Q.1
When a straight conductor is carrying an electric current
  • a)there are circular magnetic line of force around it
  • b) there are no magnetic line of force near it
  • c)there are magnetic lines of force parallel to conductor along the direction of current
  • d)there are magnetic lines of force parallel to conductor opposite to the direction of current
Q.2
The change in the kinetic energy of a charged particle moving in a uniform magnetic field will be zero when its velocity is
  • a) parallel to the magnetic field
  • b) perpendicular to the magnetic field
  • c)at any angle with the magnetic field
  • d)in all of the above cases
Q.3
A current of 5 ampere is passed through a straight wire of length 6cms then the magnetic induction at a point 5cms from either end of the wire is
  • a) 0.25 gauss
  • b) 0.12 gauss
  • c)0.15 gauss
  • d)0.30 gauss
Q.4
A conducting rod PQ of length l carrying a current I is suspended from a support as shown in figure. A uniform magnetic field B perpendicular to PQ and directed away from the reader is applied. If the mass of the bar is M, the tension in each string is
ch-16_que_no-176_img_no1.png
  • a) Mg/2
  • b) (Mg+IB/)/2
  • c) (Mg -IBl)/2
  • d) Mg - (IBl)/2
Q.5
A beam of electrons is accelerated through a potential difference V. It is then passed normally through a uniform magnetic field where it moves in a circle of radius r. It would have moved in a circle of radius 2r if it were initially accelerated through a potential difference .....
  • a) √2 V
  • b) 2 V
  • c)2√2 V
  • d)4 V
Q.6
The strength of the magnetic field due to a long straight conductor is
  • a) same everywhere around the conductor
  • b) inversely proportional to the distance from the conductor
  • c) inversely proportional to the square of the distance from the conductor
  • d) inversely proportional of cube of the distance from the conductor
Q.7
A square frame of side L carries a current i and the field at the centre of the frame is B. The square frame is recast into circular coil of radius R. When same current i is passed through the circular coil, the magnetic field at its centre is B'. The ratio B/B' is
  • a)8/π2
  • b) 8√2 / π2
  • c)16/π2
  • d)(8/√2)π2
Q.8
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.9
The magnetic induction at point P which is distance 4cm from along current carrying wire is 10-3 tesla. The field of induction at a distance 12cm from the same current would be
  • a) 3.33 ×10-4 tesla
  • b) 1.11 × 10-4 tesla
  • c)3 × 10-3 tesla
  • d)9 × 10-3 tesla
Q.10
The magnetic field at the centre of a square loop of side L carrying current I is
  • a)
    ch-16_qn-180choice_img_no1.png
  • b)
    ch-16_qn-180choice_img_no2.png
  • c)
    ch-16_qn-180choice_img_no3.png
  • d) None of the above
Q.11
A circular coil of 50 turns carries a current of 0.2A. The earth's magnetic field is 6×10-5 T. the net field at the centre of coil is zero. The radius of the coil is
  • a)1.047 cm
  • b) 10.47 cm
  • c)1.047 m
  • d)10.47 m
Q.12
A circular coil of radius 4 cm having 5 turns carries a current of 2A. It is placed in uniform magnetic field of intensity 0.1 weber/mThe work done to rotate the coil from the equilibrium position through 180° is
  • a) 0.1 J
  • b) 0.2 J
  • c)0.4 J
  • d)0.8 J
Q.13
A long hollow metallic cylinder of radius R has a current i ampere. The magnetic induction B away from the axis at a distance r from the axis varies as shown in option
  • a)
    ch-16_qn-183choice_img_no1.png
  • b)
    ch-16_qn-183choice_img_no2.png
  • c)
    ch-16_qn-183choice_img_no3.png
  • d)
    ch-16_qn-183choice_img_no4.png
Q.14
The plane of a rectangular loop of wire with sides 0.05 m and 0.08 m is parallel to a uniform magnetic field of induction 1.5×10-2 tesla. A current of 10.0 amp. flows through the loop. If the side of length 0.08 m in normal and the side of length 0.05 m is parallel to the line of induction, then torque acting on it is
  • a) 6000 Newton × metre
  • b) Zero
  • c) 1.2 × 10-2 newton × metre
  • d) 6 × 10-4 newton × metre
