In: Economics
Ans) Perfect competition is when there are many sellers selling homogeneous products. Firms are price takers because they have no control over deciding the price of the product. And since, no matter how much quantity they sell, they'll always receive same price, their marginal revenue is equal to price.
A real life example of price taker is vegetable market. Here, there are large number of sellers and every seller is selling same product (ie homogeneous products) and therefore, no firm has control over price. All the sellers sell vegetables at same price which is decided by forces of demand and supply.