Practice Questions

Q43.A charged particle q is placed at the centre O of cube of length L (A B C D E F G H). Another same charge q is placed at a distance L from O. Then the electric flux through ABCD is (1) q/4πϵ0L (2) zero (3) q/2πϵ0L (4) q/3πϵ0L

Q46.Capacitance (in F ) of a spherical conductor with radius 1 m is (1) 1.1 × 10−10 (2) 10−6 (3) 9 × 10−9 (4) 10−3

Q47.If an ammeter is to be used in place of a voltmeter, then we must connect with the ammeter a (1) low resistance in parallel (2) high resistance in parallel (3) high resistance in series (4) low resistance in series

Q49.If a current is passed through a spring then the spring will (1) expand (2) compress (3) insulator (4) none of these

Q50.By increasing the temperature, the specific resistance of a conductor and a semiconductor (1) increases for both (2) decreases for both (3) increases, decreases (4) decreases, increases

Q52.If in a circular coil A of radius R, current I is flowing and in another coil B of radius 2R a current 2l is flowing, then the ratio of the magnetic fields BA and BB , produced by them will be (1) 1 (2) 2 (3) 1/2 (4) 4

Q55.The time period of a charged particle undergoing a circular motion in a uniform magnetic field is independent of its (1) speed (2) mass (3) charge (4) magnetic induction

Q59.The power factor of an AC circuit having resistance (R) and inductance (L) connected in series and an angular velocity ω is (1) R/ωL (2) R/(R2 + ω2L2)1/2 (3) ωL/R (4) R/(R2 −ω2L2) 1/2

Q60.In a transformer, number of turns in the primary coil are 140 and that in the secondary coil are 280. If current in primary coil is 4 A, then that in the secondary coil is (1) 4 A (2) 2 A (3) 6 A (4) 10 A

Q61.Electromagnetic waves are transverse in nature is evident by (1) polarization (2) interference (3) reflection (4) diffraction

Q62.Infra red radiation is detected by (1) spectrometer (2) pyrometer (3) nanometer (4) photometer

Q63.Which of the following are not electromagnetic waves? (1) cosmic rays (2) gamma rays (3) β-rays (4) X- rays

Q65.If two mirrors are kept at 60∘ to each other, then the number of images formed by them is (1) 5 (2) 6 (3) 7 (4) 8

Q66.Which of the following is used in optical fibres ? (1) total internal reflection (2) scattering (3) diffraction (4) refraction

Q70.If 13.6eV energy is required to ionize the hydrogen atom, then the energy required to remove an electron from n = 2 is (1) 10.2eV (2) 0eV (3) 3.4eV (4) 6.8eV

Q72.If N0 is the original mass of the substance of half- life period t1/2 = 5 years, then the amount of substance left after 15 years is (1) N0/8 (2) N0/16 (3) N0/2 (4) N0/4

Q74.At absolute zero, Si acts as (1) non metal (2) metal (3) insulator (4) none of these

Q75.The energy band gap is maximum in (1) metals (2) superconductors (3) insulators (4) semiconductors

Q76.The part of a transistor which is most heavily doped to produce large number of majority carriers is (1) emmiter (2) base (3) collector (4) can be any of the above three

Q79.In a hydrogen atom, if energy of an electron in ground state is 13.6 eV, then that in the 2nd excited state is JEE Main 2002 JEE Main Previous Year Paper (1) 1.51 eV (2) 3.4 eV (3) 6.04 eV (4) 13.6 eV

Q82.In which of the folloiwng species the interatomic bond angle is 109∘28′? (1) NH3, (BF4)−1 (2) (NH4)+, BF3 (3) NH3, BF4 (4) (NH2)−1, BF3

Q88.If an endothermic reaction is non- spantaneous at freezing point of water and becomes feasible at its boiling point, then (1) ΔH is - ve, ΔS is + ve (2) ΔH and ΔS both are + ve (3) ΔH and ΔS both are − ve (4) ΔH is + ve, ΔS is −ve

Q91.Change in volume of the system does not alter the number of moles in which of the following equilibria ? (1) N2( g) + O2( g) ⇌2NO(g) (2) PCl5( g) ⇌PCl3( g) + Cl2( g) (3) N2( g) + 3H2( g) ⇌2NH3( g) (4) SO2Cl2( g) ⇌SO2( g) + Cl2( g)