The time to cook corn varies depending on the size of the corn, its freshness and the way it is cooked. Here's a reference for how long it usually takes to cook corn:

1. To cook sweet corn: Bring lightly salted water (seasoned with a tablespoon of salt) to a boil, then add the husked sweet corn and reduce the heat to medium. Cook for 10 to 20 minutes, or until the corn is tender.

2. Cook raw corn: Place raw corn whole in boiling lightly salted water, keep the heat high, and cook for 10 minutes until cooked.

3. Steam the corn: bring the water to a boil, place the corn in a steamer basket, cover the pot, and steam for 15 to 20 minutes, or until the corn is tender.

It should be noted that the above times are for reference only. The actual time to cook the corn will also depend on the stove you are using and the size of the corn. It is recommended that you try a few times to find the perfect time to cook your corn.