotating it through 180° is : (A) 4 × 10–4 J (B) 5 × 10–4 J (C) 2 × 10–4 J (D) 10–4 J 17. The magnetic field B and the magnetic intensity H in a material are found to be 1.6T and 1000 A/m respectively. Calculate the relative permeability μr and the susceptibility  of material. (A) 1.3 × 10–3 each (B) 1.3 × 103 each (C) 3.1 × 10–3 each (D) 3.1 × 103 each 18. Find the temperature of junction at B, if each rod has equal area of cross-section. B 20°C L 40°C k 2k C 100°C L A k 2L D (A) 90 °C 7 (B) 50 °C 7 (C) 380 °C 7 (D) 280 °C 5 19. When a process is taken from process abc 100 J of heat is absorbed by system and 50 J of work is done by it. If work done in process adc is 60 J, then heat absorbed in this process c b P V d a (A) 200 J (B) 250 J (C) 110 J (D) 90 J 20. A sample of ideal gas ( = 1.4) is heated at constant pressure. If an amount of 140 J heat is supplied to the gas, then change in internal energy of the gas (A) 40 J (B) 120 J (C) 100 J (D) 50 J
21. Two capacitors C1 = C and C2 = 3C are connected as shown in figure. Initially, key K is open and capacitor C1 holds charge Q. after closing the key K, the charge on each capacitor at steady state will be : (A) Q Q , 4 4 (B) Q 3Q , 4 4 (C) 3Q 3Q , 4 4 (D) Q ,Q 3 22. The linear charge density of the semicircular ring on both side is same in magnitude. The electric field intensity at O is along (A) ˆ i (B) ˆ −i (C) ˆ j (D) ˆ − j 23. An electric dipole having moment p is placed in uniform electric field of magnitude E.  be the angle between dipole moment and electric field vectors. Unstable equilibrium position of the dipole corresponds to (A)  = 0° (B)  = 90° (C)  = 180° (D)  = 120° 24. An alternating voltage is given by : 1 2 e = e sinωt +e cosωt Then the root mean square value of voltage is given by : (A) 2 2 1 2 e +e (B) 1 2 ee (C) 1 2 ee 2 (D) 2 2 1 2 e + e 2 25. The maximum value of alternating emf E in the given circuit will be : VL = 40 V ~ E = 50Hz VR = 80 V VC = 100 V (A) 220 V (B) 140 V (C) 100 V (D) 20 V 26. In the given circuit bulbs are rated as B1 (50w, 220V) B2(50w, 220V) B3(220V, 50w) B4(50w, 220V) & B5(220V, 100w) Among these bulbs which glow brightest? (A) B1 (B) B3 (C) B5 (D) All of these 27. The specific resistance of manganin is 50 × 10–8 –m. The resistance of a cube of length 50 cm about any two phase will be (A) 10–6  (B) 2.5 × 10–5  (C) 10–8  (D) 5 × 10–4  28. A p-type semiconductor can be obtained by adding (A) Antimony to pure germanium (B) Phosphorous to pure germanium (C) arsenic to pure silicon (D) gallium to pure silicon 29. The charge on the electron and protons is reduced to half. Let the present value of the Rydberg constant be R. What will be the new value of the Rydberg constant? (A) R/2 (B) R/4 (C) R/8 (D) R/16 30. In a radioactive substance at t = 0, the number of atoms is 8 × 104 . Its half life period is 3 year. The number of atoms 1 × 104 will remain after an interval of (A) 9 year (B) 8 year (C) 6 year (D) 24 year C1 C2 K + + + + X Y