Practice Questions

Q14.A mass m attached to free end of a spring executes SHM with a period of 1 s. If the mass is increased by 3 kg the period of oscillation increases by one second, the value of mass m is ________ kg.

Q14.For the plane electromagnetic wave given by 𝐸= 𝐸0sin ( 𝜔𝑡– 𝑘𝑥) and 𝐵= 𝐵0sin ( 𝜔𝑡- 𝑘𝑥) , the ratio of average electric energy density to average magnetic energy density is 1 (1) (2) 2 2 (3) 4 (4) 1

Q14.The magnetic moments associated with two closely wound circular coils 𝐴 and 𝐵 of radius 𝑟𝐴= 10 cm and 𝑟𝐵= 20 cm respectively are equal if: (Where 𝑁𝐴, 𝐼𝐴 and 𝑁𝐵, 𝐼𝐵 are number of turn and current of 𝐴 and 𝐵 respectively) (1) 2𝑁𝐴𝐼𝐴= 𝑁𝐵𝐼𝐵 (2) 𝑁𝐴= 2𝑁𝐵 (3) 𝑁𝐴𝐼𝐴= 4𝑁𝐵𝐼𝐵 (4) 4𝑁𝐴𝐼𝐴= 𝑁𝐵𝐼𝐵

Q14.A rod with circular cross-section area 2 cm2 and length 40 cm is wound uniformly with 400 turns of an insulated wire. If a current of 0 . 4 A flows in the wire windings, the total magnetic flux produced inside windings is 4π × 10-6 Wb. The relative permeability of the rod is (Given : Permeability of vacuum μ0 = 4π × 10-7 N A-2) 32 (1) 12 . 5 (2) 5 (3) 125 (4) 5 16

Q15.Match List I with List II List I List II A Troposphere I Approximate 65 −75 km over Earth’s surface B E-Part of Stratosphere II Approximate 300 km over Earth’s surface C F2 -Part of Thermosphere III Approximate 10 km over Earth’s surface D D-Part of Stratosphere IV Approximate 100 km over Earth’s surface Choose the correct answer from the options given below : (1) A-III, B-IV, C-II, D-I (2) A-I, B-II, C-IV, D-III (3) A-I, B-IV, C-III, D-II (4) A-III, B-II, C-I, D-IV

Q15.Match the List-I with List-II: List I List II A Microwaves I Radioactive decay of the nucleus B Gamma rays II Rapid acceleration and deceleration of electron in aerials C Radio waves III Inner shell electrons D X-rays IV Klystron valve Choose the correct answer from the options given below: (1) A-I, B-II, C-III, D-IV (2) A-IV, B-I, C-II, D-III (3) A-I, B-III, C-IV, D-II (4) A-IV, B-III, C-II, D-I Q16.‘𝑛’ polarizing sheets are arranged such that each makes an angle 45° with the proceeding sheet. An 𝐼 unpolarized light of intensity 𝐼 is incident into this arrangement. The output intensity is found to be . The 64 value of 𝑛 will be: (1) 3 (2) 6 (3) 5 (4) 4

Q15.Electric potential at a point P due to a point charge of 5 × 10−9 C is 50 V . The distance of P from the point charge is: (Assume, 1 = 9 × 109 N m2 C−2 ) 4πε0 (1) 9 cm (2) 3 cm (3) 0. 9 cm (4) 90 cm

Q15.A point charge 2 × 10–2 C is moved from P to S in a uniform electric field of 30 N C–1 directed along positive x-axis. If coordinates of P and S are (1, 2, 0) m and (0, 0, 0) m respectively, the work done by electric field will be (1) 1200 mJ (2) 600 mJ (3) −600 mJ (4) −1200 mJ

Q16.Match List-I with List II of Electromagnetic waves with corresponding wavelength range: List I List II (A) Microwave (I) 400 nm to 1 nm (B) Ultraviolet (II) 1 nm to 10–3 nm (C) X -Ray (III) 1 mm to 700 nm (D) Infra-red (IV) 0. 1 m to 1 mm Choose the correct answer from the options given below: (1) (A) −(IV), (B) −(I), (C) −(II), (D) −(III) (2) (A) −(IV), (B) −(I), (C) −(III), (D) −(II) (3) (A) −(IV), (B) −(II), (C) −(I), (D) −(III) (4) (A) −(I), (B) −(IV), (C) −(II), (D) −(III)

