Practice Test

Q1) Current is passed through a straight wire. The magnetic field established around it has its lines of force: Show Answer

Q2) There are two parallel wires attracting each other when same current is passed through them in the same direction, they are brought closer, the force of attraction shall : Show Answer

Q3) A certain length of wire carrying current is bent in the form of a coil of one turn. The same wire is then bent to form two turns of smaller radius. the magnetic induction at its center for the same current is : Show Answer

Q4) Two identical coils carrying same current have common center but have their planes at right angles to each other. If the field due to each is B, what is the resultant field ? Show Answer

Q5) A straight conductor is split into identical semi-circular turns by tearing it into two parts from within. A current enters at one end and after passing through two parts leaves at the other. The field at the center of the loop of radius r is : Show Answer

Q6) A straight wire carrying current and placed in the field experiences maximum force if : Show Answer

Q7) Particles carrying positive charge travel from sky towards earth. On entering the earth's field they get deflected towards : Show Answer

Q8) A uniform electric field and a uniform magnetic field are produced pointing in the same direction. An electron projected with a velocity pointing in the same direction will : Show Answer

Q9) A wire with current directed towards east is placed in magnetic field directed north, the force on the wire is : Show Answer

Q10) A magnetic needle is put in a non-uniform magnetic field it will experience : Show Answer

Q11) If a proton is projected perpendicular to the field with velocity v and an electron is projected along the field, which of the following holds ? Show Answer

Q12) A galvanometer having resistance of 20 ohm and capable of carrying a maximum current of 40 mA is to be converted into an ammeter of range 0-5 A, the galvanometer is to be converted into a voltmeter of range 5 volt, what is the resistance needed ? Show Answer

Q13) A moving charge would produce : Show Answer

Q14) Two circular loops of equal radii are placed, one vertically and other horizontally with a common center. The current flowing is clockwise in both and has same magnitude. The direction of magnitude field at the center: Show Answer

Q15) Magnetic induction in a long straight wire is : Show Answer

Q16) A wire of a given length is first bent in one loop and then in three loops. If the same current is passed in the both cases, the ratio of magnetic field induction at the centers will be : Show Answer

Q17) A strong magnetic field is applied on a stationary electron, then : Show Answer

Q18) The no. of turns and radius of cross-section of the coil are doubled. If the current remains the same, the magnetic field at the center of the coil is : Show Answer

Q19) Two circular coil of wire carrying currents and of radii 20 cm and 40 cm are connected in parallel. The ratio of the magnetic fields at their centers is : Show Answer

Q20) The magnetic field at the center of a square loops of side L carrying a current I is : Show Answer

Q21) Magnetic induction due to long straight wire carrying current at a point on the wire itself is : Show Answer

Q22) If a long hollow copper pipe carries a direct current, the magnetic field associated with current will be : Show Answer

Q23) A current of 10 A is established in a long wire along the positive z-axis. The magnetic field at the point (1, 0, 0) meter is : Show Answer

Q24) P is a point mid-way between two infinite thin wires carrying current as shown, the net field at the point P is : Show Answer

Q25) Two long straight horizontal parallel wires, one above the other are separated by a distance 2a. If the wires carry equal currents in opposite direction, the magnitude of the field at a middle point between them is : Show Answer

Q26) A circular loop of radius R carrying a current I is placed in a uniform magnetic field with its plane perpendicular to B.The force on the loop is : Show Answer

Q27) A circular loop of radius R carrying a current I is placed in a uniform magnetic field with its plane perpendicular to B.The torque on the loop is : Show Answer

Q28) Weber ampere per meter is equal to : Show Answer

Q29) A moving coil voltmeter is generally used in the laboratory to measure the potential difference across a conductor of resistance r carrying current I. Voltmeter has resistance R and will measure the potential difference more correctly as : Show Answer

Q30) Fig. shows two long conducting wires placed at right angles. then carry currents as indicated. Assumes that 1A current in a long wire produces magnetic field B at a distance d from the wire. Then strength and direction of the field at the point X marked in the Fig. will be : Show Answer

Q31) No force is exerted by a magnetic field on Show Answer

Q32) What is the magnetic field in the empty space enclosed by toroidal solenoid of radius R ? Show Answer

Q33) Magnetic field due to a current carrying toroidal solenoid is independent of : Show Answer

Q34) A very long solenoid has 800 turns per meter length of the solenoid. A current of 1.6 ampere flows through it. Then, magnetic induction at the end of the solenoid on its axis is : Show Answer

Q35) A particle of charge q and mass m moving with a velocity v along the x-axis enters the region x > 0 with uniform magnetic field B along the z-direction. the particle will penetrate in this region in the x-direction upto a distance d equal to : Show Answer

Q36) Two parallel beams of electrons moving in the same direction, produce a mutual force of : Show Answer

Q37) A electron is shot into a liquid placed in a uniform magnetic field, in a plane perpendicular to the magnetic field. Then : Show Answer

