86 + Interview Questions in MAGNETIC-EFFECT-OF-CURRENT-AND-MAGNETISM IN GENERAL AWARENESS Page 2 InterviewSolution

51.	A uniform magnetic field `vec(B) = 3 hat i + 4 hat j + hat k` exists in region of space. A semicircular wire of radius of 1 m carrying current 1 A having its centre at (2, 2, 0) is placed in x-y plane as shown in Fig. The force on semicircular wire will be A. `sqrt2(hati+hatj+hatK)`B. `sqrt2(hati-hatj+hatK)`C. `sqrt2(hati+hatj+hatK)`D. `sqrt2(-hati+hatj+hatK)`
Answer» Correct Answer - b

Discussion

52.	The ratio of the magnetic field at the centre of a current carrying circular coil to its magnetic moment is x. If the current and radius both are doubled the new ratio will becomeA. `2x`B. `4x`C. `x//4`D. `x//8`
Answer» Correct Answer - D

Discussion

53.	The dimensions of `(B^(2)R^(2)C^(2))/(2mu_(0))` (Where B is magnetic filed, and `mu_(0)` is permeability of free space , R resistance and C is capacitance) isA. `[ML^(-1)]`B. `[MLT^(-1)]`C. `[ML^(2)T^(-1)]`D. `[MLT^(2)]`
Answer» Correct Answer - A

Discussion

54.	Ratio of magnetic field at the centre of a current carrying coil of radius R and at a distance of `3R` on its axis isA. `10sqrt(10)`B. `20sqrt(10)`C. `2sqrt(10)`D. `sqrt(10)`
Answer» Correct Answer - A

Discussion

55.	The small angle between magnetic axis and geographical axis at a place is calledA. magnetic inclinationB. magnetic dipC. magnetic declinationD. none of the above
Answer» Correct Answer - C

Discussion

56.	The SI units of magentic permeability areA. `Wb A^-1m`B. `WbA^-1m^-1`C. `Hm`D. `Tm^-1A`
Answer» Correct Answer - B

Discussion

57.	In a certain region of space, there exists a uniform and constant electric field of strength E along x-axis and uniform constant magnetic field of induction B along z-axis. A charge particle having charge q and mass m is projected with speed v parallel to x-axis from a point (a, b, 0). When the particle reaches a point 2a, `b//2`, 0 its speed becomes 2v. Find the value of electric field strength in term of m, v and co-ordinates.A. `(3)/(2)(mv^(2))/(qa)`B. `(mv^(2))/(qb)`C. `(2mv^(2))/(qa)`D. `(mv^(2))/(2qa)`
Answer» Correct Answer - a

Discussion

58.	A circular coil carrying current behaves as aA. bar magnetB. horse shoe magnetC. magnetic shellD. solenoid
Answer» Correct Answer - C

Discussion

59.	In the potential energy of magnetic dipole is zero when `theta=`A. `0^@`B. `90^@`C. `180^@`D. `360^@`
Answer» Correct Answer - B

Discussion

60.	A proton enters in a uniform electric and magnetic fields E and B respectively. Velocity of proton is v. All the three vectors are mutually perpendicular. The proton is deflected along positive x-axis when either of the fields or both are switched on simultaneously. Which of the following statement(s) is/are correct ?A. V may be along positive y-axisB. E is along positive x-axisC. B may be along positive z-axisD. B may be along negative y-axis
Answer» Correct Answer - a,b,c

Discussion

61.	SI unit of magnetic pole strength isA. Ampere `metre^-1`B. Ampere `metre^-2`C. Ampere meterD. Ampere `metre^-2`
Answer» Correct Answer - C

Discussion

62.	Magnetic field strength due to a bar magnet at a point distant d from the center of magnetA. `1//d`B. `d`C. `d^3`D. `1//d^3`
Answer» Correct Answer - D