Q16.In an electromagnetic wave, at an instant and at a particular position, the electric field is along the negative z- axis and magnetic field is along the positive x-axis. Then the direction of propagation of electromagnetic wave is: (1) positive z-axis (2) positive y-axis (3) at 45°angle from positive y -axis (4) negative y-axis

Q16.An object is placed at a distance of 12 cm in front of a plane mirror. The virtual and erect image is formed by the mirror. Now the mirror is moved by 4 cm towards the stationary object. The distance by which the position of image would be shifted, will be (1) 4 cm towards mirror (2) 8 cm towards mirror (3) 8 cm away from mirror (4) 2 cm towards mirror

Q17.The half life of a radioactive substance is 𝑇. The time taken, for disintegrating 7 𝑡ℎ part of its original mass will 8 be: (1) 2𝑇 (2) 3𝑇 (3) 𝑇 (4) 8𝑇

Q17.A small object at rest, absorbs a light pulse of power 20 mW and duration 300 ns. Assuming speed of light as 3 × 108 m s-1. The momentum of the object becomes equal to : (1) 0 . 5 × 10-17 kg m s-1 (2) 2 × 10-17 kg m s-1 (3) 3 × 10-17 kg m s-1 (4) 1 × 10-17 kg m s-1

Q17.Ratio of thermal energy released in two resistor R and 3R connected in parallel in an electric circuit is : (1) 3 : 1 (2) 1 : 1 (3) 1 : 3 (4) 1 : 27

Q17.The energy levels of an hydrogen atom are shown below. The transition corresponding to emission of shortest wavelength is JEE Main 2023 (06 Apr Shift 1) JEE Main Previous Year Paper (1) 𝐷 (2) 𝐴 (3) 𝐵 (4) 𝐶

Q17.A single slit of width a is illuminated by a monochromatic light of wavelength 600 nm . The value of a for which first minimum appears at θ = 30o on the screen will be : (1) 1. 2 μm (2) 3 μm (3) 1. 8 μm (4) 0. 6 μm

Q17.A metallic surface is illuminated with radiation of wavelength 𝜆, the stopping potential is 𝑉0. If the same 𝑉0 surface is illuminated with radiation of wavelength 2𝜆, the stopping potential becomes . The threshold 4 wavelength for this metallic surface will be (1) 3𝜆 (2) 4𝜆 (3) 3 (4) 𝜆 2𝜆 4

Q18.The de Broglie wavelength of an electron having kinetic energy E is λ . If the kinetic energy of electron becomes E , then its de-Broglie wavelength will be: 4 (1) √2λ (2) λ √2 (3) λ (4) 2λ 2

Q18.Speed of an electron in Bohr’s 7th orbit for Hydrogen atom is 3 . 6 × 106 m s-1. The corresponding speed of the electron in 3rd orbit, in m s-1 is : (1) 1 . 8 × 106 (2) 7 . 5 × 106 (3) 3 . 6 × 106 (4) 8 . 4 × 106

Q18.The H amount of thermal energy is developed by a resistor in 10 s when a current of 4 A is passed through it. If the current is increased to 16 A , the thermal energy developed by the resistor in 10 s will be (1) H (2) 16H (3) H (4) 4H 4

Q18.The angular momentum for the electron in Bohr’s orbit is 𝐿. If the electron is assumed to revolve in second orbit of hydrogen atom, then the change in angular momentum will be (1) Zero (2) 2𝐿 (3) 𝐿 (4) 𝐿 2

Q19.A massage signal of frequency 3 kHz is used to modulate a carrier signal of frequency 1 . 5 MHz. The bandwidth of the amplitude modulated wave is (1) 6 MHz (2) 6 kHz (3) 3 MHz (4) 3 kHz

Q19.The logic performed by the circuit shown in figure is equivalent to JEE Main 2023 (11 Apr Shift 1) JEE Main Previous Year Paper (1) AND (2) NOR (3) OR (4) NAND

Q20.The amplitude of 15sin ( 1000π𝑡) is modulated by 10sin ( 4π𝑡) signal. The amplitude modulated signal contains frequency (ies) of ( 𝐴) 500 Hz ( 𝐵) 2 Hz ( 𝐶) 250 Hz ( 𝐷) 498 Hz ( 𝐸) 502 Hz Choose the correct answer from the options given below: (1) A only (2) A, D and E only (3) B only (4) A and B only

Q20.To radiate EM signal of wavelength 𝜆 with high efficiency, the antennas should have a minimum size equal to: (1) 2𝜆 (2) 𝜆 2 (3) 𝜆 (4) 𝜆 4