Q.1
A long straight wire of radius a carries a steadycurrent I. The current is uniformly distributed overits cross-section. The ratio of the magnetic fieldsB and B', at radial distancesa/2and 2a respectively,from the axis of the wire is : … [AIPMT 2015]
  • a) 1/4
  • b) 1/2
  • c) 1
  • d) 4
Q.2
A long wire carrying a steady current is bent intoa circular loop of one turn. The magnetic field atthe centre of the loop is B. It is then bent into acircular coil of n turns. The magnetic field at thecentre of this coil of n turns will be … [NEET II 2016]
  • a) 2nB
  • b) 2n2B
  • c) nB
  • d) n2B
Q.3
An arrangement of three parallel straight wiresplaced perpendicular to plane of paper carrying samecurrent ‘I’ along the same direction is shown in Fig.Magnitude of force per unit length on the middle wire‘B’ is given by…[ NEET 2017]
ch-16_que_no-334_img_no1.png
  • a)
    ch-16_qn-334choice_img_no1.png
  • b)
    ch-16_qn-334choice_img_no2.png
  • c)
    ch-16_qn-334choice_img_no3.png
  • d)
    ch-16_qn-334choice_img_no4.png
Q.4
A particle of mass M and positive charge Q, moving with a constant velocity u1 =4(i ) m/s2, enters a region of uniform static magnetic field normal to the x-y plane.The region of the magnetic field extends from x = 0 to x = L for all values of y. Afterpassing through this region, the particle emerges on the other side after 10 millisecondswith a velocity The correct statement(s) is (are)
ch-16_que_no-335_img_no1.png
  • a) The direction of the magnetic field is −z direction.
  • b) The direction of the magnetic field is +z direction.
  • c) The magnitude of the magnetic field 50πM/3Q units.
  • d) The magnitude of the magnetic field is 100πM/3Q units.
Q.5
A steady current I flows along an infinitely long hollow cylindrical conductor of radius R.This cylinder is placed coaxially inside an infinite solenoid of radius 2R. The solenoid hasn turns per unit length and carries a steady current I. Consider a point P at a distance rfrom the common axis. The correct statement(s) is (are)…[ IIT advance 2013]
  • a) In the region 0 < r < R, the magnetic field is non-zero.
  • b) In the region R < r < 2R, the magnetic field is along the common axis.
  • c) In the region R < r < 2R, the magnetic field is tangential to the circle of radius r,centered on the axis.
  • d) In the region r > 2R, the magnetic field is non-zero.
Q.6
Paragraph The figure shows a circular loop of radius a withtwo long parallel wires (numbered 1 and 2) all inthe plane of the paper. The distance of each wirefrom the centre of the loop is d. The loop and thewires are carrying the same current I. The currentin the loop is in the counterclockwise direction ifseen from above. Q338A) When d ≈ a but wires are not touching the loop, it is found that the net magnetic field onthe axis of the loop is zero at a height h above the loop. In that case
ch-16_que_no-338_img_no1.png
  • a) current in wire 1 and wire 2 is the direction PQ and RS, respectively and h ≈ a
  • b) current in wire 1 and wire 2 is the direction PQ and SR, respectively and h ≈ a
  • c) current in wire 1 and wire 2 is the direction PQ and SR, respectively and h ≈ 1.2 a
  • d) current in wire 1 and wire 2 is the direction PQ and RS, respectively and h ≈ 1.2 a
Q.7
Consider d >> a, and the loop is rotated about its diameter parallel to the wires by 30° from the position shown in the figure. If the currents in the wires are in the oppositedirections, the torque on the loop at its new position will be (assume that the net field dueto the wires is constant over the loop)
ch-16_que_no-339_img_no1.png
  • a)
    ch-16_qn-339choice_img_no1.png
  • b)
    ch-16_qn-339choice_img_no2.png
  • c)
    ch-16_qn-339choice_img_no3.png
  • d)
    ch-16_qn-339choice_img_no4.png
Q.8
Four charges Q1, Q2, Q3 and Q4 of same magnitude are fixed along the x axis at x = −2a,−a, +a and +2a, respectively. A positive charge q is placed on the positive y axis at adistance b >Four options of the signs of these charges are given in List I. The directionof the forces on the charge q is given in List II. Match List I with List II and select thecorrect answer using the code given below the lists. Code :
List I List II
P. Q1, Q2, Q3, Q4 all positive +x
Q. Q1, Q2 positive; Q3, Q4 negative −x
