Practice Questions

Q45.If there are n capacitors in parallel connected to V volt source, then the energy stored is equal to (1) CV (2) 12 nCV2 (3) CV2 (4) 2n1 CV 2

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

Q48.A wire when connected to 220 V mains supply has power dissipation P1 . Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is P2 Then P2 : P1 is (1) 1 (2) 4 (3) 2 (4) 3

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

Q51. If in the circuit, power dissipation is 150 W, then R is (1) 2Ω (2) 6Ω (3) 5Ω (4) 4Ω JEE Main 2002 JEE Main Previous Year Paper

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

Q53.If an electron and a proton having same momenta enter perpendicular to a magnetic field, then (1) curved path of electron and proton will be same (2) they will move undeflected (ignoring the sense of revolution) (3) curved path of electron is more curved than that (4) path of proton is more curved of the proton

Q54.Wires 1 and 2 carrying currents i1 and i2 respectively are inclined at an angle θ to each other. What is the force on a small element dl of wire 2 at a distance of r from wire 1 (as shown in the figure) due to the magnetic field of wire 1 ? μ0 (1) θ 2πr i1i2dl tan θ (2) 2πrμ0 i1i2 dl sin (3) 2πr μ0 i1i2dl cos θ (4) 4πrμ0 i1i2dl sin θ

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

Q56.A conducting square loop of side L and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A magnetic induction B constant in time and space, pointing perpendicular and into the plane at the loop exists everywhere with half the loop outside the field, as shown in figure. The induced emf is (1) zero (2) RvB (3) VBL/R (4) VBL

Q57. The inductance between A and D is (1) 3.66 H (2) 9 H (3) 0.66 H (4) 1 H JEE Main 2002 JEE Main Previous Year Paper

Q58.The mass of product liberated on anode in an electrochemical cell depends on (where t is the time period, for which the current is passed) (1) (It)1/2 (2) IT (3) I/t (4) I2t

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

Q64.An astronomical telescope has a large aperture to (1) reduce spherical aberration (2) have high resolution (3) increase span of observation (4) have low dispersion

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

Q67.Wavelength of light used in an optical instrument are λ1 = 4000Å and λ2 = 5000Å, then ratio of their respective resolving powers (corresponding to λ1 and λ2 ) is (1) 16 : 25 (2) 9 : 1 (3) 4 : 5 (4) 5 : 4

Q68.Sodium and copper have work functions 2.3eV and 4.5eV respectively. Then the ratio of the wave lengths is nearest to JEE Main 2002 JEE Main Previous Year Paper (1) 1 : 2 (2) 4 : 1 (3) 2 : 1 (4) 1 : 4

Q69.Formation of covalent bonds in compounds exhibits (1) wave nature of electron (2) particle nature of electron (3) both wave and particle nature of electron (4) none of these