Magnetic Effect of Electric Current: Electromagnetic Induction

These notes are based on the chapter Magnetic Effect of Electric current class 10 science NCERT book and CBSE syllabus.

Michael Faraday, an English Physicist is supposed to have studied the generation of electric current using magnetic field and a conductor.

In his first experimental demonstration (August 29, 1831), Faraday wrapped two wires around opposite sides of an iron ring. He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. When electric current passed through one wire, electric current was produced in another wire and could be detected by the galvanometer.

In another experiement, Faraday quickly slid a bar magnet in and out of a coil of wires. He could observe induction of electric current in the wire.

When a conductor is set to move inside a magnetic field or a magnetic field is set to be changing around a conductor, electric current is induced in the conductor. This is just opposite to the exertion of force by a current carrying conductor inside a magnetic field. In other words, when a conductor is brought in relative motion vis-à-vis a magnetic field, a potential difference is induced in it. This is known as electromagnetic induction.

Fleming's Right Hand Rule

Electromagnetic induction can be explained with the help of Fleming's Right Hand Rule.

If the right hand is stretched in a way that the index finger, middle finger and thumb are in mutually perpendicular directions then

the thumb shows the direction of movement of the conductor
index finger shows the direction of magnetic field and
the middle finger shows the direction of induced current in the conductor.

The directions of movement of conductor, magnetic field and induced current can be compared to three mutually perpendicular axes, i.e. x, y and z axes.

The mutually perpendicular directions also point to an important fact that the when the magnetic field and movement of conductor are perpendicular, the magnitude of induced current would be maximum.

Many of you may find it difficult to remember Fleming's Left Hand Rule or Right Hand Rule, because it can be quite confusing to correlate different fingers with different forces. What is common in both the rules is correlation between a particular finger and a particular force. In both the cases, index finger always shows the magnetic field. Middle finger always shows electric current and the thumb always shows the direction of motion.

Electromagnetic induction is used in the conversion of kinetic energy into electrical energy. Electric generator works on the principle of Fleming's Right Hand Rule.