Discussion

63.	A long solenoid has n turns per metre and current IA is flowing through it. The magnetic field induciton at the ends of the solenoid isA. zeroB. `mu_0nI//2`C. `mu_0nI`D. `2mu_0NI`
Answer» Correct Answer - B

Discussion

64.	A charge q moves with a velocity `2m//s` along x- axis in a unifrom magnetic field `B=(hati+2hatj+3hatk)` tesla.A. Charge will experience a force in z-y planeB. Charge will experience a force along- y aixsC. Charge will experience a force + z aixsD. Charge will experience a force along - z axis
Answer» Correct Answer - A

Discussion

65.	Every iron atom in a ferromagnetic domain has a magnetic dipole moment equal to `9.27 xx 10^(-24) A m^(2)`. A ferromagetic domain in iron has the shape of a cube of side ` 1mum`. The maximum dipole moment occurs when all the dipoles are alligned. The molar mass of uiron is 55 g and its specific gravity is 7.9 .The magnetisation of the domain is .A. `8.0 xx 10^(5) A//m`B. `8.0 xx 10^(8) A//m`C. `8.0 xx 10^(11) A//m`D. `8.0 xx 10^(14) A//m`
Answer» Correct Answer - A

Discussion

66.	Magnetic moment of a current loop becomes k times when diameter of loop is made twice and number of turns is made three fold where, `k=`A. `2`B. `3`C. `6`D. `12`
Answer» Correct Answer - D

Discussion

67.	A positive charge particle enters and comes out (at `60^(@)` and `37^(@)` as shown) from a uniform magnetic field which is perpendicular to paper inwards in a finite space of width 60 cm as shown in the figure. Find the radius of curvature of the charged particle (in meter) when it is inside the magnetic field.
Answer» Correct Answer - 2

Discussion

68.	Magnetic moment of an electron in nth orbit of hydrogen atom isA. `(neh)/(pim)`B. `(neh)/(4pim)`C. `meh)/(2pin)`D. `(meh)/(4 pin)`
Answer» Correct Answer - B

Discussion

69.	Side of the regular hexagon is 2 meter. Magnetic field at point O due to the network shown in the figure `sqrt3B_(0)xx10^(-7)` T. Find value of `B_(0)`
Answer» Correct Answer - 2

Discussion

70.	A charge particle having charge q expericenec a `F_(1)q=(-hatj+hatk)N ` in a magnetic field B when is has velocity `v_(1)=(1.0)hati(m)/(s)`. The force becomes `F=q(hati-hatl)` when the velocity is charged to `F=q(hati-hatl)` magnetic induction vector at that point isA. `(hati+hatj+ hatk)T`B. `(hati-hatj- hatk)T`C. `(-hati-hatj+ hatk)T`D. `(hati+hatj- hatk)T`
Answer» Correct Answer - A

Discussion

71.	A charged particle (q.m) released from origin with velocity `v=v_(0)hati` in a uniform magnetic field `B=(B_(0))/(2)hati+(sqrt3B_(0))/(2)hatJ`. When z-co-ordinate has its maximum valueA. `v_(x)=0`B. `v_(y)=v_(0)`C. Both (a) and (b) are correctD. Both (a) and (b) are wrong
Answer» Correct Answer - d

Discussion

72.	A charged particle (q.m) released from origin with velocity `v=v_(0)hati` in a uniform magnetic field `B=(B_(0))/(2)hati+(sqrt3B_(0))/(2)hatJ`. Maximum z-coordinate of the particle isA. `(sqrt3mv_(0))/(B_(0)q)`B. `(2sqrt3mv_(0))/(B_(0)q)`C. `(2mv_(0))/(B_(0)q)`D. `(mv_(0))/(B_(0)q)`
Answer» Correct Answer - a