R. Q1, Q4 positive; Q2, Q3 negative +y
S. Q1, Q3 positive; Q2, Q4 negative −y

ch-16_que_no-340_img_no1.png
  • a) P-3, Q-1, R-4, S-2
  • b) P-4, Q-2, R-3, S-1
  • c) P-3, Q-1, R-2, S-4
  • d) P-4, Q-2, R-1, S-3
Q.9
A conductor (show in the figure) carrying constant current I is kept in the x-y plane in auniform magnetic field B. If F is the magnitude of the total magnetic force acting on theconductor, then the correct statement(s)is(are) …[IIT Advance 2015]
ch-16_que_no-341_img_no1.png
  • d) If B is along z , F = 0
  • a) If B is along z
  • b) If B is along x , F =0
  • c) If B is along y , F ∝ (L + R)
Q.10
In a thin rectangular metallic strip a constant current I flows along the positive x-direction, as shown in the figure. The length, width and thickness of the strip are l,w and d, respectively. A uniform magnetic field B is applied on the strip along the positive y-direction. Due to this, the charge carriers experience a net deflection along the z-direction. This results in accumulation of charge carriers on the surface PQRS and appearance of equal and opposite charges on the face opposite to PQRS. A potential difference along the z-direction is thus developed. Charge accumulation continues until the magnetic force is balanced by the electric force. The current is assumed to be uniformly distributed on the cross section of the strip and carried by electrons. Q342A) Consider two different metallic strips (1 and 2) of the same material. Their lengths are the same, widths are w1 and w2 and thicknesses are d1 and d2, respectively. Two points K and M are symmetrically located on the opposite faces parallel to the x-y plane (see figure). V1 and V2 are the potential differences between K and M in strips 1 and 2, respectively. Then, for a given current I flowing through them in a given magnetic field strength B, the correct statement(s) is (are)
ch-16_que_no-342_img_no1.png
  • a) If w₁ = w₂ and d1 = 2d2, then V2 = 2V1
  • b) If w₁ = w₂ and d1 = 2d2, then V₂ = V₁
  • c) If w1 = 2w2 and d₁ = d₂, then V2 = 2V1
  • d) If w1 = 2w2 and d₁ = d₂, then V₂ = V₁
Q.11
A conducting loop in the shape of a right angled isosceles triangle of height 10 cm is kept such that the 90° vertex is very close to an infinitely long conducting wire (see the figure). The wire is electrically insulated from the loop. The hypotenuse of the triangle is parallel to the wire. The current in the triangular loop is in counterclockwise direction and increased at a constant rate of 10 A s-Which of the following statement(s) is(are) true?
ch-16_que_no-343_img_no1.png
  • a) The induced current in the wire is in opposite direction to the current along the hypotenuse
  • b) The magnitude of induced emf in the wire is volt (µ0/π) volts
  • c) There is a repulsive force between the wire and the loop
  • d) If the loop is rotated at a constant angular speed about the wire, an additional emf of (µ0/π) volt is induced in the wire
Q.12
Consider two identical galvanometers and two identical resistors with resistance R. If the internal resistance of the galvanometers RC < R/2, which of the following statement(s) about any one of the galvanometers is(are) true? ..[ IIT Advance 2016]
  • a) The maximum voltage range is obtained when all the components are connected in series
  • b) The maximum voltage range is obtained when the two resistors and one galvanometer are connected in series, and the second galvanometer is connected in parallel to the first galvanometer
  • c) The maximum current range is obtained when all the components are connected in parallel
  • d) The maximum current range is obtained when the two galvanometers are connected in series and the combination is connected in parallel with both the resistors
Q.13
A, Q.345B and Q.345C by appropriately matching the information given in the three columns of the following table. Q345 )A charged particle (electron or proton) is introduced at the origin (x = 0, y = 0, z = 0) with a given initial velocity v. A uniform electric field (E ) and a uniform magnetic field B exist everywhere. The velocity v , electric field E and magnetic field B are given in column 1, 2 and 3, respectively. The quantities E0, B0 are positive in magnitude Q345A . In which case will the particle move in a straight line with constant velocity ?
