magnetic effect of electric current

• An electric current-carrying wire behaves like a magnet
• Electric current through a copper wire produces a magnetic effect
• Electricity and magnetism are linked phenomena
• Compass needle gets deflected when brought near a bar magnet
• Compass needle is a small bar magnet with north and south poles
• Like poles of magnets repel, while unlike poles attract
• Magnetic field is a quantity with direction and magnitude
• Compass needle moves in the direction of the magnetic field
• Magnetic field lines emerge from the north pole and merge at the south pole
• Magnetic field lines are closed curves and do not cross each other
• Magnetic field due to a current through a straight conductor
• Electric current through a metallic conductor produces a magnetic field around it
• Direction of the magnetic field is determined by the direction of the current
• Deflection of a compass needle changes with the direction of the current
• Magnetic field strength increases with an increase in current
• Magnetic field strength decreases as the distance from the conductor increases
• Convenient way to find the direction of the magnetic field associated with a current-carrying conductor
• Concentric circles around a straight conducting wire represent magnetic field lines
• Direction of the magnetic field lines can be found using a compass
• Magnetic field lines do not get reversed if the direction of current through the wire is reversed
• Right-hand thumb rule:

  • When holding a current-carrying straight conductor in your right hand with the thumb pointing towards the direction of the current, your fingers will wrap around the conductor in the direction of the field lines of the magnetic field
• Magnetic field due to a current through a circular loop:

  • The magnetic field produced by a current-carrying circular loop has concentric circles representing the magnetic field around it that become larger as you move away from the wire
  • At the center of the circular loop, the arcs of these big circles would appear as straight lines
  • Every point on the wire carrying current gives rise to the magnetic field appearing as straight lines at the center of the loop
• Magnetic field due to a current in a solenoid:

  • A solenoid is a coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder
  • The magnetic field lines around a current-carrying solenoid are in the form of parallel straight lines
  • One end of the solenoid behaves as a magnetic north pole, while the other behaves as the south pole
  • The magnetic field is uniform inside the solenoid
  • A strong magnetic field produced inside a solenoid can be used to magnetize a piece of magnetic material, like soft iron, when placed inside the coil
• Force on a current-carrying conductor in a magnetic field:

  • An electric current flowing through a conductor produces a magnetic field that exerts a force on a magnet placed nearby
  • The magnet exerts an equal and opposite force on the current-carrying conductor
  • The direction of force on the conductor depends on the direction of current and the direction of the magnetic field
  • Fleming’s left-hand rule can be used to find the direction of the force on the conductor
• • Devices that use current-carrying conductors and magnetic fields include electric motors, electric generators, loudspeakers, microphones, and measuring instruments
• Magnetism in medicine:

  • Weak ion currents in nerve cells produce magnetic fields
  • Magnetic Resonance Imaging (MRI) uses the magnetic field inside the body to obtain images for medical diagnosis
  • The magnetic field inside the body is significant in the heart and brain
• Fleming's left-hand rule is used to determine the direction of force on a current-carrying conductor in a magnetic field
• This can be achieved by moving a coil in a magnetic field or changing the magnetic field around it
• Most power stations produce AC, with a frequency of 50 Hz in India
• In domestic electric circuits, the main supply consists of live (positive) and neutral (negative) wires with a potential difference of 220 V
• Two separate circuits are used in homes: one with a 15 A current rating for high-power appliances, and the other with a 5 A current rating for lights and fans
• The earth wire, with green insulation, is connected to a metal plate deep in the earth near the house for safety
• Each appliance in a domestic circuit is connected parallel to ensure equal potential difference
• An electric fuse is used to prevent damage to appliances and circuits due to overloading or short-circuiting
• A compass needle has a north and south pole, and a magnetic field surrounds a magnet where the force can be detected
• A metallic wire carrying an electric current generates a magnetic field around it
• An electromagnet consists of a core of soft iron wrapped with a coil of insulated copper wire
• An electric motor converts electric energy into mechanical energy based on the force experienced by a current-carrying conductor in a magnetic field
• A generator converts mechanical energy into electrical energy through electromagnetic induction
• AC electric power in houses has a frequency of 50 Hz and a potential difference of 220 V