Discussion

73.	A charge praticule of sepeific charge (charge/ mass ) `alpha` is realsed from origin at time t=0 with velocity `v= v_(0)(hati+hatj)` in unifrom magnetic fields `B= B_(0)hati`. Co-ordinaties of the particle at time `t = (pi)/(B_(0)alpha)` areA. `(V_(0)/(2B_(0)alpha),sqrt(2V_(0))/(alphaB_(0)),(-V_(0))/(B_(0)alpha))`B. `((-V_(0))/(B_(0)alpha),0,0)`C. `(0,(2V_(0))/(B_(0)alpha),(V_(0)pi)/(2B_(0)alpha))`D. `((V_(0)pi)/(2B_(0)alpha),0, (-2V_(0))/(B_(0)alpha))`
Answer» Correct Answer - D

Discussion

74.	A wire of length 1 m placed in x-z plane carries current of 1 amp. The coefficient of friction between wire and the surface is `0.2` and mass of the wire is 2. The magnetic field of strengh 2 T exists along position y direction . Then choose the correct statment .A. Acceleration of wire is `0.5 m//s^(2)`B. Wire will not move at allC. Accceleration of wire is `m//s^(2)`D. Acceleration of wire is `2m//s^(2)`
Answer» Correct Answer - B

Discussion

75.	A charged particle (q.m) released from origin with velocity `v=v_(0)hati` in a uniform magnetic field `B=(B_(0))/(2)hati+(sqrt3B_(0))/(2)hatJ`. Z-component of velocity is `(sqrt3v_(0))/(2)` after in t=……….A. `(2pim)/(B_(0)q)`B. `(pim)/(B_(0)q)`C. `(pim)/(2B_(0)q)`D. `(2pim)/(4B_(0)q)`
Answer» Correct Answer - c

Discussion

76.	A charged particle (q.m) released from origin with velocity `v=v_(0)hati` in a uniform magnetic field `B=(B_(0))/(2)hati+(sqrt3B_(0))/(2)hatJ`. Pitch of the helical path described by the particle isA. `(2pimv_(0))/(B_(0)q)`B. `(sqrt3pimv_(0))/(2B_(0)q)`C. `(pimv_(0))/(B_(0)q)`D. `(2sqrt3pimv_(0))/(B_(0)q)`
Answer» Correct Answer - c

Discussion

77.	A charge particle having charge q expericenec a `F_(1)q=(-hatj+hatk)N ` in a magnetic field B when is has velocity `v_(1)=(1.0)hati(m)/(s)`. The force becomes `F=q(hati-hatl)` when the velocity is charged to `F=q(hati-hatl)` magnetic induction vector at that point isA. `(hati+hatj+ hatk)T`B. `(hati-hatj- hatk)T`C. `(-hati-hatj+ hatk)T`D. `(hati+hatj- hatk)T`
Answer» Correct Answer - A

Discussion

78.	Magnetic force on a charged particle is given by `vec F_(m) = q(vec(v) xx vec(B))` and electrostatic force `vec F_(e) = q vec (E)`. A particle having charge q = 1C and mass 1 kg is released from rest at origin. There are electric and magnetic field given by `vec(E) = (10 hat(i)) N//C for x = 1.8 m` and `vec(B) = -(5 hat(k)) T` for `1.8 m le x le 2.4 m` A screen is placed parallel to y-z plane at `x = 3 m`. Neglect gravity forces. Time after which the particle will collide the screen is (in seconds)A. `(1)/(5)(3+(pi)/(6)+(1)/(sqrt3))`B. `(1)/(5)(6+(pi)/(3)+sqrt3)`C. `(1)/(3)(5+(pi)/(6)+(1)/sqrt3)`D. `(1)/(3)(6+(pi)/(18)+sqrt3)`
Answer» Correct Answer - a

