CBSE Class 12 (Science) Moving Charges and Magnetism — practice questions
117 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice CBSE Class 12 (Science) Moving Charges and Magnetism in the app →A long straight wire carries $5$ A. The magnetic field $0.10$ m away from the wire is:The magnetic force on a charge $q$ moving with velocity $\vec{v}$ in a magnetic field $\vec{B}$ isA positive charge moves with velocity $\vec{v}$ PARALLEL to a uniform magnetic field $\vec{B}$. The magnetic fThe magnetic field at the CENTRE of a circular current loop of radius $R$ carrying current $I$ isInside a long solenoid carrying current $I$ with $n$ turns per unit length, the magnetic field isA current loop of area $A$ carrying current $I$ has a MAGNETIC MOMENT of magnitudeThe magnetic field at a distance $r$ from a LONG STRAIGHT wire carrying current $I$ isA charged particle moves with velocity v parallel to a uniform magnetic field B. The magnetic force on the parA circular loop of radius R carries current I. The magnitude of the magnetic field at its centre isThe angular frequency of a particle of charge q and mass m moving in a cyclotron with magnetic field B isTwo long parallel wires carry currents in the same direction. They willThe magnetic field inside an ideal long solenoid with n turns per unit length carrying current I isIn a crossed E and B velocity selector, a charged particle of speed v passes undeflected when v equalsA proton of mass m, charge e, speed v enters a magnetic field B perpendicular to its velocity. The radius of iA rectangular current loop is placed in a uniform magnetic field. The net force on the loop isA circular coil of N turns and radius R carries current I. Its magnetic dipole moment isThe magnitude of the magnetic field at perpendicular distance r from an infinite straight wire carrying currenThe magnetic field inside a toroidal solenoid with N total turns, mean radius r, carrying current I isThe period of revolution of a charged particle moving in a uniform magnetic field perpendicular to its velocitA 0.5 m wire carrying 2 A is placed perpendicular to a 0.4 T magnetic field. The force on the wire isTwo long parallel wires 0.1 m apart carry 5 A and 10 A in the same direction. The force per unit length on eacAt equilibrium, the deflection ϕ of a moving coil galvanometer with N turns, area A, current I, in a radial maAn electron enters a uniform magnetic field B at angle θ to B with speed v. The pitch of its helical path isA cyclotron of dee radius R accelerates ions of charge q, mass m in a magnetic field B. The maximum kinetic enA circular loop of radius R carries current I. The magnetic field at a point on its axis at distance x from thAt the very end of a long solenoid, the magnetic field along the axis isA magnetic dipole with moment m makes angle θ with a uniform field B. The torque on the dipole has magnitudeAn electron moves east in a magnetic field directed north. The magnetic force on the electron pointsA cyclotron operates at frequency f in a magnetic field B. The charge-to-mass ratio of the accelerated ion isThe current sensitivity of a moving coil galvanometer with N turns, coil area A, magnetic field B, spring consA 0.1 m radius loop carries 5 A. The magnetic field at a point on its axis 0.1 m from the centre is approximatA bar magnet with N pole pointing right is placed near a circular current loop whose magnetic moment also poinCyclotrons are not used to accelerate electrons becauseA long solenoid has 1000 turns per metre and carries 2 A. The magnetic field strength inside isA square coil of side 0.1 m, with 50 turns, carries 1 A in a 0.2 T field. The maximum torque on the coil isA charge q moves with velocity v through a region with electric field E and magnetic field B. The net electromThe force on a charge moving in electric and magnetic fields is named after:The magnetic force on a charge depends on its charge, its velocity and the:Compared with a positive charge, the force on a negative charge is:The magnetic force involves which product of velocity and field?To find the force on a current, the rod considered has uniform:With carrier density n, area A and length l, the number of carriers is:All known magnetic fields are due to moving charges and to intrinsic:The law giving the field of a current element is named after Biot and:By the Biot-Savart law, the field of a current element is proportional to the:The Biot-Savart field falls off with distance as its:The Biot-Savart field direction is perpendicular to the plane containing dl and:Ampere's circuital law is an alternative way of