1. At the end of a word when followed by a word that starts with a vowel sound or a "h" sound.
* Example:
* "صَفَة" (sifat) - "quality" + "الحَقِيقَة" (al-haqiqa) - "the truth" becomes "صِفَةُ الْحَقِيقَةِ" (sifatul-haqiqa) - "the quality of truth"
* Explanation: The ta marbuta becomes a "t" and then connects to the following vowel sound with the "u" sound.
2. In some grammatical constructions, especially with prepositions.
* Example:
* "مُسْلِمَة" (muslima) - "Muslim woman" + "لِ" (li) - "for" becomes "مُسْلِمَةٌ لِ" (muslimatu li) - "for a Muslim woman"
* Explanation: In this case, the ta marbuta is pronounced as a "t" and then merges with the preposition "li".
3. When followed by a certain set of letters called the "sun letters" (الشمسية, ash-shamsīyah).
* Sun Letters: These are: ت (t), ث (th), د (d), ذ (dh), ر (r), ز (z), س (s), ش (sh), ص (s), ض (d), ط (t), ظ (dh), ل (l), ن (n).
* Example:
* "رَجُلَة" (rajula) - "woman" + "الْحَقّ" (al-haqq) - "the right" becomes "رَجُلَةُ الْحَقّ" (rajulatu l-haqq) - "the woman of right"
* Explanation: The ta marbuta merges with the following sun letter "l" and is pronounced as a "t" sound.
Important Note: The ta marbuta does not change to a "t" sound in all cases. In many instances, it remains as a silent "h" sound or is pronounced as "a".
Understanding the different cases when ta marbuta changes to a "t" sound requires a good understanding of Arabic grammar and phonetics.