As-salam-o-Alaikum...
The two of the similar nature( mutajanisaan)
Do we make a qalqalah of the letter (ta) in the word far-ratana (Surah- al-Anaam ayat 38)or will the itbaq remain ?
Thank you for answering my previous questions..
May Allah reward you all for your hard work.. Ameen.
Answer
Wa alaikum assalaam wa rahmatullahi wa barakatuh,
In the word
there is a 
with a shaddah followed by the 
letter . The and the , do not share the same articulation points, so there is no possibillty of idghaam mutajanisayn. The has a shaddah, and a letter with a shaddah cannot merge into a letter with a sukoon. It is always the letter with the sukoon (no vowel) that merges into the following vowled letter, and this second letter obtains a shaddah as a result of the idhgaam. In the case of an incomplete idghaam, there is no shaddah on the second letter, but the letter precedes it has a sukoon. The is read with a qalqalah and with all of its characteristics, including 
.There are examples in the Qur'an in which a saakin letter
merges into the letter 
, and this is an incomplete merging. One example of this is in: 
. When this idghaam occurs, the merges incompletely into the . There is the characteristic of which remains left over from the , but no other characteristic from the letter remains. There is no qalqalah on the in this case, as the has merged into the next letter, with only remaining left, nothing else. Another example of this type of incomplete merging of the
into the is in: 
, to listen to this aayah read, please click on the following here.We apolgize, as we just noticed some of the lessons of idghaam did not make it to the new site design. To see the rest of the lessons, please go to the following link (old site design): http://www.abouttajweed.com/al-mutamathilayn_al-mutajaanisayn_4.htm and http://www.abouttajweed.com/the_lessons_on_letter_relationships.htm
May Allah reward you and increase you in beneficial knowledge.
Wa assalaam alaikum wa rahmatullah.