What is the expiation for having intercourse with one's wife during the daytime in Ramadan while traveling, knowing that the husband is traveling and not fasting, while the wife is a resident and fasting, and upon whom is the expiation incumbent?

A traveler who arrives at his place of residence during the day is not required to abstain from eating and drinking, nor is he required to offer expiation (kaffarah) if he has intercourse with his wife. However, he is sinful for invalidating her fast. As for his wife, she is not required to offer expiation, but she must make up the missed fast (qada'). If she were to offer expiation, it would be more prudent for her.