Discussion

79.	Magnetic force on a charged particle is given by `vec F_(m) = q(vec(v) xx vec(B))` and electrostatic force `vec F_(e) = q vec (E)`. A particle having charge q = 1C and mass 1 kg is released from rest at origin. There are electric and magnetic field given by `vec(E) = (10 hat(i)) N//C for x = 1.8 m` and `vec(B) = -(5 hat(k)) T` for `1.8 m le x le 2.4 m` A screen is placed parallel to y-z plane at `x = 3 m`. Neglect gravity forces. y-coordinate of particle where it collides with screen (in meters) isA. `(0.6(sqrt3-1))/(sqrt3)`B. `(0.6(sqrt3+1))/(sqrt3)`C. `1.2(sqrt3+1)D. `(1.2(sqrt3-1))/(sqrt3)`
Answer» Correct Answer - d

Discussion

80.	Three infinetely long wires 1 , 2 and 3 carry equal currents in the directions shown in fiugre. They are placed on the vertices of an equilateral triangle. Let F be the magnitude of force between any two wires. `F_(1)` is the magnitude of force on wire 1 and `F_(2)` the magnitude of force on wire 2. ThenA. `F_(1)=sqrt3F`B. `F_(2)=F`C. Both (a) and (b) are correctD. Both (a) and (b) are wrong
Answer» Correct Answer - c

Discussion

81.	A wire of length L, mass m and carrying a current I is suspended from point O as shown, An another infinitely long wire carrying the same current I is at a distance L below the lower end of the wire. Given i=2A, L=1m and m=0.1kg (In 2=0.693) What is the angular acceleration of the wire just after it is released from the position shown ?A. `6.2xx10^(-8)(rd)/(s^(2))`B. `2.1xx10^(-4)(rd)/(s^(2))`C. `4.5xx10^(-5)(rd)/(s^(2))`D. `9.3xx10^(-6)(rd)/(s^(2))`
Answer» Correct Answer - d

Discussion

82.	Equal currents I flow in two wires along x and y ax as shown. Match the following.
Answer» Correct Answer - (A) R,(B)Q,(C)R,(D)P

Discussion

83.	Two infinitely long straight current carrying wires are placed parallel to y-axis in xy plane. Each wire carries current I in opposite directions as shown. A charged particle of charge `+q` and mass m is project from position P(0,0,0a) with initial velocity v=i. Then A. The magnitude of initial acceleration of the particle `(mu_(0)lqv)/(2piam)`B. The direction of initial acceleration of the particle is parallel to positve x-axisC. The direction of initial acceleration of the particle is parallel to positive y-axisD. The radius of curvature of the path of the particle just after it is projected is `(2pimav)/(mu_(0)lq)`
Answer» Correct Answer - a,b,d

Discussion

84.	The force between two parallel current carrying wires is independent ofA. their distance of separationB. the length of the wiresC. the radii of the wiresD. the medium in which they are placed
Answer» Correct Answer - C

Discussion

85.	Some current carrying wires are given in Table-1 and graph of variation of magnetic field versus position of point P are given in Table-2. Match the graph given in Table-2 for the current carrying wire in Table-2.
Answer» Correct Answer - (A) R,(B)S,(C)P,(D)Q

Discussion

86.	Infinite number of straight wires each carrying current I are equally placed as shown in the figure Adjacent wires have current in opposite direction Net magnetic field at point `P` is .A. `(mu_(0)l In2)/(4pisqrt(3a))hatK`B. `(mu_(0)l In4)/(4pisqrt(3a))hatK`C. `(mu_(0)l In4)/(4pisqrt(3a))(-hatK)`D. zero
Answer» Correct Answer - D

Discussion

Explore topic-wise InterviewSolutions in .

