Choose the incorrect statements from the following regarding magnetic lines of field.
  • the direction of magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle points
  • magnetic field lines are closed curves
  • if magnetic field lines are parallel and equidistant, they represent zero field strength
  • relative strength of magnetic field is shown by the degree of closeness of the field lines.
A circular loop placed in a plane perpendicular to the plane of paper carries a current when the keys is ON. The current as seen from points A and B (in the plane of paper and on the axis of the coil) is anticlockwise and clockwise respectively. The magnetic field lines point from B to A. The N-pole of the resultant magnet is on the faces close to
  • A
  • B
  • A if the current is small, and B if the current is large
  • B if the current is small and A if the current is large.
For a current in a long straight solenoid, N- and S-poles are created at the two ends. Among the following statements, the incorrect statement is
  • the field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid
  • the strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil
  • the pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet
  • the N- and S-poles exchange position when the direction of current through the solenoid is reversed.
Choose the incorrect statement
  • Fleming’s right-hand rule is a simple rule to know the direction of induced current.
  • The right-hand thumb rule is used to find the direction of magnetic fields due to current carrying conductors.
  • The difference between the direct and alternating currents is that the current always flows in one direction, whereas the alternating current reverses its direction periodically.
  • In India, the AC changes direction after every \(\frac{1}{50}\) second.
The strength of magnetic field inside a long current carrying straight solenoid is
  • more at the ends than at the centre
  • minimum in the middle
  • same at all points
  • found to increase from one end to the other
The most important safety method used for protecting home appliances from short circuiting or overloading is by
  • earthing
  • use of fuse
  • use of stabilizers
  • use of electric meter.
Select the incorrect statement
  • Magnetic field lines are closed curves
  • No two field lines can cross each other
  • Field lines can cross each other
  • The relative strength of the magnetic field is shown by degree of closness of the field lines.
Magnetic field lines around a straight conductor forms a pattern of
  • concentric circles
  • concentric ellipse
  • straight line
  • square shape.
Electric motor is a device which converts
  • mechanical energy to electrical energy
  • electrical energy to mechanical energy
  • chemical energy to mechanical energy
  • mechanical energy to light energy.
The magnitude and direction of magnetic field produced by a straight current carrying wire at a given point depends on?
  • Current in the wire
  • Direction of the current
  • Distance of the point from the wire
  • All the above
which of these is incorrect  about magnetic lines of force?
  • A stronger magnetic field indicates magnetic lines of forces are closer
  • The magnetic lines of forces do not intersect one another
  • magnetic lines of forces originate from the north pole of a magnet and end at its south pole
  • none of these
which of these is true for electrical motor?
  • Converts electrical energy into mechanical energy
  • it works on principle of electromagnetic induction
  • converts mechanical energy into electrical energy
  • None of these
A copper wire can not used as fuse wire why?
  • it has high melting point
  • it offers low resistance
  • it is a good conductor of electricity
  • None of these
What  of these is true of electric generator?
  • it works on the principle of electromagnetic induction
  • converts mechanical energy into electrical energy
  • it can be used to produced both direct and alternating current
  • all the above
Force on a current conductor in a magnetic field depends on ?
  • Length of the conductor
  • Current in the conductor
  • Magnetic Field
  • All the above
which of these will not experience force in magnetic field?
  • Moving charge
  • Bar magnet
  • stationary charge
  • current carrying conductor
Two statement are made Statement A: Fleming left hand rule is used to determine the force on a current carrying conductor in magnetic field Statement B: Fleming right hand rule is used to determine the induced current for moving conductor in magnetic field Which of the below is correct option?
  • A is correct only
  • B is correct only
  • A and B both are correct
  • A and B both are incorrect
All the electrical appliances like fans and socket are connected in parallel across the live and neutral wire in the household circuit?
  • True
  • false
what is true about earth magnetism?
  • Earth is a huge electromagnet
  • Angle of dip at poles is 0°
  • The angle between magnetic meridian and geographic meridian at a place is called angle of dip
  • None of these
In electric fittings in a house
  • the earth wire goes through the switch
  • no wire goes through the switch
  • the neutral wire goes through the switch
  • the live wire goes through the switch
0 h : 0 m : 1 s

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