as voltage transformation ratio. For an ideal transformer, Input power v p p i = Output power v s s i where i p and i s are the currents in the primary and secondary coil respectively. Therefore, v v s p s p p s ( . ) 12th - 12th - - - - - Unit ELECTROMAGNETIC INDUCTION AND ALTERNATING CURRENT power is lost due to Joule heating ( i R ) in the transmission lines which are hundreds of kilometer long.
This power loss can be tackled either by reducing current I or by reducing resistance R of the transmission lines. The resistance R can be reduced with thick wires of copper or aluminium. But this increases the cost of production of transmission lines and other related expenses. So this way of reducing power loss is not economically viable.
Step-up transformer Step-down transformer Transmission line City sub-station Power Station Figure . Long distance power transmissions Since power produced is alternating in nature, there is a way out. The most important property of alternating voltage that it can be stepped up and stepped down by using transformers could be exploited in reducing current and thereby reducing power losses to a greater extent. At the transmitting point, the voltage is increased and the corresponding current is decreased by using step-up transformer (Figure .
). Then it is transmitted through transmission lines. This reduced current at high voltage reaches the destination without any appreciable loss. At the receiving point, the voltage is decreased and the current is increased to appropriate values by using step-down transformer and then it is given to consumers.
Thus power transmission is done efficiently and economically. which some energy is lost in the form of heat. Hysteresis loss is minimized by using steel of high silicon content in making transformer core. Alternating magnetic flux in the core induces eddy currents in it.
Therefore there is energy loss due to the flow of eddy current, called eddy current loss which is minimized by using very thin laminations of transformer core. ii)