Chapter Summary
Magnetic field is the region surrounding a magnet, in which the force of the magnet can be detected.
The path along which a hypothetical free north pole of a magnet tends to move is called field line.
The field lines around a straight wire are in the form of concentric circles.
Direction of field lines around a wire is given by Right Hand Thumb Rule.
If right thumb is kept straight with other fingers wrapped around, the thumb shows the direction of electric current and direction of other fingers shows the direction of magnetic field lines.
If electric current flows through a circular loop then magnetic field lines appear like rings around the rim of the loop.
Magnetic field lines get straighter as we move towards the centre of the loop.
A coil of many circular turns of insulated wire wrapped around a cylinder is called solenoid.
A solenoid behaves like a bar magnet.
If index finger, middle finger and thumb of left hand are kept perpendicular to each other then the index finger shows the direction of magnetic field, middle finger shows the direction of electric current and thumb shows the direction of force.
This rule shows the magnetic effect of a current-carrying conductor.
When an electric conductor and a magnet are in motion relative to each other then electric current is generated in the conductor. This effect is called electromagnetic induction.
If index finger, middle finger and thumb of right hand are kept perpendicular to each other then the index finger shows the direction of magnetic field, middle finger shows the direction of electric current and thumb shows the direction of force.
This rule governs electromagnetic induction.
Electric motor works on Fleming’s Left Hand Rule.
Electric generator works on Fleming’s Right Hand Rule.