Q. Explain about Long run production function?

Long run is a phase adequately long so that all factors together with capital can be changed.

The factors that can be increased in the short run are known as variable factors, because they can be easily changed in a short period of time. Henceforth the level of production can be increased within the limits of existing plant capacity during the short run. So the short run production function proves that in short run the output can be increased by altering the variable factors, keeping fixed factors constant. Or we can say that in the short run output is produced with a given scale of production, which is, with a given size of plant. Behaviour of production in the short-run where output can be increased by increasing one variable factor keeping other factors fixed is known as law of variable proportions. Size of plant can be varied in the long run and, hence, the scale of production can be varied in the long run. Long run analysis of the laws of production is referred to as laws of returns to scale.