How is the optimal amount of labour determined in a perfectly competitive market?
In a perfectly competitive labour market, each firm takes the wage rate as given. The firm employs labour up to the point where the marginal revenue product of labour (MRP_L) equals the wage rate.
This equilibrium condition is expressed as w = VMP_L, where VMP_L is the Value of Marginal Product of Labour. Due to the law of diminishing marginal product, the marginal product of labour decreases as more labour is employed.
To maintain the equality between wage rate and VMP_L, the firm adjusts labour employment. At higher wages, less labour is demanded since VMP_L must increase, which requires employing less labour due to diminishing marginal productivity. Thus, the optimal amount of labour is determined at the point where the wage rate equals the marginal revenue product of labour.
Explanation
The textbook context clearly states that 'Each firm employs labour upto the point where the marginal revenue product of labour equals the wage rate.' This is the fundamental principle for determining optimal labour employment. The context also explains that under the law of diminishing marginal product, the condition w = VMP_L must be maintained, meaning firms adjust labour quantity based on wage rates.
Solution Steps
Step 1: Identify that firm takes wage rate as given in perfectly competitive labour market
Step 2: State the equilibrium condition: MRP_L = wage rate (or w = VMP_L)
Step 3: Explain how diminishing marginal product affects labour demand and optimal employment