Which two tectonic plates are separated by the midocean ridge?

The mid ocean ridge separates many plates, not just two. In the Atlantic Ocean it separates the Eurasian and African plates from the North American Plate and the African Plate from the South American Plate. In the Indian ocean it separates the African Plate from the Antarctic, Australian, Indian Plates and the Australian Plate from the Antarctic Plate. In the Red Sea it separates the African Plate from the Arabian Plate. In the Pacific Ocean it separates the Pacific Plate from the Antarctic, Nazca, Cocos, and Juan de Fuca Plates and the Nazca Plate from the Cocos and Antarctic Plates.