We all are aware of revolutionary technology – visa debit and credit cards. Now similar cards are flooding the market. We swipe our card through the card swiping machine or card reader and our transaction is done. Super cool technology! Isn’t it? But have you ever wondered what is the technology used behind it? We all might have seen a black strip at the back of the card. This is a magnetic strip which produces electromagnetic induction and card reader uses this to determine the card details. Sounds interesting?
HISTORY AND DEFINITION
In 1831, Michael Faraday came up with this theory and formulated Faraday’s laws of induction. Electromagnetic Induction can be defined as is a process in which a conductor is placed in a changing magnetic field or a conductor is moved across a stationary magnetic field to produce potential or voltage difference across two ends of a conductor. This potential difference stops when the conductor stops moving. Faraday used coil of wire as conductor and a magnet.
PRINCIPLES OF ELECTROMAGNETIC INDUCTION
There are 2 principles that determine how much voltage (or potential difference) is generated in the conductor. Firstly, the amount of voltage produced is directly proportional to the surface area of wire exposed to the magnetic field. That is, more number of coils in the wire, means more surface area exposed, means more voltage produced. Therefore, number of turns in the wire is the major aspect. If you triple the number of turns, the induced voltage triples in magnitude.
The second principle states that, rate at which the magnetic field is changing effects the induced voltage. If there is a relative motion between the coil and the magnet (which ever direction it is), the induced voltage increase. If electromagnet is getting used, we can vary the strength if the current or magnetic field produced simply by switching on or off the magnet. Therefore, one major key that comes into highlight is voltage is not introduced just by holding a magnet near to the conductor. Motion is necessary.
APPLICATIONS OF ELECTROMAGNETIC INDUCTION
Electromagnetic Induction is used in transformers that deliver current to our houses. It is based on two principles. Firstly, electric current produces magnetic field which is called electromagnetism. Secondly, varying magnetic field produces voltage across the conductors. This induced potential difference is used to transfer current (from higher potential to lower potential).