Moving Charges & Magnetism PYQs Set 19 (PDF)

Set 19 of 19 · Questions 541-549 of 549

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Mere Teacher · Previous Year Questions JEE Main Physics · Moving Charges & Magnetism · Set 19 (Q541-549)
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541. $A rigid wire consists of a semicircular portion of radius R and two straight sections. The wire is partially immerged in a perpendicular magnetic field B = B_{0} j as shown in figure. The magnetic force on the wire if it has a current i is:$ (1) $- iBR j$ (2) $2 iBR j$ (3) $iBR j$ (4) $- 2 iBR j$ 542. $A current carrying rectangular loop PQRS is made of uniform wire. The length PR = QS = 5 cm and PQ = RS = 100 cm. If ammeter current reading changes from I to 2I, the ratio of magnetic forces per unit length on the wire PQ due to wire RS in the two cases respectively f_{PQ}^{I} : f_{PQ}^{2 I} is:$ (1) $1 : 2$ (2) $1 :4$ (3) $1 : 5$ (4) $1 : 3$ 543. $If number of turns, area and current through a coil is given by n, A and i respectively then its magnetic moment will be$ (1) $niA$ (2) $n^{2} iA$ (3) $ni A^{2}$ (4) $\frac{ni}{A}$ 544. $Given below are two statements: Statement (I): When currents vary with time, Newton's third law is valid only if momentum carried by the electromagnetic field is taken into account. Statement (II) : Ampere's circuital law does not depend on Biot-Savart's law. In the light of the above statements, choose the correct answer from the options given below:$ (1) $Both Statement I and Statement II are true$ (2) $Statement I is true but Statement II is false$ (3) $Both Statement I and Statement II are false$ (4) $Statement I is false but Statement II is true$ 545. $An infinitely long wire carrying 1 A current in the + Z direction is placed at (1 cm, 1 cm) . Another wire carrying 1 A in + x direction is placed at y = 1 cm . If the magnetic field due to this configuration at the origin is B . Let B_{0} be the magnitude of the field if only the wire at (1 cm, 1 cm) was present, then \frac{B}{B _{0}} is$ (1) $(\frac{1}{2}, - \frac{1}{2}, - 2)$ (2) $(\frac{1}{2}, \frac{1}{2}, - 1)$ (3) $(2, 2, - 2)$ (4) $(\frac{1}{2 2}, \frac{1}{2 2}, - \frac{1}{2})$ 546. $An observer at rest experiences an electric field due to a static charge. Later he starts moving away from it then the observer experiences.$ (1) $Only magnetic field$ (2) $Only electric field$ (3) $Electric and magnetic field$ (4) $No field at all$ 547. $The magnetic field due to current carrying circular loop of radius 6 cm at a point on the axis at a distance of 8 cm from centre is 27 μT . The magnetic field at the centre of the current carrying loop is.$ (1) $75 μT$ (2) $125 μT$ (3) $150 μT$ (4) $250 μT$ 548. $Tesla is the unit of$ (1) $electric field$ (2) $magnetic field$ (3) $electric flux$ (4) $magnetic flux.$ 549. $Tangent galvanometer is used to measure$ (1) $potential difference$ (2) $current$ (3) $resistance$ (4) $charge.$