Q38) A hollow tube is carrying an electric current along its length distributed uniformly over its surface. The magnetic field : Show Answer

Q39) Two ions have equal masses but one is singly ionized and the other is doubly ionized. They are projected from the same place in a uniform magnetic field with same velocity perpendicular to the field. Show Answer

Q40) A charged particle is projected into a uniform magnetic field with velocity perpendicular to direction of the field. which of the following quantities of particle will not change ? Show Answer

Q41) The magnetic induction at a point O, distance r from the corner of an infinitely long wire carrying current I and bent at right angle is : Show Answer

Q42) Two particles each of mass m and charge q are attached to the two ends of a light rod of length 2R. The rod is rotated at the constant angular speed about a perpendicular axis passing through its center. The radio of the magnitude of the magnetic moment of the system and its angular momentum about the center of the rod is : Show Answer

Q43) A long metal cylinder of radius r has a current I flowing through it. The magnetic induction B will vary with distance from the center as shown in : Show Answer

Q44) A long hollow metal cylinder of radius R has a current I flowing through it. The magnetic induction B will vary with distance from the center as shown in : Show Answer

Q45) A charge moves in a circle perpendicular to a magnetic field. The time period of revolution is independent of : Show Answer

Q46) An electron moves in a circular orbit with a uniform speed v. It produces a magnetic field of B at the center of the circle. The radius of the circle is proportional to : Show Answer

Q47) Which of the following graphs correctly represents the variation of energy density u near the mid-point of a long current carrying conductor with magnetic field B ? Show Answer

Q48) A charged particle is released from rest in a region of steady and uniform electric and magnetic field which are parallel to each other. The particle will move in a : Show Answer

Q49) An electron is moving along positive x-axis. To get it moving on an anti-clockwise circular path in x-y plane, a magnetic field is applied : Show Answer

Q50) A conductor of length 1 m carrying a current of 1 A is placed parallel to magnetic field 1 gauss. The magnetic force acting on the conductor is : Show Answer

Q51) A current - carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend upon : Show Answer

Q52) Two identical long solenoids carry the same constant current. When they are very far apart, the flux density at the center of each end of each solenoid is B. The solenoids are now arranged coaxially end to end with the current in each flowing in the same sense. The flux density on the axis in the region of contact is : Show Answer

Q53) A current carrying straight wire is kept along the axis of a circular loop carrying a current. The straight wire : Show Answer

Q54) Which of the following particles will experience maximum magnetic force ( magnetic ) when projected with the same velocity perpendicular to a magnetic field ? Show Answer

Q55) A charged particle is situated in a region of space and it experiences a force only when it is in motion. It can be deduced that the region encloses : Show Answer

Q56) An electric current I enters and leaves a uniform circular wire radius a through diametrically opposite points. A charged particle q moving along the axis of a circular wire passes through its center at speed v. The magnetic force acting on the particle when it passes through the center has a magnitude : Show Answer

Q57) A proton beam is going from north to south and an electron beam is going from south to north. Neglecting the earth's magnetic field, the electron beam will be deflected : Show Answer

Q58) The material used for the suspension wire of moving coil galvanometer is : Show Answer

Q59) A rectangular coil of area A of N turns has a current I flowing in clockwise direction when looked at from above. The magnetic moment associated with it : Show Answer

Q60) To measure total charge displaced through its terminals, we use : Show Answer

Q61) A current is flowing north along a power line. The direction of magnetic field above it, neglecting the earth's field is : Show Answer

Q62) Two long thin wires distant a apart exert a force F on one another when current through each wire is I. The distance between the wires is doubled and the current is decreased to I/3. The force they exert on another, now is : Show Answer

Q63) The pole pieces of the magnetic field whose direction is perpendicular to the velocity of the electron. Then : Show Answer

Q64) A current carrying small loop behaves like a small magnet. If A be its area and M its magnetic moment, the current in the loop will be : Show Answer

Q65) A circular loop carrying a current is replaced by an equivalent magnetic dipole. A point on the axis of the loop is now on : Show Answer

Q66) Two wires of equal length are placed perpendicular to the plane of paper at a distance of 5 cm from each other. If the currents flowing in first and second wires are 2A and 5A respectively in opposite directions, then the resultant magnetic field at mid-point of both the wires is : Show Answer

Q67) A length L of wire carries a steady current I. It is bent first to form a circular plane coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the center caused by the same current is : Show Answer

Q68) A current of 10 ampere is flowing in a wire of length 1.5 m. A force of 15 newton acts on it when it is placed in a uniform magnetic field of 12 tesla. The angle between the magnetic field and the direction of the current is : Show Answer

Q69) An ionized gas contains both positive and negative ions. If it is subjected simultaneously to an electric field along the +x direction and a magnetic field along the +z direction, then : Show Answer