column 1 column 2 column 3
(I) Electron with (i) E =E0 z (P)B = -B0 x
(II) Electron with (ii)E = -E0 y (Q) B =B0x
(III) Proton with v = 0 (iii) E = -E0 x (R) B = B0y
(IV) Proton with (iv) E = E0 x (S) B =B0 z
  • a) (II) (iii) (S)
  • b) (IV) (i) (S)
  • c) (III) (ii) (R)
  • d) (III) (iii) (P)
Q.14
A symmetric star shaped conducting wire loop is carrying a steady state current I as shown in the figure. The distance between the diametrically opposite vertices of the star is 4a. The magnitude of the magnetic field at the center of the loop is … [ IIT Advance2017]
ch-16_que_no-346_img_no1.png
  • a)
    ch-16_qn-346choice_img_no1.png
  • b)
    ch-16_qn-346choice_img_no2.png
  • c)
    ch-16_qn-346choice_img_no3.png
  • d)
    ch-16_qn-346choice_img_no4.png
Q.15
) A uniform magnetic field B exists in the region between x = 0 and x = 3R/2 (region 2 in the figure) pointing normally into the plane of the paper. A particle with charge +Q and momentum p directed along x-axis enters region 2 from region 1 at point P1(y = –R). Which of the following options(s) is/are correct ? [ IIT Advance 2017]
ch-16_que_no-347_img_no1.png
  • a) For the particle will enter region 3 through the point P2 on x-axis
    ch-16_qn-347choice_img_no1.png
  • b) For the particle will re-enter region 1
    ch-16_qn-347choice_img_no2.png
  • c) For a fixed B, particle of same charge Q and same velocity v, the distance between the point P1 and the point of re-entry into region 1 is inversely proportional to mass of the particle
  • d) When the particle reinters region 1 through the longest possible path in region 2, the magnitude of the change in its linear momentum between point P1 and the farthest point from y-axis is p/√2
Q.16
A cyclotron is operating at frequency of 12×106Hz. Mass of deuteron is 3.3× 10⁻²⁷Kg and charge on deuteron is 1.6×10⁻¹⁹ coulombTo accelerate deuterons the magnetic induction of the necessary magnetic field is ..[ AFMC 2000]
  • a) 0.016 tesla
  • b) 0.16 tesla
  • c) 16 tesla
  • d) 1.6tesla
Q.17
A particle of charge -10×10⁻¹⁸ coulomb moving with velocity 10ms-1 along the x axis enters a region where a magnetic field induction B is along the y-axis, and an electric filed of magnitude 104 V/m is along the negative z-axis. If the charged particle continues moving along the x-axis, the magnitude of b is [ AIEEE 2003]
  • a) 103 Wb/m²
  • b) 105 Wb/m²
  • c) 1016 Wb/m²
  • d) 10-3 Wb/m²
Q.18
A long solenoid has 200 turns per cm and carries a current i. The magnetic field at its centre is 6.28×10⁻² Weber/mAnother long solenoid has 100turns per cm and it carries a current i/The value of the magnetic field at its centre is [ AIEE 2006]
  • a) 1.05×10⁻² Weber/ m2
  • b) 1.05×10⁻⁵ Weber/ m2
  • c) 1.05×10⁻³ Weber/ m2
  • d) 1.05×10⁻⁴ Weber/ m2
Q.19
An electron of mass 9×10⁻³¹ kg, charge 1.6 ×10⁻¹⁹ C moving with velocity 106 m/s enters a region of magnetic field of strength 5×10⁻⁵T perpendicular to the field. Find the radius of the circle described by it
  • a) 9.0 cm
  • b) 11.25 cm
  • c) 13.5 cm
  • d) 15.75 cm
Q.20
