Practice Questions

Q26.The charge accumulated on the capacitor connected in the following circuit is ______ μC. (Given C = 150 μF)

Q26.A 16 Ω wire is bend to form a square loop. A 9 V battery with internal resistance 1 Ω is connected across one of its sides. If a 4 μF capacitor is connected across one of its diagonals, the energy stored by the capacitor will be x 2 μJ, where x =______.

Q26.Two cells are connected in opposition as shown. Cell E1 is of 8 V emf and 2 Ω internal resistance; the cell E2 is of 2 V emf and 4 Ω internal resistance. The terminal potential difference of cell E2 is ______ V .

Q26.Two charges of -4 μC and +4 μC are placed at the points 𝐴( 1, 0, 4 ) m and 𝐵( 2, - 1, 5 ) m located in an electric field →𝐸= 0 . 20 ^i V cm-1. The magnitude of the torque acting on the dipole is 8√𝛼× 10-5 N m, where 𝛼= _________.

Q26.Two wires A and B are made up of the same material and have the same mass. Wire A has radius of 2.0 mm and wire B has radius of 4.0 mm. The resistance of wire B is 2Ω. The resistance of wire A is _____ Ω. JEE Main 2024 (04 Apr Shift 2) JEE Main Previous Year Paper

Q26.A wire of resistance 20Ω is divided into 10 equal parts, resulting pairs. A combination of two parts are connected in parallel and so on. Now resulting pairs of parallel combination are connected in series. The equivalent resistance of final combination is _____ Ω.

Q26.In the given figure an ammeter A consists of a 240Ω coil connected in parallel to a 10Ω shunt. The reading of the ammeter is mA

Q27.A ceiling fan having 3 blades of length 80 cm each is rotating with an angular velocity of 1200 rpm. The magnetic field of earth in that region is 0. 5 G and angle of dip is 30°. The emf induced across the blades is Nπ × 10−5 V . The value of N is _______.

Q27.A solenoid of length 0.5 m has a radius of 1 cm and is made up of ' m ' number of turns. It carries a current of 5 A . If the magnitude of the magnetic field inside the solenoid is 6.28 × 10−3 T then the value of m is _____.

Q27.The coercivity of a magnet is 5 × 103 A/m . The amount of current required to be passed in a solenoid of length 30 cm and the number of turns 150 , so that the magnet gets demagnetised when inside the solenoid is _____A.

Q27.The magnetic field existing in a region is given by →B = 0.2(1 + 2x)^k T. A square loop of edge 50 cm carrying 0.5 A current is placed in x −y plane with its edges parallel to the x −y axes, as shown in figure. The magnitude of the net magnetic force experienced by the loop is_____ mN .

Q27.An electron moves through a uniform magnetic field →𝐵= 𝐵0 ^i + 2𝐵0 ^j T. At a particular instant of time, the → velocity of electron is →𝑢= 3 ^i + 5 ^j m s-1. If the magnetic force acting on electron is 𝐹= 5𝑒 ^k N, where 𝑒 is the charge of electron, then the value of 𝐵0 is ____ T.

Q27.Two resistance of 100𝛺 and 200𝛺 are connected in series with a battery of 4 V and negligible internal resistance. A voltmeter is used to measure voltage across 100𝛺 resistance, which gives reading as 1 V. The resistance of voltmeter must be _______ 𝛺. JEE Main 2024 (30 Jan Shift 2) JEE Main Previous Year Paper

Q27.The magnetic potential due to a magnetic dipole at a point on its axis situated at a distance of 20 cm from its center is 1. 5 × 10−5 T m . The magnetic moment of the dipole is _______ A m2 . (Given : μ0 = 10−7 T m A−1 ) 4π

Q27.A regular polygon of 6 sides is formed by bending a wire of length 4 π meter. If an electric current of 4𝜋√3 A is flowing through the sides of the polygon, the magnetic field at the centre of the polygon would be 𝑥× 10-7 T . The value of 𝑥 is ______.

Q27.Two circular coils 𝑃 and 𝑄 of 100 turns each have same radius of 𝜋 cm. The currents in 𝑃 and 𝑅 are 1 A and 2 A respectively. 𝑃 and 𝑄 are placed with their planes mutually perpendicular with their centers coincide. The resultant magnetic field induction at the center of the coils is √𝑥 mT, where 𝑥= ______. [Use 𝜇0 = 4𝜋× 10−7 T m A−1]

Q27.A coil having 100 turns, area of 5 × 10−3 m2 , carrying current of 1 mA is placed in uniform magnetic field of 0.20 T such a way that plane of coil is perpendicular to the magnetic field. The work done in turning the coil through 90∘ is _______ μJ.

Q27.A circular coil having 200 turns, 2.5 × 10−4 m2 area and carrying 100μA current→ is placed in a uniform magnetic field of 1T. Initially the magnetic dipole moment (M) was directed along →B. Amount of work, required to rotate the coil through 90∘ from its initial orientation such that M becomes perpendicular to →B, is ______ μJ.

Q27.The magnetic field at the centre of a wire loop formed by two semicircular wires of radii 𝑅1 = 2𝜋 m and 𝑅2 = 4𝜋 m carrying current 𝐼= 4 A as per figure given below is 𝛼× 10-7 T. The value of 𝛼 is _____. (Centre O is common for all segments) JEE Main 2024 (27 Jan Shift 2) JEE Main Previous Year Paper

Q27.A 2 A current carrying straight metal wire of resistance 1Ω, resistivity 2 × 10−6Ωm , area of cross-section 10 mm2 and mass 500 g is suspended horizontally in mid air by applying a uniform magnetic field →B . The magnitude of B is _____ ×10−1 T (given, g = 10 m/s2 ). JEE Main 2024 (05 Apr Shift 1) JEE Main Previous Year Paper

Q27.Two parallel long current carrying wire separated by a distance 2r are shown in the figure. The ratio of magnetic field at A to the magnetic field produced at C is x . The value of x is _____ 7

Q27.A moving coil galvanometer has 100 turns and each turn has an area of 2 . 0 cm2 . The magnetic field produced by the magnet is 0 . 01 T and the deflection in the coil is 0 . 05 radian when a current of 10 mA is JEE Main 2024 (01 Feb Shift 2) JEE Main Previous Year Paper passed through it. The torsional constant of the suspension wire is 𝑥× 10-5 N - m / rad . The value of 𝑥 is ______ .

Q27.An electron with kinetic energy 5eV enters a region of uniform magnetic field of 3 μT perpendicular to its direction. An electric field E is applied perpendicular to the direction of velocity and magnetic field. The value of E , so that electron moves along the same path, is _______ NC−1 . ( Given, mass of electron = 9 × 10−31 kg , electric charge = 1.6 × 10−19C)

Q28.For a given series LCR circuit it is found that maximum current is drawn when value of variable capacitance is 25nF. If resistance of 200Ω and 100mH inductor is being used in the given circuit. The frequency of ac source is ______ ×103 Hz . (given π2 = 10 )

Q28.A straight magnetic strip has a magnetic moment of 44Am2 . If the strip is bent in a semicircular shape, its magnetic moment will be _______ Am2 . (given π = 227 )