Practice Questions

Q26.Resistance of a wire at 0∘C, 100∘C and t∘C is found to be 10Ω, 10.2Ω and 10.95Ω respectively. The temperature t in Kelvin scale is _________

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 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.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

Q26.The current in a conductor is expressed as 𝐼= 3𝑡2 + 4𝑡3, where 𝐼 is in Ampere and 𝑡 is in second. The amount of electric charge that flows through a section of the conductor during 𝑡= 1 s to 𝑡= 2 s is ____________ C .

Q26.Equivalent resistance of the following network is ________ 𝛺.

Q26.A heater is designed to operate with a power of 1000 W in a 100 V line. It is connected in combination with a resistance of 10Ω and a resistance R, to a 100 V mains as shown in figure. For the heater to operate at 62.5 W, the value of R should be _____ Ω.

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.A charge of 4. 0 μC is moving with a velocity of 4. 0 × 106 m s−1 along the positive y-axis under a magnetic field B of strength T. The force acting on the charge is xˆi N. The value of x is ______. (2ˆk)

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 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.A square loop of edge length 2 m carrying current of 2 A is placed with its edges parallel to the x y axis. A magnetic field is passing through the x −y plane and expressed as →B = B0(1 + 4x)^k, where B0 = 5 T. The net magnetic force experienced by the loop is _______ N .

Q27.Two long, straight wires carry equal currents in opposite directions as shown in figure. The separation between the wires is 5. 0 cm. The magnitude of the magnetic field at a point P midway between the wires is _____ μT . (Given: μ0 = 4π × 10−7 T m A−1 )

Q27.To determine the resistance (R) of a wire, a circuit is designed below. The V −I characteristic curve for this circuit is plotted for the voltmeter and the ammeter readings as shown in figure. The value of R is ______ Ω.

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.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)

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.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.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.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.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.A horizontal straight wire 5 m long extending from east to west falling freely at right angle to horizontal component of earth's magnetic field 0. 60 × 10−4 Wb m−2 . The instantaneous value of emf induced in the wire when its velocity is 10 m s−1 is _______ ×10−3 V . JEE Main 2024 (29 Jan Shift 2) JEE Main Previous Year Paper

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 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.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.