To fully cook rice in the Microwave it takes at least 15 minutes.
Put the rice in a microwave safe bowl and then fill it with water to cover the rice and cook the rice in the microwave until all the water is absorbed and the rice becomes tender which usually takes 15 minutes.
If not put a little more water on the rice and cook for a few more minutes.
Once the rice becomes tender then it's done and ready to eat.