Practice Questions

Q10.A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring reads 49 N , when the lift is stationary. If the lift moves downward with an acceleration of 5 m/s2 , the reading of the spring balance will be (1) 24 N (2) 74 N (3) 15 N (4) 49 N

Q11.Three forces start acting simultaneously on a particle moving with velocity, →v. These forces are represented in magnitude and direction by the three sides of a triangle ABC. The particle will now move with velocity (1) less than →v (2) greater than →v (3) |v| in the direction of the largest force BC (4) →v, remaining unchanged

Q15.A light spring balance hangs from the hook of the other light spring balance and a block of mass M kg hangs from the former one. Then the true statement about the scale reading is (1) Both the scales read Mkg each (2) The scale of the lower one reads Mkg and of the upper one zero (3) The reading of the two scales can be anything but (4) Both the scales read M/2 kg each the sum of the reading will be Mkg

Q16.A rocket with a lift-off mass 3.5 × 104 kg is blasted upwards with an initial acceleration of 10 m/s2 . Then the initial thrust of the blast is (1) 3.5 × 105 N (2) 7.0 × 105 N (3) 14.0 × 105 N (4) 1.75 × 105 N

Q22.Let →F be the force acting on a particle having position vector →r and →T be the torque of this force about the origin. Then → → → → → → (1)→r⋅ T = 0 and F. T ≠0 (2)→r⋅ T ≠0 and F ⋅ T = 0 → → → → → → (3)→r⋅ T ≠0 and F ⋅ T ≠0 (4)→r⋅ T = 0 and F ⋅ T = 0

Q23.The time period of a satellite of earth is 5 hours. If the separation between the earth and the satellite is increased to 4 times the previous value, the new time period will become JEE Main 2003 JEE Main Previous Year Paper (1) 10 hours (2) 80 hours (3) 40 hours (4) 20 hours

Q25.The escape velocity for a body projected vertically upwards from the surface of earth is 11 km/s. If the body is projected at an angle of 45∘ with the vertical, the escape velocity will be (1) 11√2 km/s (2) 22 km/s (3) 11 km/s (4) 11 km/s √2

Q26.A wire suspended vertically from one of its ends is stretched by attaching a weight of 200 N to the lower end. The weight stretches the wire by 1 mm. Then the elastic energy stored in the wire is (1) 0.2 J (2) 10 J (3) 20 J (4) 0.1 J

Q27.The earth radiates in the infra-red region of the spectrum. The spectrum is correctly given by (1) Rayleigh Jeans law (2) Planck's law of radiation (3) Stefan's law of radiation (4) Wien's law

Q28.According to Newton's law of cooling, the rate of cooling of a body is proportional to (Δθ)n , where Δθ is the difference of the temperature of the body and the surroundings, and n is equal to (1) two (2) three (3) four (4) one Q29."Heat cannot by itself flow from a body at lower temperature to a body at higher temperature" is a statement or consequence of (1) second law of thermodynamics (2) conservation of momentum (3) conservation of momentum (4) first law of thermodynamics

Q30.Which of the following parameters does not characterize the thermodynamic state of matter? (1) temperature (2) Pressure (3) Work (4) Volume

Q31.A Carnot engine takes 3 × 106cal. of heat from a reservoir at 627∘C, and gives it to a sink at 27∘C. The work done by the engine is (1) 4.2 × 106 J (2) 8.4 × 106 J (3) 16.8 × 106 J (4) Zero

Q36.The displacement of a particle varies according to the relation x = 4(cos πt + sin πt). The amplitude of the particle is (1) −4 (2) 4 (3) 4√2 (4) 8

Q37.A body executes simple harmonic motion. The potential energy (P.E), the kinetic energy (K.E) and total energy (T.E) are measured as a function of displacement x. Which of the following statements is true? (1) K.E. is maximum when x = 0 (2) T.E is zero when x = 0 (3) K.E is maximum when x is maximum (4) P.E. is maximum when x = 0

Q38.The displacement y of a wave travelling in the x-direction is given by y = 10−4 sin (600t −2x + π3 ) metres where x is expressed in metres and t in seconds. The speed of the wave-motion, in ms−1 , is (1) 300 (2) 600 (3) 1200 (4) 200

Q40.If the electric flux entering and leaving an enclosed surface respectively is ϕ1 and ϕ2 , the electric charge inside the surface will be JEE Main 2003 JEE Main Previous Year Paper (1) (ϕ2 −ϕ1)ε0 (2) (ϕ1 + ϕ2)/ε0 (3) (ϕ2 −ϕ1)/ε0 (4) (ϕ1 + ϕ2)ε0

Q43.A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor (1) decreases (2) remains unchanged (3) becomes infinite (4) increases

Q44.The work done in placing a charge of 8 × 10−18 coulomb on a condenser of capacity 100 micro-farad is (1) 16 × 10−32 joule (2) 3.1 × 10−26 joule (3) 4 × 10−10 joule (4) 32 × 10−32 joule

Q46.A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of (1) each of these decreases (2) copper strip increases and that of germanium decreases (3) copper strip decreases and that of germanium (4) each of these increases increases

Q55.The magnetic lines of force inside a bar magnet (1) are from north-pole to south-pole of the magnet (2) do not exist (3) depend upon the area of cross-section of the bar (4) are from south-pole to north-pole of the magnet magnet

Q56.Curie temperature is the temperature above which (1) a ferromagnetic material becomes paramagnetic (2) a paramagnetic material becomes diamagnetic (3) a ferromagnetic material becomes diamagnetic (4) a paramagnetic material becomes ferromagnetic

Q57.A particle of mass M and charge Q moving with velocity →v describe a circular path of radius R when subjected to a uniform transverse magnetic field of induction B. The work done by the field when the particle completes one full circle is (1) ( Mv2R )2πR (2) Zero (3) BQ2πR (4) BQ v 2πR

Q59.Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon (1) the rates at which currents are changing in the (2) relative position and orientation of the two coils two coils (3) the materials of the wires of the coils. (4) the currents in the two coils

Q62.The core of any transformer is laminated so as to (1) reduce the energy loss due to eddy currents (2) make it light weight (3) make it robust and strong (4) increase the secondary voltage

Q64.The image formed by an objective of a compound microscope is (1) virtual and diminished (2) real and diminished (3) real and enlarged (4) virtual and enlarged