Transformer Assignment - Essay Example

A simple way to remember it is the Left Hand Thumb rule. If we grasp the conductor in our left hand with our thumb extended in the direction of current (from –ve to +ve), our finger will point in the direction of magnetic lines of forces. When two or more current carrying conductors are placed parallel to each other in a way that the direction of current is the same in all of them, as shown in Figure 2, then the magnetic lines of forces aid each other to combine and strengthen the magnetic field further.

If the two conductors so placed have current flowing in opposite direction then the magnetic lines oppose each other to deform and weaken the magnetic field. The magnetic field around the conductor exists at points along the length of the conductor. When the conductor is wound in the shape of a coil, as in Figure 3, then magnetic field around each turn of the coil is aided and strengthened by the fields of adjacent turns in the coil. The resultant is a magnetic field resembling a bar magnet with one end as North and the other as South of the magnet.

When the direction of current is reversed it causes the direction of magnetic field to be reversed. If we grasp the coil with our left hand with our fingers pointing in the direction of current, as in Figure 4, the thumb will point in the direction of magnetic field. Conversely, to what we have discussed till now, if a conductor is placed in a magnetic field and there is a relative movement between the field and the conductor, an electromotive force (emf) is induced in the conductor. This effect is called electromagnetic induction.

Both of these phenomenons, of creating a magnetic field and then utilizing electromagnetic induction form the basis of transformers. At one end alternating current (AC) is passed through a coil, this gives rise to a magnetic field which spreads out and subsides with the same frequency as of the AC applied. This changing magnetic field in fact is a replacement to moving