What are two ways alternating currents are similiar? 1. in both ac and dc, the flow of electrons changes directions back and forth. 2. both ac and dc involve the flow of electrons. 3. both ac and dc are only possible in certain materials with atoms that will allow electron flow. 4. in both ac and dc electrons flow in the same pattern.

AC stands for alternating current (current flows in both directions) and DC stands for direct current (current flows in one direction).

I would say 2. and 3. are correct because 1. states that current flows in both directions for AC and DC, and we just said that was false, and 4. says that they have the same flow patter, which is basically what we said was false about 1.