Q.1.
A current I=1 A flowing through an infinitely long wire P1 divides between two long wires P2 and P3 at junction C as shown in figure. The magnitude of magnetic field at point O due to wire is .......
-
0%
a) 10-7 T
-
0%
b) 5 × 10-7 T
-
67%
c) 10-6 T
-
33%
d) 0
Q.2.
As shown in figure, current I flows through a long conducting wire bent at right angles. The magnetic field at point P on the right bisector of the angle at a distance 'r' from O is .....
-
0%
a)
-
100%
b)
-
0%
c)
-
0%
d)
Explanation
Q.3.
If current is doubled, the deflection is also doubled in .....
-
50%
a) a tangent galvanometer
-
0%
b) a moving coil galvanometer
-
0%
c)both (a) and (b)
-
50%
d)none of these
Q.4.
Two wires of same length are shaped into a square and a circle. If they carry same current, ratio of the magnetic moments is ......
-
50%
a) 2 : π
-
0%
b) π : 2
-
50%
c)π : 4
-
0%
d)4 : π
Q.5.
An electron is projected along the axis of a circular conductor carrying some current. Electron will experience force .......
-
0%
a) along the axis
-
0%
b) perpendicular to axis
-
50%
c) at an angle of 4° with axis
-
50%
d) no force experienced
Q.6.
A long starlight wire carrying a current of 30A is placed in an external uniform magnetic field of induction 4 × 10-4 T. The magnetic field is acting parallel to the direction of current. The magnitude of the resultant magnetic induction in tesla at a point 2cm away from wire is .....
-
50%
a)10-4
-
50%
b) 3 × 10-4
-
0%
c)5 × 10-4
-
0%
d)6 × 10-4
Explanation
Q.7.
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 the centre of the coil such that r >> R, varies as .....
-
0%
a) 1/r
-
0%
b) 1 / r 3/2
-
100%
c)1 / r 2
-
0%
d)1 / r 3
Q.8.
A current flows in a conductor from east to west. the direction of the magnetic field at a point above the conductor is .....
-
0%
a) towards east
-
0%
b) towards west
-
50%
c)towards north
-
50%
d)towards south
Q.9.
A horizontal long straight wire carries 10 A DC current. An electron travels perpendicular to the horizontal plane of this wire at a distance of 0.1m with velocity 5×106 m/s. Force acting on electron due to the current in wire is ....N
-
0%
a) zero
-
0%
b) 0.6 ×10-17
-
100%
c) 1.6 ×10-17
-
0%
d) 2.2 × 10-17
Q.10.
A 1 metre long wire at right angle to the magnetic field. A force of 1kg weight is acting on it in a magnetic field of 0.98 Tesla. The current flowing in it will be ....
-
0%
a)100 A
-
50%
b) 10A
-
50%
c)1A
-
0%
d)zero
Q.11.
Weber × ampere per metre is equal to .....
-
50%
a) joule
-
0%
b) newton
-
0%
c)henry
-
50%
d)watt
Q.12.
A current carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend upon
-
0%
a) shape of loop
-
0%
b) area of loop
-
0%
c)value of the current
-
100%
d)magnetic field
Q.13.
An electron and a proton enters a magnetic field perpendicularly. Both have same kinetic energy. Which of the following is true?
-
0%
a) Trajectory of electron is less curved
-
0%
b) trajectory of proton is less covered
-
50%
c) both trajectory are equally curved
-
50%
d) both move on straight line path
Q.14.
An electron is traveling in horizontally towards east. A magnetic field in a vertically downward direction exerts a force on the electron.....
-
0%
a)eastwards
-
0%
b) westwards
-
50%
c)northwards
-
50%
d)southwards
Q.15.
If current is passed in a spring, it .....
-
0%
a) gets compressed
-
0%
b) gets expanded
-
0%
c)oscillates
-
100%
d)remains unchanged
Q.16.
A charge q coulomb moves in a circle at n revolutions per second and radius of the circle is r metre, then magnetic field at the centre of the circle is ....
-
0%
a)
-
50%
b)
-
50%
c)
-
0%
d)
Q.17.
If velocity of an electron is (2i + 3j) m/s enters in the magnetic field of 4kT then .......
