Shifts in the supply curve
Shifts in the supply curve are brought about by changes in factors other than the price of the commodity. A shift in supply is indicated by an entire movement (shift) of the supply curve to the right (downwards) or to the left (upwards) of the original curve.
When supply increases, the supply curve shifts to the right from S1S1 to S2S2. At price P1, supply increases from q1 to q'1 and at price P2 supply increases from q2 to q'2. Conversely, a fall in supply is indicated by a shift to the left or upwards of the supply curve and less is supplied at all prices. Thus, when supply falls, the supply curve shifts to the left from position S2S2 to position S1S1. At price p1, supply falls from q'1 to q1 and at price p2, supply falls from q'2 to q2.