Practice Questions

Q26.A coil in the shape of an equilateral triangle of side 10 cm lies in a vertical plane between the pole pieces of permanent magnet producing a horizontal magnetic field 20 mT. The torque acting on the coil when a current of 0. 2 A is passed through it and its plane becomes parallel to the magnetic field will be √x × 10−5 Nm . The value of x is

Q26.In an electrical circuit, a battery is connected to pass 20 C of charge through it in a certain given time. The potential difference between two plates of the battery is maintained at 15 V . The workdone by the battery is _______ J

Q26.First, a set of n equal resistors of 10 Ω each are connected in series to a battery of E.M.F. 20 V and internal resistance 10 Ω. A current I is observed to flow. Then, the n resistors are connected in parallel to the same battery. It is observed that the current is increased 20 times, then the value of n is ___________.

Q26.The ratio of the equivalent resistance of the network (shown in figure) between the points a and b when switch is open and switch is closed is x : 8 . The value of x is JEE Main 2021 (27 Aug Shift 2) JEE Main Previous Year Paper

Q26.The amplitude of wave disturbance propagating in the positive x-direction is given by y = 1 at time t = 0 (1+x)2 and y = 1 at t = 1 s, where x and y are in metres. The shape of wave does not change during the 1+(x−2)2 propagation. The velocity of the wave will be m s−1.

Q26.A series LCR circuit of R = 5 Ω, L = 20 mH and C = 0. 5 μF is connected across an AC supply of 250 V , having variable frequency. The power dissipated at resonance condition is ________ ×102 W.

Q26.In 5 minutes , a body cools from 75 °C to 65 °C at room temperature of 25 °C. The temperature of body at the end of next 5 minutes is ∘C.

Q26.A resonance circuit having inductance and resistance 2 × 10-4 H and 6 . 28 Ω respectively oscillates at 10 MHz frequency. The value of quality factor of this resonator is_______. 𝜋= 3 . 14

Q26.A point charge of +12 μC is at a distance 6 cm vertically above the centre of a square of side 12 cm as shown in figure. The magnitude of the electric flux through the square will be _______ ×103 N m2 C−1. JEE Main 2021 (24 Feb Shift 2) JEE Main Previous Year Paper

Q26.The peak electric field produced by the radiation coming from the 8 W bulb at a distance of 10 m is x V m−1 . The efficiency of the bulb is 10% and it is a point source. The value of x is, 10 √μ0cπ

Q26.A uniform heating wire of resistance 36 Ω is connected across a potential difference of 240 V . The wire is then cut into half and a potential difference of 240 V is applied across each half separately. The ratio of power dissipation in first case to the total power dissipation in the second case would be 1: 𝑥, where 𝑥 is -1

Q26.A sinusoidal voltage of peak value 250 V is applied to a series LCR circuit, in which R = 8 Ω, L = 24 mH and C = 60 μF. The value of power dissipated at resonant condition is x kW . The value of x to the nearest integer is _______.

Q26.For an ideal heat engine, the temperature of the source is 127°C. In order to have 60% efficiency the temperature of the sink should be __________ ∘C. (Round off to the nearest integer)

Q26.Four identical rectangular plates with length, l = 2 cm and breadth, b = 32 cm are arranged as shown in figure. The equivalent capacitance between A and C is xε0d . The value of x is _______. (Round off to the Nearest Integer)

Q26.The electric field in a region is given by E = 5 E0ˆi + 5 E0ˆj field through a rectangular surface, area 0. 4 m2 parallel to the Y −Z plane is _______ N m2 C−1 .

Q26.A particle performs simple harmonic motion with a period of 2 second. The time taken by the particle to cover a displacement equal to half of its amplitude from the mean position is 1 s. The value of a to the nearest a integer is

Q26.An infinite number of point charges, each carrying 1 μC charge, are placed along the y-axis at y = 1 m, 2 m, 4 m, 8 m . . . . The total force on a 1 C point charge, placed at the origin, is x × 103 N . The value of x, to the nearest integer, is ___ . [Take 1 = 9 × 109 N m2 C−2 ] 4πϵ0

Q27.In Bohr's atomic model, the electron is assumed to revolve in a circular orbit of radius 0. 5 A. If the speed of electron is 2. 2 × 106 m s−1. Then the current associated with the electron will be__________ ×10−2 mA. [Take π as 22 7 ]

Q27.An AC circuit has an inductor and a resistor of resistance R in series, such that XL = 3R. Now, a capacitor is added in series such that XC = 2R. the ratio of the new power factor with the old power factor of the circuit is √5 : x. The value of x is

Q27.A uniform conducting wire of length is 24a, and resistance R is wound up as a current carrying coil in the shape of an equilateral triangle of side a and then in the form of a square of side a . The coil is connected to a voltage source V0. The ratio of magnetic moment of the coils in case of equilateral triangle to that for square is 1 : √y where y is ____________. + A . The R.M.S. value of this current is

Q27.A fringe width of 6 mm was produced for two slits separated by 1 mm apart. The screen is placed 10 m away. The wavelength of light used is x nm. The value of x to the nearest integer is ______.

Q27.The voltage drop across 15 Ω resistance in the given figure will be _______ V.

Q27.A steel rod with 𝑦= 2 . 0 × 1011 N m-2 and 𝛼= 10-5 ∘C of length 4 m and area of cross-section 10 cm2 is heated from 0°C to 400°C without being allowed to extend. The tension produced in the rod is JEE Main 2021 (01 Sep Shift 2) JEE Main Previous Year Paper 𝑥× 105 N where the value of 𝑥 is _________ .

Q27.Two short magnetic dipoles m1 and m2 each having magnetic moment of 1 A m2 are placed at point O and P respectively. The distance between OP is 1 m . The torque experienced by the magnetic dipole m2 due to the presence of m1 is ________ × 10−7N m

Q27.Consider a 72 cm long wire AB as shown in the figure. The galvanometer jockey is placed at P on AB at a distance x cm from A . The galvanometer shows zero deflection. JEE Main 2021 (18 Mar Shift 2) JEE Main Previous Year Paper The value of x, to the nearest integer, is