Practice Questions

Q19.A body A of mass M while falling vertically downwards under gravity breaks into two parts; a body B of mass 1/3M and a body C of mass 2/3M. The centre of mass of bodies B and C taken together shifts compared to that of body A towards (1) depends on height of breaking (2) does not shift (3) body C (4) body B

Q24.Average density of the earth (1) does not depend on g (2) is a complex function of g (3) is directly proportional to g (4) is inversely proportional to g

Q27.If S is stress and Y is Young's modulus of material of a wire, the energy stored in the wire per unit volume is (1) 2S 2Y (2) S 2/2Y (3) 2Y /S 2 (4) S/2Y

Q30.Which of the following is incorrect regarding the first law of thermodynamics? (1) It is applicable to any cyclic process (2) It is a restatement of the principle of conservation of energy (3) It introduces the concept of the internal energy (4) It introduces the concept of the entropy

Q32.A system goes from A to B via two processes I and II as shown in the figure. If ΔU1 and ΔU2 are the changes in internal energies in the processes I and II respectively, the (1) ΔU1 = ΔU2 (2) relation between ΔU1 and ΔU2 can not be determined (3) ΔU2 > ΔU1 (4) ΔU2 < ΔU1

Q36.If a simple harmonic motion is represented by d2x + αx = 0, its time period is dt2 (1) 2π (2) 2π α √α (3) 2πα (4) 2π√α

Q39.An observer moves towards a stationary source of sound, with a velocity one fifth of the velocity of sound. What is the percentage increase in the apparent frequency? (1) zero (2) 0.5% (3) 5% (4) 20%

Q44.A parallel plate capacitor is made by stacking n equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is C then the resultant capacitance is (1) (n −1)C (2) (n + 1)C (3) C (4) nC

Q50.An energy source will supply a constant current into the load of its internal resistance is (1) equal to the resistance of the load. (2) very large as compared to the load resistance. (3) zero. (4) non-zero but less than the resistance of the load.

Q53.A magnetic needle is kept in a non-uniform magnetic field. It experiences (1) a torque but not a force (2) neither a force nor a torque (3) a force and a torque. (4) a force but not a torque.

Q54.Two thin, long parallel wires separated by a distance 'd' carry a current of 'i' A in the same direction. They will (1) attract each other with a force of μ0i2/(2πd) (2) repel each other with a force of μ0i2/(2πd) (3) attract each other with a force of μ0i2 (2πd2) (4) repel each other with a force of μ0i2 /(2πd2)

Q56.A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity then (1) its velocity will decrease. (2) its velocity will increase. (3) it will turn towards right of direction of motion. (4) it will turn towards left of direction of motion

Q57.A charged particle of mass m and charge q travels on a circular path of radius r that is perpendicular to a magnetic field B. The time taken by the particle to complete one revolution is (1) 2πmq (2) 2πq2B B m (3) 2πqB (4) 2πm m qB

Q61.A circuit has a resistance of 12Ω and an impedance of 15Ω. The power factor of the circuit will be (1) 0.8 (2) 0.4 (3) 1.25 (4) 0.125

Q65.A Young’s double slit experiment uses a monochromatic source. The shape of the interference fringes formed on a screen is (1) hyperbola (2) circle (3) straight line (4) parabola JEE Main 2005 JEE Main Previous Year Paper

Q67.When an unpolarized light of intensity I0 is incident on a polarizing sheet, the intensity of the light which does not get transmitted is (1) 1 2 I0 (2) 41 I0 (3) zero (4) I0

Q71.The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy ? (1) III (2) IV (3) I (4) II

Q74.If radius of 2713Al nucleus is estimated to be 3.6 Fermi then the radius 12552 Te nucleus be nearly JEE Main 2005 JEE Main Previous Year Paper (1) 6 fermi (2) 8 fermi (3) 4 fermi (4) 5 fermi

Q75.A nuclear transformation is denoted by X(n, α)73Li. Which of the following is the nucleus of element X ? (1) 12C6 (2) 105 B (3) 95 B (4) 114 Be

Q77.In a common base amplifier, the phase difference between the input signal voltage and output voltage is (1) π (2) π 4 (3) 0 (4) π2

Q78.In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be (1) 50 Hz (2) 25 Hz (3) 100 Hz (4) 70.7 Hz

Q1. If →A × →B = →B × →A, then the angle between A and B is (1) π (2) π/3 (3) π/2 (4) π/4

Q2. Which one of the following represents the correct dimensions of the coefficient of viscosity? (1) ML−1 T−2 (2) MLT−1 (3) ML−1 T−1 (4) ML−2 T−2

Q9. Two masses m1 = 5 kg and m2 = 4.8 kg tied to a string are hanging over a light frictionless pulley. What is the acceleration of the masses when lift free to move (g = 9.8 m/s2) (1) 0.2 m/s2 (2) 9.8 m/s2 (3) 5 m/s2 (4) 4.8 m/s2

Q12.Which of the following statements is false for a particle moving in a circle with a constant angular speed? (1) The velocity vector is tangent to the circle. (2) The acceleration vector is tangent to the circle. (3) The acceleration vector points to the centre of the (4) The velocity and acceleration vectors are circle. perpendicular to each other.