Q.1
Two parallel wires each of 0.5 m in length atre at distance 1 metre from each other. If current through each wire is 1 amp, then force between the two wires is
  • a) 10-7 N
  • b) 0.5 N
  • c)107 N
  • d)5 ×1014 N
Q.2
An electron of mass m is accelerated through a potential difference of V and then it enters a magnetic field of induction B normal to the lines. the radius of circular path is
  • a)
    ch-16_qn-200choice_img_no1.png
  • b)
    ch-16_qn-200choice_img_no2.png
  • c)
    ch-16_qn-200choice_img_no3.png
  • d)
    ch-16_qn-200choice_img_no4.png
Q.3
An electron moves in a circular arc of radius 10 m at a constant speed of 2×107 m/s with its plane of motion normal to the magnetic flux density of 10-5T. What value does, from this set of figure, give for the specific charge of the electron?
  • a)2 × 102 C/kg
  • b) 2 ×105 C/kg
  • c)5 ×106 C/kg
  • d)2 ×1011 C/kg
Q.4
A battery is connected between to points A and B on the circumference of a uniform conducting ring of radius r and resistance R. One of the arc AB of the ring subtends angle θ at the centre. The value of the magnetic induction at the centre due to the current in the ring is
  • a) Proportional to 2( 180° - θ)
  • b) inversely proportional to r
  • c)zero , only if θ=180°
  • d)zero for all values of θ
Q.5
If a proton is projected in a direction perpendicular to a uniform magnetic field with velocity v and an electron is projected along the line of force, what will happen to proton and electron?
  • a) the electron will travel along a circle with constant speed and the proton will move along a straight line
  • b) proton will move in a circle with constant speed and there will be no effect on the motion of electron
  • c)there will not be any effect on the motion of electron and proton
  • d)the electron and proton both will follow the path of a parabola
Q.6
An electron accelerated through a potential difference of V passes through a magnetic field experiences a force F. If the accelerating potential is increased to 2V, the electron in the same magnetic field will experience force
  • a) F
  • b) F/2
  • c) √2 F
  • d) 2F
Q.7
At a distance of 10cm from long straight wire, carrying current, the magnetic field is 0.04 tesla. At the distance of 40 cm, the magnetic field will be
  • a)0.01 T
  • b) 0.02T
  • c)0.08 T
  • d)0.16 T
Q.8
A circular coil of radius 4 cm having 20 turns carries a current of 3A. It is placed in a magnetic field of intensity 0.5 weber/mThe magnetic dipole moment of coil is
  • a) 0.15 amp × m2
  • b) 0.30 amp × m2
  • c)0.45 amp m2
  • d)0.60 amp × m2
Q.9
If a particle of charge 10-12 C moving along the x-direction with velocity 105 m/s experiences a force of 10-10 N in y-direction due to magnetic field, then the minimum magnetic field is
  • a) 6.26 × 103 tesla in -direction
  • b) 10-15 tesla in z- direction
  • c)103 tesla in z-direction
  • d)10-3 tesla in z-direction
Q.10
A wire of 2m is bent in the form of a circular loop. The magnetic moment of the loop when 1A current flows through it is ......Am2.
  • a) 2π
  • b) π/2
  • c) π/4
  • d) 1/π
Q.11
When current is passed through a circular wire prepared from long conducting wire, magnetic field produced at its centre is B. Now loop having two turns in prepared from the same wire and the same current is passed through it. The magnetic field at its centre will be
  • a)B/4
  • b) B/2
  • c)4B
  • d)2B
Q.12
Electric current "I" flows through a hexagonal loop of side 'a'. Magnetic field ar its centre is
  • a)
    ch-16_qn-210choice_img_no1.png
  • b)
    ch-16_qn-210choice_img_no2.png
  • c)
    ch-16_qn-210choice_img_no3.png
  • d)
    ch-16_qn-210choice_img_no4.png
Q.13
Two particles of mass m and charge q are attached with two ends, one with each end, of rod length 2r. The rod is rotated with angular speed ω about its mid point. The ratio of magnetic moment produced and total angular momentum of these particles to ....
  • a) q/2m
  • b) q/m
  • c)2q/m
  • d)q/πm
Q.14
Two very long conducting parallel wires are separated by a distance d from each other and the same current I is passing through them in mutually opposite directions. A particle of charge q passes through a point which is at distance d/2 from both wires, with velocity v, perpendicularly to the plane formed by the wires. Resulting magnetic force acting on this particle is ...