Q70) Two long parallel wires are at a distance 2d apart. They carry steady equal currents flowing out of the plane of the paper, as shown in fig. The variation of the magnetic field B along the line XX' is given by : Show Answer

Q71) Two long parallel wires at distance d apart carry currents of 1 A and 3 A in the same direction. The wire carrying 1 A current lies to the left of the other wire. The points at which their magnetic fields cancel are located at : Show Answer

Q72) Cyclotron is used to accelerate : Show Answer

Q73) A closely wound flat circular coil of 25 turns of wire has diameter of 10 cm and carries a current of 4 ampere. Determine the flux density at the center of coil. Show Answer

Q74) A long vertical wire in which a current produces a neutral point with the earth's magnetic field at a distance of 5 cm from the wire. If the horizontal component of the earth's magnetic induction is 0.18 gauss, then the current in the wire is : Show Answer

Q75) A coil having N turns in wound tightly in the form of a spiral with inner and outer radii a and b respectively. When a current I passes through the coil, the magnetic field at the center is : Show Answer

Q76) Neutrons enter a magnetic field B in different directions with the same speed v. Which of the following statements is true ? Show Answer

Q77) The magnetic field of a certain length of wire for single turn coil at its center is B. Its value for two turns coil for the same wire is : Show Answer

Q78) A charged particle moves in a circular path in a uniform magnetic field. The radius of circular path is R. When energy of particle is doubled, then new radius will be : Show Answer

Q79) A particle of mass m and charge q moves with a constant velocity v along the positive x direction. It enters a region containing a uniform magnetic field B directed along the negative z direction, extending from x=a to x =b. The minimum value of v required so that the particle can just enter the region x > b is : Show Answer

Q80) An electron is travelling along the x-direction. It is encounters a magnetic field in the y-direction. Its subsequent motion will be : Show Answer

Q81) When a charged particle moves perpendicular to a magnetic field, then : Show Answer

Q82) A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, then new value of the magnetic field is : Show Answer

Q83) A wire of certain length carries a steady current. It is first bent to form a circular coil of one turn. The same wire is next bent to form a circular coil of three turns. The ratio of magnetic inductions at the center of the coil in the two cases is : Show Answer

Q84) The magnetic field (B) due to straight conductor of uniform cross-section of radius (a) and carrying a steady current (I) is represented by : Show Answer

Q85) Two parallel beams of positions moving in the same direction will : Show Answer

Q86) A circular coil of radius R carries an electric current. The magnetic field due to the coil at a point on the axis of the coil located at a distance r from center of the coil, such that r > > R varies : Show Answer

Q87) The magnetic moment of a current (I) carrying circular coil of radius (r) and number of turns (n) varies as : Show Answer

Q88) The cyclotron frequency of an electron gyrating in a magnetic field of 1 T is : Show Answer

Q89) A circular radius 'a' carries a current I. The magnetic induction at its center O due to the current is B. The distance from O of a point on the axis where the induction is B/8 is : Show Answer

Q90) The straight of the magnetic field at a point r near a long straight current carrying wire is B. The field at a distance r/2 will be : Show Answer

Q91) Electron of mass m and charge e is travelling with a speed v along the circular path of radius r at right angles of a uniform magnetic field B. If the speed of the electron is doubled and the magnetic field is halved the resulting path would have a radius : Show Answer

Q92) A particle having charge 'q' enters a magnetic field perpendicular to it, then which of the following is true ? Show Answer

Q93) A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a small distance and another point Q lies to the west at the same distance. The magnetic field at P is : Show Answer

Q94) Two circular coils 1 and 2 are made from the same wire but radius of 1st coil is twice that of 2nd coil. What potential difference in volts should be applied across them so that the magnetic field at their centers is same ? Show Answer

Q95) A beam of electrons passes undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off, and the same magnetic field is maintained, the electrons move Show Answer

Q96) Under the influence of a uniform magnetic field a charged particle is moving in a circle of radius R with constant speed V. The time period of the motion : Show Answer

Q97) A plate of iron oscillates first in a region having a magnetic field and then in a region with no field : Show Answer

Q98) A circular coil carrying a current is placed in a magnetic field. The torque on the coil will be one-half in maximum value, when the normal to the coil is : Show Answer

Q99) Reluctance of the circuit is Show Answer

Q100) In which of the situations given below will no force be experienced ? Show Answer

Q101) A beam of proton is directed along the negative direction of X-axis in a magnetic field along the +ve direction of Y-axis in XY plane. It will get deflected along : Show Answer

Q102) The moving galvanometer can be made more sensitive : Show Answer

Q103) A current I flows along the length of an infinitely long straight thin walled pipe. then Show Answer

Q104) An electron and a proton enter a magnetic field perpendicularly. Both have same kinetic energy. Which of the following is true ? Show Answer

Q105) In order to convert a milliametter of range 1.0 mA and resistance 1.0 ohm into a voltmeter of range 10V, a resistance of how many ohm should be connected with it and in what manner ? Show Answer