A proton of mass 1.67×10⁻²⁷ kg and charge 1.6×10⁻¹⁹ C is projected with a speed of 2×106 m/s at an angle of 60° to the x-axis. If a uniform magnetic field of 0.104 tesla is applied along the Y-axis, the path of the proton is [ IIT 1995]
  • a)a circle of radius=0.2 m and time period=π×10-7 s
  • b) a circle of radius=0.1 m and time period=2π×10-7 s
  • c)a helix of radius=0.1 m and time period=2π×10-7 s
  • d)a helix of radius=0.2 m and time period=4π×10-7 s
Q.21
A straight conductor of length 0.3 metre is placed in uniform magnetic field of induction 8 × 10⁻⁴ tesla, normal to the lines of the force. A current of 2.5 ampere flows through it. The mechanical force acting on the conductor, is
  • a) 6 Newton
  • b) 6 × 10⁻⁴ newton
  • c) 6 × 10⁻² newton
  • d) 6 × 10⁻³ newton
Q.22
Circular coil of radius 0.314 m carrying current of 2A produces a magnetic field of 2 ×10⁻⁴ T at its centre. The number of turns of the circular coil is
  • a) 25
  • b) 50
  • c)80
  • d)100
Q.23
The earth's magnetic induction at certain point is 7 × 10⁻⁵ Wb/mthis is to be annulled by the magnetic induction at the centre of a circular conducting loop of radius 10 cm. The required current in the loop is ....
  • a) 0.11A
  • b) 0.05A
  • c)11.15 A
  • d)0.5A
Q.24
An electron is moving in a circular path under theinfluence of a transverse magnetic field of 3.57 × 10⁻² T. If the value of e/m is 1.76 × 1011 C/kg, the frequency of revolution ofthe electron is…[NEET II-2016]
  • a) 62.8 MHz
  • b) 6.28 MHz
  • c) 1 GHz
  • d) 100 MHz
Q.25
A wire carrying a current of 5A lies perpendicular to a uniform magnetic field. The force per unit length is 1.25 ×10⁻⁷ N/cm. the magnetic field is
  • a) 2.5 mT
  • b) 2.5 µT
  • c) 2.5 mG
  • d) 2.5 µG
Q.26
If the incuced emf's in the primary and secondary coils of inductance is 2mV and 5.12 mV when the rate of change of current through either of these is 20 ampere per second. If the coefficient of coupling is one, the mutual inductance is ... [ AFMC 1998]
  • a) 3.56 ×10⁻⁴ henry
  • b) 1.56 × 10⁻⁴ henry
  • c) 1.6 × 10⁻⁴ henry
  • d) 2.56 × 10⁻⁴ henry
Q.27
The magnetic field Bo due to current carrying circular loop of radius 12cm at its center is 0.5 ×10⁻⁴T. The magnetic field due to this loop at a point on the axis at a distance of 5cm from the center is .. [ AFMC 2002]
  • a) 3.9×10⁻⁵ T
  • b) 9.3×10⁻⁵ T
  • c)6.3×10⁻¹⁵ T
  • d) 3.6×10⁻⁵ T
Q.28
When a proton is accelerated through 1V then its kinetic energy will be... [ CBSE-PMT 1999]
  • a) 1840 eV
  • b) 13.6eV
  • c) 1 eV
  • d) 0.54eV
Q.29
A galvanometer has a coil of resistance 100Ω and gives a full-scale deflection for 30 mA current. It is to work as a voltmeter of 30 Volt range, the resistance required to be added will be .... [ CBSE-PMT 2010]
  • a) 900 Ω
  • b) 1800 Ω
  • c)500 Ω
  • d)1800 Ω
Q.30
The magnetic force acting on a charged particle of charge -2µC in a magnetic field of 2T acting in y direction, when the particle velocity is (2i+3j)×106 ms-1, is... [ CBSE-PMT 2009]
  • a)4N in z-direction
  • b) 8N in y-direction
  • c)8N in z-direction
  • d)8N in -z-direction
0 h : 0 m : 1 s