Magnetic Effects Of Current MCQ Level - 1 - Class 12 MCQ

A wire is wound on a long rod of material of relativepermeability μ_r = 4000 to make a solenoid. If the currentthrough the wire is 5 A and number of turns per unitlength is 1000 per metre, then the magnetic field insidethe solenoid is :

The magnetic field at the point of intersection of diagonals of a square loop of side L carrying a current I is

Two particles X and Y having equal charges, afterbeing accelerated through the same potential difference, enter a region of uniform magnetic fieldand describe circular path of radii R₁ and R₂ respectively. The ratio of mass of X to the mass Y is

Two identical coils carry equal currents and have acommon centre, but their planes are at right anglesto each other. What is the magnitude of the resultantmagnetic field at the centre if the field due to one coilalone is B?

A coaxial cable is made up of two conductors. Theinner conductor is solid and is of radius R₁ & theouter conductor is hollow of inner radius R₂ and outerradius R₃. The space between the conductors is filledwith air. The inner and outer conductors are carryingcurrents of equal magnitudes and in oppositedirections. Then the variation of magnetic field withdistance from the axis is best plotted as:

Three long, straight and parallel wires C, D and Gcarrying currents are arranged as shown in the figure.The force experienced by a 25 cm length of wire C is

A potential difference of 600 V is applied across theplates of a parallel plate capacitor. The separationbetween the plates is 3 mm. An electron projectedvertically, parallel to the plates, with a velocity of 2× 10⁶ ms^–1 moves undeflected between the plates.What is the magnitude of the magnetic field betweenthe capacitor plates?

Two particles each of mass m are charged q, areattached to the two ends of a light rigid rod of length 2l. The rod is rotated at a constant angular speed abouta perpendicular axis passing through its centre. Theratio of the magnitudes of the magnetic moment ofthe system and its angular momentum about the centreof the rod is

Axis of a solid cylinder of infinite length and radius R lies along y-axis it carries a uniformlydistributed current ‘ i ’ along  +y direction. Magnetic fieldat a point is :-

Two very long straight parallel wires carry steadycurrents I and –I. The distance between the wires isd. At a certain instant of time, a point charge q is at apoint equidistant from the two wires, in the plane ofthe wires. Its instantaneous velocity v is perpendicularto this plane. The magnitude of the force due to themagnetic field acting on the charge at this instant is

A rectangular loop carrying a current i is situated neara long straight wire such that the wire is parallel tothe one of the sides of the loop and is in the plane ofthe loop. If a steady current I is established in wireas shown in figure, the loop will

A steady current I flows in a small square loop ofwire of side L in a horizontal plane. The loop is nowfolded about its middle such that half of it lies in avertical plane. Let μ₁ and μ₂ respectively denote themagnetic moments due to the current loop before andafter folding. Then

A cylindrical wire of radius R is carrying current iuniformly distributed over its cross-section. If a circular loop of radius ' r ' is taken as amperican loop,then the variation value of  over this loop withradius ' r ' of loop will be best represented by:

An insulating rod of length L carries a charge Qdistributed uniformly on it. The rod is pivoted at one end and is rotated at a frequency f and about a fixed perpendicular axis. The magnetic dipole moment of the system is

A wire of resistance R in the form of a semicircle lieson the top of a smooth table. A uniform magnetic field B is confined to the region as shown. The ends of the semicircle are attached to springs C and D whose other ends are fixed. If r is the radius of the semicircle and k is the force constant for each spring, then the extension x in each spring is 

A circular current loop of radius a is placed in ara dial field B as shown. The net force acting on the loop is 

Two parallel, long wires carry currents i₁ and i₂ with i₁ >i₂. When the current are in the same direction, the magnetic field at a point midway between the wire is10mT. If the direction of i₂ is reversed, the field becomes 30μT. The ratio i₁/i₂ is

A positively charged particle projected towards east isdeflected towards north by a magnetic field. The fieldmay be

Which of the following particles will describe the smallestcircle when projected with the same velocity perpendicularto a magnetic field?

An electric current i enters and leaves a uniform circularwire of radius a through diametrically opposite points.A charged particle q moving along the axis of the circularwire passes through its centre at speed u. The magneticforce acting on the particle when it passes throughthe centre has a magnitude

A negative charged particle falling freely under gravityenters a region having uniform horizontal magnetic field pointing towards north. The particle willbe deflected towards

A proton of mass m and charge q enters a magneticfield B with a velocity v at an angle q with the directionof B. The radius of the resulting path is