Explain the concept of Inflationary Gap. Explain the role of Repo Rate in reducing this gap.
OR
Explain the concept of Deflationary Gap and the role of 'Open Market Operations' in reducing this gap.

Inflationary gap is also referred to as excess demand. When aggregate demand is greater than aggregate supply, at full employment level in the economy, it is referred to as inflationary gap or excess demand. This situation actually results in an increase of prices, that is inflation.
Graphically, it is represented by the vertical distance between the actual level of aggregate demand (ADE) and the full employment level of output (ADF).

In the figure, EY denotes the aggregate demand at the full employment level of output and FY denotes the actual aggregate demand. The vertical distance between these two represents inflationary gap. That is,
FY – EY = FE (Inflationary Gap)
In the figure, AD₁ and AS represent the aggregate demand curve and aggregate supply
curve respectively. The economy is at full employment equilibrium at point “E”, where AD₁ intersects AS curve. At this equilibrium point, OY represents full employment level and EY is aggregate demand at the full employment level of output.
Suppose that the actual aggregate demand for output is FY, which is higher than EY. This implies that actual aggregate output demanded by the economy FY is more than the potential (full employment) aggregate output EY. Thus, the economy is facing surplus demand. This situation is termed as excess demand. As a result of the excess demand, inflationary gap arises. The inflationary gap is measured by the vertical distance between the actual aggregate demand for output and the potential (or full employment level) aggregate demand. In other words, the distance between FY and EY, i.e. FE represents the inflationary gap.
Repo rate refers to the rate at which the central bank lends to the commercial bank. In case of inflationary gap, the central bank would increase repo rate. An increase in the repo rate increases the cost of borrowings for the commercial banks. This discourages the demand for loans and borrowings. Thereby, the consumption expenditure falls, and hence aggregate demand falls.
Or

Deflationary gap is otherwise called as deficit demand. It is a situation where aggregate demand is less than aggregate supply at the level of full employment. Graphically, it is represented by the vertical distance between the aggregate demand at the full employment level of output (ADF) and the actual level of aggregate demand (ADE). In the figure below, EY denotes the aggregate demand at full employment level of output and CY denotes the actual aggregate demand. The vertical distance between these two represents deflationary gap.

EY – CY = EC (Deflationary Gap)
In the figure, AD₁ and AS represent the aggregate demand curve and aggregate supply curve. The economy is at full employment equilibrium at point “E”, where AD₁ intersects at AS curve. At this equilibrium point, OY represents the full employment level of output and EY is the aggregate demand at the full employment level of output.
Let us suppose that the actual aggregate demand for output is only CY, which is lower than EY. This implies that actual aggregate output demanded by the economy CY falls short of the potential (full-employment) aggregate output EY. Thus, the economy is facing a deficiency in demand. This situation is termed as deficit demand. As a result of the deficit demand, deflationary gap arises. The deflationary gap is measured by the vertical distance between the potential (or full employment level) aggregate demand and the actual aggregate demand for output. In other words, the distance between EY and CY,
i.e. EC represents the deflationary gap.
To correct deflationary gap, the central bank purchases the securities in the market through Open market operations (OMO). It refers to the buying and selling of government securities in the open market in order to expand or contract the amount of money in the banking system. Through OMO, the flow of money is increased and subsequently enhancing the purchasing power of the people. The higher purchasing power increases the aggregate demand.