Practice Questions

Q14.A force →F = (5^i + 3^j + 2^k)N is applied over a particle which displaces it from its origin to the point →r = (2^i −^j)m. The work done on the particle in joules is (1) −7 (2) +7 (3) +10 (4) +13

Q16.A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particle takes place in a plane. It follows that (1) its velocity is constant (2) its acceleration is constant (3) its kinetic energy is constant (4) it moves in a straight line.

Q17.A wire fixed at the upper end stretches by length by applying a force F. The work done in stretching is (1) F/2 (2) Fℓ (3) 2 Fℓ (4) Fℓ/2

Q19.One solid sphere A and another hollow sphere B are of same mass and same outer radii. Their moment of inertia about their diameters are respectively IA and IB such that (1) IA = IB (2) IA > IB (3) IA < IB (4) yes, 45∘IA/IB = dA/dB Where dA and dB are their densities.

Q21.The time period of an earth satellite in circular orbit is independent of (1) the mass of the satellite (2) radius of its orbit (3) both the mass and radius of the orbit (4) neither the mass of the satellite nor the radius of its orbit.

Q24.Spherical balls of radius R are falling in a viscous fluid of viscosity η with a velocity v. The retarding viscous force acting on the spherical ball is JEE Main 2004 JEE Main Previous Year Paper (1) directly proportional to R but inversely (2) directly proportional to both radius R and proportional to v. velocity v. (3) inversely proportional to both radius R and (4) inversely proportional to R but directly velocity v. proportional to velocity v.

Q31.Which of the following statements is correct for any thermodynamic system? (1) The internal energy changes in all processes. (2) Internal energy and entropy are state functions. (3) The change in entropy can never be zero. (4) The work done in an adiabatic process is always zero.

Q36.The total energy of particle, executing simple harmonic motion is (1) ∝X (2) ∝x2 (3) independent of x (4) ∝x1/2

Q39.The displacement y of a particle in a medium can be expressed as y = 10−6 sin(110t + 20x + π/4)m, where t is in seconds and x in meter. The speed of the wave is JEE Main 2004 JEE Main Previous Year Paper (1) 2000 m/s (2) 5 m/s (3) 20 m/s (4) 5πm/s

Q43.A charged oil drop is suspended in a uniform field of 3 × 104 V/m so that it neither falls nor rises. The charge on the drop will be (take the mass of the charge = 9.9 × 10−15 kg and g = 10 m/s2 ) (1) 3.3 × 10−18C (2) 3.2 × 10−18C (3) 1.6 × 10−18C (4) 4.8 × 10−18C

Q50.A piece of copper and another of germanium are cooled from room temperature to 77 K, the resistance of (1) each of them increases (2) each of them decreases (3) copper decreases and germanium increases (4) copper increases and germanium decreases

Q52.The materials suitable for making electromagnets should have (1) high retentivity and high coercivity (2) low retentivity and low coercivity (3) high retentivity and low coercivity (4) low retentivity and high coercivity

Q53.A current I ampere flows along an infinitely long straight thin-walled tube, then the magnetic induction at any point inside the tube is (1) infinite (2) zero μ0 2i (3) tesla (4) 2n2 B r 4π

Q57.A coil having n turns and resistance 4RΩ. This combination is moved in time t seconds from a magnetic field W1 weber to W2 weber. The induced current in the circuit is (1) −W2−W15Rnt (2) −(W2−W1)5Rt (3) −W2−W1Rnt (4) −n(W2−W1)Rt

Q59.A metal conductor of length 1 m rotates vertically about one of its ends at angular velocity 5 radians per second. If the horizontal component of earth's magnetic field is 0.3 × 10−4 T, then the e.m.f. developed between the two ends of the conductor is (1) depends on the nature of the metal used (2) depends on the intensity of the radiation (3) depends both on the intensity of the radiation and (4) is the same for all metals and independent of the the metal used intensity of the radiation.

Q60.Alternating current can not be measured by D.C. ammeter because (1) A.C. cannot pass through D.C. (2) A.C. changes direction (3) average value of current for complete cycle is (4) D.C. ammeter will get damaged. zero

Q61.In an LCR series a.c. circuit, the voltage across each of the components, L, C and R is 50 V . The voltage across the LC combination will be (1) 50 V (2) 50√2 V (3) 100 V (4) 0 V (zero)

Q62.In a LCR circuit capacitance is changed from C to 2C . For the resonant frequency to remain unchanged, the inductance should be changed from L to (1) 4 L (2) 2 L (3) L/2 (4) L/4 JEE Main 2004 JEE Main Previous Year Paper

Q66.The angle of incidence at which reflected light totally polarized for reflection from air to glass (refractive index n ), is (1) sin−1(n) (2) sin−1(1/n) (3) tan−1(1/n) (4) tan−1(n)

Q69.According to EInstein's photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal Vs the frequency, of the incident radiation gives straight line whose slope JEE Main 2004 JEE Main Previous Year Paper (1) depends on the nature of the metal used (2) depends on the intensity of the radiation (3) depends both on the intensity of the radiation and (4) is the same for all metals and independent of the the metal used intensity of the radiation.

Q71.The manifestation of band structure in solids is due to (1) Heisenberg's uncertainty principle (2) Pauli's exclusion principle (3) Bohr's correspondence principle (4) Boltzmann's law

Q76.When p-n junction diode is forward biased (1) the depletion region is reduced and barrier height (2) the depletion region is widened and barrier height is increased is reduced (3) both the depletion region and barrier height (4) both the depletion region and barrier height reduced increased. Q77. 6.02 × 1020 molecules of urea are present in 100ml of its solution. The concentration of urea solution is (1) 0.001M (2) 0.1M (3) 0.02M (4) 0.01M

Q1. The length of a simple pendulum executing simple harmonic motion is increased by 21%. The percentage increase in the time period of the pendulum of increased length is (1) 11% (2) 21% (3) 42% (4) 10%

Q2. Dimension of 1 , where symbols have their usual meaning, are μ0ε0 (1) [L−1 T] (2) [L−2 T2] (3) [L2 T−2] (4) [LT−1]

Q5. The co-ordinates of a moving particle at any time ' t ' are given by x = αt3 and y = βt3 . The speed of the particle at time ' t ' is given by (1) 3t√α2 + β2 (2) 3t2√α2 + β2 (3) t2√α2 + β2 (4) √α2 + β2