The ratio of the magnetic field at the centre of a current carrying circular coil to its magnetic moment is x. If the current and radius both are doubled the new ratio will becomeA. `2x`B. `4x`C. `x//4`D. `x//8`

The dimensions of `(B^(2)R^(2)C^(2))/(2mu_(0))` (Where B is magnetic filed, and `mu_(0)` is permeability of free space , R resistance and C is capacitance) isA. `[ML^(-1)]`B. `[MLT^(-1)]`C. `[ML^(2)T^(-1)]`D. `[MLT^(2)]`

Ratio of magnetic field at the centre of a current carrying coil of radius R and at a distance of `3R` on its axis isA. `10sqrt(10)`B. `20sqrt(10)`C. `2sqrt(10)`D. `sqrt(10)`

The small angle between magnetic axis and geographical axis at a place is calledA. magnetic inclinationB. magnetic dipC. magnetic declinationD. none of the above

The SI units of magentic permeability areA. `Wb A^-1m`B. `WbA^-1m^-1`C. `Hm`D. `Tm^-1A`

A circular coil carrying current behaves as aA. bar magnetB. horse shoe magnetC. magnetic shellD. solenoid

In the potential energy of magnetic dipole is zero when `theta=`A. `0^@`B. `90^@`C. `180^@`D. `360^@`

SI unit of magnetic pole strength isA. Ampere `metre^-1`B. Ampere `metre^-2`C. Ampere meterD. Ampere `metre^-2`

Magnetic field strength due to a bar magnet at a point distant d from the center of magnetA. `1//d`B. `d`C. `d^3`D. `1//d^3`

A long solenoid has n turns per metre and current IA is flowing through it. The magnetic field induciton at the ends of the solenoid isA. zeroB. `mu_0nI//2`C. `mu_0nI`D. `2mu_0NI`

A charge q moves with a velocity `2m//s` along x- axis in a unifrom magnetic field `B=(hati+2hatj+3hatk)` tesla.A. Charge will experience a force in z-y planeB. Charge will experience a force along- y aixsC. Charge will experience a force + z aixsD. Charge will experience a force along - z axis

Magnetic moment of a current loop becomes k times when diameter of loop is made twice and number of turns is made three fold where, `k=`A. `2`B. `3`C. `6`D. `12`

Magnetic moment of an electron in nth orbit of hydrogen atom isA. `(neh)/(pim)`B. `(neh)/(4pim)`C. `meh)/(2pin)`D. `(meh)/(4 pin)`

Side of the regular hexagon is 2 meter. Magnetic field at point O due to the network shown in the figure `sqrt3B_(0)xx10^(-7)` T. Find value of `B_(0)`

A charged particle (q.m) released from origin with velocity `v=v_(0)hati` in a uniform magnetic field `B=(B_(0))/(2)hati+(sqrt3B_(0))/(2)hatJ`. When z-co-ordinate has its maximum valueA. `v_(x)=0`B. `v_(y)=v_(0)`C. Both (a) and (b) are correctD. Both (a) and (b) are wrong

A charged particle (q.m) released from origin with velocity `v=v_(0)hati` in a uniform magnetic field `B=(B_(0))/(2)hati+(sqrt3B_(0))/(2)hatJ`. Maximum z-coordinate of the particle isA. `(sqrt3mv_(0))/(B_(0)q)`B. `(2sqrt3mv_(0))/(B_(0)q)`C. `(2mv_(0))/(B_(0)q)`D. `(mv_(0))/(B_(0)q)`

A charged particle (q.m) released from origin with velocity `v=v_(0)hati` in a uniform magnetic field `B=(B_(0))/(2)hati+(sqrt3B_(0))/(2)hatJ`. Z-component of velocity is `(sqrt3v_(0))/(2)` after in t=……….A. `(2pim)/(B_(0)q)`B. `(pim)/(B_(0)q)`C. `(pim)/(2B_(0)q)`D. `(2pim)/(4B_(0)q)`

Equal currents I flow in two wires along x and y ax as shown. Match the following.

The force between two parallel current carrying wires is independent ofA. their distance of separationB. the length of the wiresC. the radii of the wiresD. the medium in which they are placed

Some current carrying wires are given in Table-1 and graph of variation of magnetic field versus position of point P are given in Table-2. Match the graph given in Table-2 for the current carrying wire in Table-2.