expressing the law of:Ampere's circuital law considers a surface that is:Ampere's law is to Biot-Savart law what Gauss's law is to the law of:Ampere's circuital law holds for loops that are:Ampere's law is easiest to apply in situations of high:The two pieces of equipment used to generate magnetic fields are the toroid and the:The machine that combines a solenoid and a toroid for high fields is the:A toroid is a hollow ring wound closely with many:A toroid can be viewed as a solenoid that has been:A galvanometer becomes an ammeter by adding a shunt resistance in:A galvanometer becomes a voltmeter by adding a large resistance in:Oersted's 1820 demonstration showed a current deflecting which object?In which year did Oersted observe a current deflecting a compass needle?Oersted concluded that a magnetic field is produced by what?Which physicist realised that light is an electromagnetic wave after unifying electricity and magnetism?A charge moving parallel to a magnetic field feels what magnetic force?In which direction does the magnetic force on a moving charge act?One gauss, the smaller non-SI unit of magnetic field, equals how many tesla?Which combination of units is equivalent to one tesla?A 0.5 m wire carrying 4 A is at 30° to a 0.2 T field. Force on it?An electron moves at 2 × 10^6 m/s perpendicular to a 0.5 T field. Force on it?Why does a magnetic field do no work on a moving charge?A charge moves perpendicular to a uniform magnetic field. What path results?If a charge's velocity has a component along B, its path isRadius of the circular path of charge q, mass m, speed v in field B isDoubling a charged particle's speed in a fixed field changes its orbit radius how?The frequency of circular motion of a charge in B is independent ofIf B doubles, how does the orbital frequency of a given charge change?What property of circular motion in B does a cyclotron exploit?The distance a helically moving charge advances along B in one rotation is called itsAn electron at 3 × 10^7 m/s moves perpendicular to a 6 × 10^-4 T field. Orbit radius?An electron moving at 3 × 10^7 m/s has a kinetic energy of aboutIn the Biot-Savart law, the magnitude of dB varies with distance r asThe Biot-Savart law gives the magnetic field due to which source?The Biot-Savart field dB at a point along the line of the current element isWhich relation links μ0, ε0 and the speed of light c?How do the Coulomb and Biot-Savart fields both depend on distance?The Biot-Savart field dB at point P points in which direction?A single loop of radius 10 cm carries 5 A. Field at its centre?A long straight wire carries 10 A. What is the field 5 cm from it?The field lines around a long straight current-carrying wire areAmpere's circuital law: loop integral of B equalsThe closed contour chosen when applying Ampere's law is called aIf the net current enclosed by an Amperian loop is zero, the line integral of B isThe field outside an ideal very long solenoid is taken to beInside a long solenoid the magnetic field isWhy are enamelled wires used to wind a solenoid?What does a soft iron core inside a solenoid do to the field?The equal and opposite forces on two parallel current-carrying wires agree withForce per unit length between parallel currents Ia and Ib a distance d apart isWires 0.1 m apart carry 10 A and 20 A in parallel. Force per metre?The ampere definition uses long parallel wires placed how far apart?Which instrument is used to measure the force between current-carrying coils in practice?One coulomb of charge crosses a conductor's section in 1 s at what current?A loop of area A carrying I has B in its plane. The torque isA 100-turn, 0.01 m^2 coil with 2 A lies in the plane of a 0.5 T field. Torque?The magnetic moment of a planar loop with N turns, current I, area A isA 50-turn coil of area 0.04 m^2 carries 0.2 A. Its magnetic moment?The torque on a magnetic moment m in a uniform field B isSeen from far away, a planar current loop is equivalent toOn the axis of a circular loop far away (x much greater than R), B varies asWhich isolated entity has never been observed, unlike electric charge?Ampere suggested that all magnetism arises fromA moving coil galvanometer gets its radial field usingIn a moving coil galvanometer, what balances the magnetic torque?The deflection of a moving coil galvanometer is proportional toHow is a galvanometer converted into an ammeter?A 100 ohm, 1 mA galvanometer becomes a 10 V voltmeter. Series resistance?Doubling the coil turns N in a galvanometer does what to current sensitivity?If the turns N in a galvanometer coil are doubled, voltage sensitivity