Practice Questions

Q21.The length of a metallic wire is increased by 20% and its area of cross-section is reduced by 4 % . The percentage change in resistance of the metallic wire is ________ .

Q21.For the given figures, choose the correct options: (1) The rms current in circuit (b) can never be larger (2) The rms current in figure (a) is always equal to than that in (a) that in figure (b) (3) The rms current in circuit (b) can be larger than (4) At resonance, current in (b) is less than that in (a) that in (a)

Q21.A small particle moves to position 5 ^𝑖- 2 ^𝑗+ ^𝑘 from its initial position 2 ^𝑖+ 3 ^𝑗- 4 ^𝑘 under the action of force 5 ^𝑖+ 2 ^𝑗+ 7 ^𝑘 N. The value of work done will be ______ J.

Q21.A charge particle moving in magnetic field B, has the components of velocity along B as well as perpendicular to B. The path of the charge particle will be (1) helical path with the axis perpendicular to the (2) helical path with the axis along magnetic field B direction of magnetic field B (3) circular path (4) straight along the direction of magnetic field B

Q21.An alternating voltage source V = 260 sin(628t) is connected across a pure inductor of 5 mH . Inductive reactance in the circuit is: (1) 3. 14Ω (2) 6. 28Ω (3) 0. 5Ω (4) 0. 318Ω

Q21.As shown in the figure, a long straight conductor with semicircular arc of radius π m is carrying current 10 I = 3A . The magnitude of the magnetic field. at the center O of the arc is: (The permeability of the vacuum = 4π × 10−7 NA−2 ) (1) 6 μT (2) 1 μT (3) 4 μT (4) 3 μT

Q22.In the given circuit, rms value of current (Irms) through the resistor R is : (1) 2 A (2) 21 A (3) 20 A (4) 2√2 A

Q22.An inductor of inductance 2 μH is connected in series with a resistance, a variable capacitor and an AC source of frequency 7 kHz. The value of capacitance for which maximum current is drawn into the circuit is x1 F , where the value of x is ______. (Take π = 227 )

Q22.Three identical resistors with resistance R = 12 Ω and two identical inductors with sell inductance L = 5 mH are connected to an ideal battery with emf of 12 V as shown in figure. The current through the battery long after the switch has been closed will be________ A. JEE Main 2023 (24 Jan Shift 2) JEE Main Previous Year Paper

Q22.If the earth suddenly shrinks to 1 of its original volume with its mass remaining the same, the period of 64th 24 rotation of earth becomes 𝑥ℎ. The value of 𝑥 is ________

Q22.A spherical body of mass 2 kg starting from rest acquires a kinetic energy of 10000 J at the end of 5th second. The force acted on the body is _____ N.

Q22.Given below are two statements: Statement I : When the frequency of an AC source in a series LCR circuit increases, the current in the circuit first increases, attains a maximum value and then decreases. Statement II : In a series LCR circuit, the value of power factor at resonance is one. In the light of given statements, choose the most appropriate answer from the options given below. (1) Statement I is incorrect but Statement II is true (2) Both Statement I and Statement II are false (3) Both Statement I and Statement II are true (4) Statement I is correct but Statement II is false

Q22.A series combination of resistor of resistance 100 Ω inductor of inductance 1 H and capacitor of capacitance 6. 25 μF is connected to an ac source. The quality factor of the circuit will be _____.

Q22.A particle of mass 10 g moves in a straight line with retardation 2𝑥, where 𝑥 is the displacement in SI units. 10 -𝑛 Its loss of kinetic energy for above displacement is J . The value of 𝑛 will be ________ . 𝑥

Q22.Which of the following are true? A. Speed of light in vacuum is dependent on the direction of propagation. B. Speed of light in a medium is independent of the wavelength of light. C. The speed of light is independent of the motion of the source. D. The speed of light in a medium is independent of intensity. Choose the correct answer from the question given below : (1) A and C only (2) B and D only (3) B and C only (4) C and D only

Q22.Two long parallel wires carrying currents 8 A and 15 A in opposite directions are placed at a distance of 7 cm from each other. A point P is at equidistant from both the wires such that the lines joining the point P to the wires are perpendicular to each other. The magnitude of magnetic field at P is ______ ×10−6 T. (Given: √2 = 1. 4 )

Q22.Which of the following Maxwell’s equation is valid for time varying conditions but not valid for static conditions: → → → → (1) (2) ∮ B ⋅ dl = μ0I ∮ E ⋅ dl = 0 −→ → → (3) ∮→D ⋅dA = Q (4) ∮ E ⋅dl = −∂ϕB∂t

Q22.A metallic cube of side 15 cm moving along y-axis at a uniform velocity of 2 m s−1 . In a region of uniform magnetic field of magnitude 0. 5 T directed along z- axis. In equilibrium the potential difference between the faces of higher and lower potential developed because of the motion through the field will be mV.

Q22.The magnetic intensity at the centre of a long current carrying solenoid is found to be 1. 6 × 103 A m−1 . If the number of turns is 8 per cm, then the current flowing through the solenoid is ______A.

Q22.A lift of mass 𝑀= 500 kg is descending with speed of 2 m s-1. Its supporting cable begins to slip thus allowing it to fall with a constant acceleration of 2 m s-2. The kinetic energy of the lift at the end of fall through to a distance of 6 m will be ______ kJ.

Q22.A square shaped coil of area 70 cm2 having 600 turns rotates in a magnetic field of 0. 4 Wb m–2 , about an axis which is parallel to one of the side of the coil and perpendicular to the direction of field. If the coil JEE Main 2023 (01 Feb Shift 2) JEE Main Previous Year Paper completes 500 revolution in a minute, the instantaneous emf when the plane of the coil is inclined at 60° with the field, will be ______ V. (Take π = 227 )

Q22.A thin uniform rod of length 2 m, cross sectional area 𝐴 and density 𝑑 is rotated about an axis passing through the centre and perpendicular to its length with angular velocity 𝜔. If value of 𝜔 in terms of its 𝛼𝐸 rotational kinetic energy 𝐸 is √ 𝐴𝑑, then the value of 𝛼 is ______.

Q22.An LCR series circuit of capacitance 62. 5 nF and resistance of 50 Ω, is connected to an A.C. source of frequency 2. 0 kHz . For maximum value of amplitude of current in circuit, the value of inductance is ____ mH . (Take π2 = 10)

Q22.Two concentric circular coils with radii 1 cm and 1000 cm and number of turns 10 and 200 respectively are placed coaxially with centers coinciding. The mutual inductance of this arrangement will be _____ ×10–8 H . (Take, π2 = 10 )

Q22.A solid cylinder is released from rest from the top of an inclined plane of inclination 30° and length 60 cm. If the cylinder rolls without slipping, its speed upon reaching the bottom of the inclined plane is ______ m s-1. (Given 𝑔= 10 m s-2)