-
0%
a) it will move in the opposite direction of the magnetic field
-
50%
b) it will move in the direction of the magnetic field
-
0%
c) its speed will change
-
50%
d) direction of velocity will change
Q.18.
A current loop ABCD is held fixed on the plane of paper as shown in figure. the arcs BC ( radius=b) and DA ( radius=a) of the loop are by two wires AB and CD. A steady current I is flowing in the loop. Angle made by AB and CD at the origin O is 30°. Another straight thin wire with steady current I1 flowing out of the plane of the paper is kept at origin. The magnitude of magnetic field (B) due to the loop ABCD at the origin O is .... [ AIEEE 2008]
-
50%
a)
-
50%
b) zero
-
0%
c)
-
0%
d)
Explanation
Q.19.
Due to the presence of current I1 in question 289 ....
-
0%
a) force on loop is
-
0%
b) The force on AB and DC are zero
-
100%
c)the force on AD and BC are zero
-
0%
d) force on loop
Q.20.
Two circular single turn coils are so arranged in two mutually perpendicular planes such that their centers coincide. The radius of each coil is 2cm and same current of 5A flows through them. The magnetic induction at the common centre is approximately
-
0%
a) 12 × 10-5 T
-
50%
b) 22 × 10-5 T
-
50%
c)32 ×10-5 T
-
0%
d)42 ×10-5 T
Explanation
Q.21.
A rectangular loop carrying a current i is situated near a long straight wire such that the wire is parallel to one of the sides of the loop and is in the plane of the loop. If a steady current I is established in the wire as shown in figure, the loop will
-
50%
a) rotate about an axis parallel to the wire
-
50%
b) move away from the wire
-
0%
c) move towards the wire
-
0%
d) have non zero force in the y direction
Q.22.
A wire of length l carries a current i along the x-axis. A magnetic field exists which is given aa B=Bo(i + j + k) T. The magnitude of the magnetic force acting on the wire is
-
0%
a)ilBo
-
0%
b) 3ilBo
-
50%
c)√2 ilBo
-
50%
d)√3 ilBo
Q.23.
In a cozaxial, straight cable , the central conductor and the outer conductor carry currents in opposite directions. The magnetic field is zero
-
0%
a) Outside the cable, if currents are equal
-
0%
b) inside the inner conductor, if currents are unequal
-
100%
c)inside the outer conductor
-
0%
d)inbetween the two conductors, if currents are equal or unequal
Q.24.
Two wires are placed at (2, 0, 0) and (-2, 0, 0) and are carrying equal currents along negative z-axis. Magnetic field at point (0, 2 ,0) is along
-
0%
a)positive x -axis
-
50%
b) negative x-axis
-
0%
c)positive y-axis
-
50%
d)negative z-axis
Explanation
Q.25.
The vector form of Bio-savart law is
-
0%
a)
-
50%
b)
-
50%
c)
-
0%
d)
Q.26.
To obtain maximum intensity of magnetic field at appoint the angle between position vector of point and small elements of length of the conductor is
-
0%
a)0
-
0%
b) π/4
-
50%
c)π/2
-
50%
d)π
Q.27.
The value of magnetic field due to a small element of current carrying conductor at a distance r and lying on the plane perpendicular to the element of conductor is
-
0%
a) zero
-
50%
b) maximum
-
0%
c)inversely proportional to the current
-
50%
d)none of above
Q.28.
The value of intensity of magnetic field at a point due to a current carrying conductor is obtained from
-
0%
a) Gauss's law
-
0%
b) Faraday's law
-
0%
c)coulombs law
-
100%
d)Biot savart's law
Q.29.
The value of intensity of magnetic field at a point die to a current carrying conductor depends ..
-
0%
a) only on the value of current
-
50%
b) only on a small part of length of conductor
-
50%
c) on angle between the line joining the given point to the mid point of a small length and the distance between the small length of the point.
-
0%
d) On all above points
Q.30.
The resultant magnetic field at the point O due to the current carrying wire shown in figure is ...
-
100%
a) Points to wards right
-
0%
b) point towards left
-
0%
c)is zero
-
0%
d)is the same s due to the segment WX alone