Q.15
A rectangular coil of cross-section A is placed in uniform magnetic field B as shown in figure. The magnetic flux through the coil is
ch-16_que_no-185_img_no1.png
  • a)B.A
  • b) B.Asinα
  • c)B.Acosα
  • d)none of these
Q.16
Two wires A and B carry current as shown in figure the magnetic interactions
ch-16_que_no-186_img_no1.png
  • a) Push I2 away from I1
  • b) Pull I2 closer to I1
  • c)Turn I2 clockwise
  • d)Turn I2 counter clockwise
Q.17
A solenoid has 1000 turns wound on a length of 20cm. It carries a current of 5A. The magnetic field at one end of the solenoid is
  • a)0.031 T
  • b) 0.0155 T
  • c)0.00775 T
  • d)0.062 T
Q.18
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.19
A wire bent in the form of a regular polygon of n sides, is inscribed in a circle of radius 'a' metre . If i ampere is the current flowing through wire, then the magnetic flux density at the centre of the circle is
  • a)
    ch-16_qn-189choice_img_no1.png
  • b)
    ch-16_qn-189choice_img_no2.png
  • c)
    ch-16_qn-189choice_img_no3.png
  • d)
    ch-16_qn-189choice_img_no4.png
Q.20
Two identical coils carry equal currents have a common centre and their planes are at right angles to each other. What is the ratio of magnitudes of the resultant magnetic field and the field due to one coil alone at the centre
  • a) 2 : 1
  • b) 1 : 1
  • c) 1 : √2
  • d)√2 : 1
Q.21
A wire bent in the form of sector of radius r subtending an angle θo at centre, as shown in figure is carrying a current i. the magnetic field at O is
ch-16_que_no-191_img_no1.png
  • a)
    ch-16_qn-191choice_img_no1.png
  • b)
    ch-16_qn-191choice_img_no2.png
  • c)
    ch-16_qn-191choice_img_no3.png
  • d)zero
Q.22
A uniform wire of mass 10-3 kg/cm is held at rest in horizontal position without any support by placing it in a uniform, perpendicular magnetic field. The wire is carrying a current of 10A. The magnetic field is
  • a) 0.1 T
  • b) 1.0 T
  • c) 10-2 T
  • d) 10-3 T
Q.23
Two thick wire and two thin wires all of the same material and same length form a square in three different ways P, Q, and R as shown in figure. With the current connections as shown, the magnetic field at the centre of the square is zero in case of :
ch-16_que_no-193_img_no1.png
  • a) P only
  • b) P and Q only
  • c)Q and R only
  • d)P and R only
Q.24
Current I flows through a long conducting wire bent at right angles as shown in figure. The magnetic field at a point P on the right bisector or ∠ XOY at distance r from O is
ch-16_que_no-194_img_no1.png
  • a)
    ch-16_qn-194choice_img_no1.png
  • b)
    ch-16_qn-194choice_img_no2.png
  • c)
    ch-16_qn-194choice_img_no3.png
  • d)
    ch-16_qn-194choice_img_no4.png
Q.25
A circular coil of radius 20cm having 50 turns carries a current of 2A. The magnetic moment of the coil is
  • a) 0.4 π A-m2
  • b) 4π A-m2
  • c)40 π A-m2
  • d)400 π A-m2
Q.26
Magnetic field due to a current carrying torodal solenoid is independent of
  • a)its number of turns
  • b) current
  • c)radius
  • d)none of the above
Q.27
What is the magnetic field in the empty space enclosed by the toroidal solenoid of radius R?
  • a) infinity
  • b) µoI /(4πR)
  • c)µoπI /(4πR)
  • d)zero
Q.28
A wire bent in the form of right angled triangle ABC as shown in figure carries a current 1 A. It is placed in the region of uniform magnetic field B=0.2T as shown in figure. IF AC=1m, the net force on the wire is
ch-16_que_no-196_img_no1.png
  • a) 1.73 N
  • b) 3.46 N
  • c) 2.732 N
  • d) Zero
Q.29
If a long copper rod carries a direct current the magnetic field associated with current will be
  • a)inside the rod only
  • b) outside the rod only
  • c)both inside and outside the rod
  • d)neither inside nor outside the rod
Q.30
As shown in figure rectangular coil of cross-section area A placed in uniform magnetic field B directed along Z-axis. The torque on the coil is
ch-16_que_no-198_img_no1.png
  • a) ABI along +Ve Y-axis
  • b) ABI along -ve Y-axis
  • c)ABI along +VE X-axis
  • d)zero
0 h : 0 m : 1 s