PLEASE HELP : electric current from the power station is carried by transmission lines to a substation and then distributed at a lower voltage to a transformer near a home. the transformers output connected to the homes A:service entrance
B:step up transformer
C:branch circuit
D:residential transformer

Precipitation hardening can be achieved in many light alloys by a three-step heat treatment. what is carried out and what is the purpose at each step? why is such a treatment necessary based on the nucleation and growth theory of phase transformation. compare this treatment with tempering martensite for carbon steels (similarities and differences).