  • a)
    ch-16_qn-212choice_img_no1.png
  • b)
    ch-16_qn-212choice_img_no2.png
  • c)
    ch-16_qn-212choice_img_no3.png
  • d) zero
Q.15
A stationary charged particle does not experience any net electromagnetic force, then ...
  • a)magnetic field may be zero or non-zero
  • b) magnetic field must be zero
  • c)electric field may be zero or non zero
  • d)electric field must be zero
Q.16
Electric current I flows through the wall of conducting pipe of infinite length, in a direction parallel to its length, then...
  • a) magnetic field is non-zero and equal at all points in inner region of the pipe
  • b) magnetic field is zero at all points in the inner region of pipe
  • c)electric field is zero only on the axis of the pipe
  • d)magnetic field is different at different points in the inner region of the pipe
Q.17
No magnetic force acts if ... is stationary
  • a) an electric dipole
  • b) magnetic dipole
  • c)a coil carrying current
  • d)a straight conductor carrying current
Q.18
A very long solenoid of length L has n layers. There are N turns in each layer. Diameter of the solenoid is D and current I passes through it, then magnetic field;d at the centre of solenoid is
  • a) directly proportional to D
  • b) inversely proportional to D
  • c) independent of D
  • d) directly proportional to L
Q.19
There are 200 turns per centimeter of avery long solenoid. If 2.5 A current passes through it, then the magnetic field at its centre on the axis is ... T
  • a)3.14 × 10-2
  • b) 6.28 × 10-2
  • c)9.42 × 10-2
  • d)12.56 × 10-2
Q.20
If a proton is moving with velocity 3 ×105 m/s at an angle of 30° in a magnetic field 0.3 T, then the radius of curvature of its trajectory will be .. [ for proton e/m=108 C/kg]
  • a) 0.5 cm
  • b) 0.02 cm
  • c)1.25 cm
  • d)2.0 cm
Q.21
A moving charge gains energy due to ....
  • a) electric field
  • b) magnetic field
  • c)both these fields
  • d)none of these fields
Q.22
In a region E and B represent electric and magnetic field respectively. If an electron moves with constant velocity (v) through that region, then the region may not have ....
  • a)E=0, B=0
  • b) E=0 , B ≠ 0
  • c)E ≠ 0, B=0
  • d)E ≠ 0 , B ≠ 0
Q.23
Two beams of protons moving parallel and in the same direction, will
  • a) Attract each other
  • b) exerts no force on each other
  • c)repel each other
  • d)can't say anything
Q.24
Unit of permeability is ........
  • a) (T - A)/m
  • b) (T-m)/A
  • c)(m-A)/T
  • d)none of them
Q.25
Two wires carrying current are parallel to each other, the force existing between them is F, IF the current flowing through them is doubled and distance between them is made four times, then force acting between them will be
  • a) 2F
  • b) F
  • c) F/2
  • d) F/4
Q.26
Assume the mass of proton to be nearly 2000 times the mass of an electron. A proton and an electron having equal momentum enter into a magnetic field at right angle to the direction of field. The ratio of the radii of their tracks will be .....
  • a)2000 : 1
  • b) 1 : 20000
  • c)1 : 1
  • d)none of these
Q.27
Certain length of wire carries a steady current. It is bent to form a circular loop. The magnetic field induced at the centre of the loop is B. If the same length is now bent to give a double loop of smaller radius then the magnetic field at the centre caused by the same current is ....
  • a) B/2
  • b) B
  • c)2B
  • d)4B
Q.28
An electron moves with velocity v in x-direction. If the magnetic field acts in y-direction then the force on the electron acts in .....
  • a) x-direction
  • b) y-direction
  • c)z-direction
  • d)-z-direction
Q.29
The magnetic field produced inside a current carrying long solenoid does not depend on....
  • a) number of turns per unit length
  • b) current flowing through it
  • c) radius of solenoid
  • d) all of them
Q.30
In a hydrogen atom, if an electron makes 6.6×1015 rev/s around the nucleus in an orbit of radius 2.1 Å then the magnetic moment will be ....Am2
  • a)1.46 × 10-15
  • b) 1.46 × 10-10
  • c)1.46 × 10-22
  • d)1.46 × 10-26
0 h : 0 m : 1 s