Question

Internal threads are determined by what letter?
1) A
2) B
3) C
4) D

Answer 1

The letter that determines internal threads is B. This letter refers to a certain thread series used for specific applications.

Step-by-step explanation:

The letter that determines internal threads is B.

In the context of threads, the letter B refers to a certain thread series. Thread series are standardized thread forms used for specific applications. The most common thread series for internal threads is the Unified National Coarse (UNC) series, which is identified by the letter B.

For example, if you see a designation like 1/4-20UNC, the letter B indicates that the internal thread follows the UNC series and has a diameter of 1/4 inch and a pitch of 20 threads per inch.