Equilibrium Exchange Rate:

The theory of exchange rate determination explains how demand and supply of foreignexchange interact and jointly determine the equilibrium exchange rate. 

As seen earlier, the demand schedule for Indian rupees (or supply schedule of foreigncurrency) arises from the foreign demand for Indian exports. Similarly, the supplyschedule of Indian rupees (or demand schedule for foreign currency) arises from theIndian demand for foreign goods or imports. Together, they determine the equilibriumexchange rate (R*)Suppose there is an exogenous increase in income in the US and therefore an increasein demand for Indian goods.  Correspondingly, the demand schedule for Indian rupeesshifts to D₁.  The resultant equilibrium exchange rate (R*₁ ) indicatesthat the Rupee has appreciated against the dollar.  

Similarly, if Indian imports increase(relative to the exports) then the supply curve (SRs) shifts to the right resulting in the depreciation of Indian rupee from R2 to (R*₁).Thus, in a flexible exchange rate regime, market demand for and supply of a country'scurrency determines the changes in exchange rate.  As the demand and supply schedules for currency are determined by many forces, there would be a tendency for high volatilityof exchange rates in this regime. As there would be no intervention by the CentralBank in determining the exchange rate, the BoP will always be in equilibrium. It meansthat the exchange rate adjusts to make the balances in current and capital accounts sumto zero.