Is it permissible for a congregant who has an exam and fears missing it due to the Imam's lengthy Friday sermon to leave the sermon and go to another mosque, or to pray Dhuhr if he does not find another mosque?

If missing the exam entails worldly harm, then a person is permitted to leave the mosque to perform Jumu'ah (Friday prayer) in another mosque, or to pray Dhuhr (noon prayer) if they cannot catch Jumu'ah elsewhere. This is because fear of harm is an excuse that permits abstaining from Jumu'ah, similar to the case of a sick person or one who fears for their wealth or livelihood. However, if missing the exam does not entail harm, then it is not permissible to abandon Jumu'ah.