I've been studying about diodes and transistors and something made me wonder about the purpose of transistors.
In the examples we were talking about increasing current by using two batteries with a transistor and I understood how the transistor transfers the current from one side to another while increasing it with another battery connected to both sides(probably I still have gaps with my knowledge).
But the problem is: I didn't understand why we need transistor to increase current, can't we do the same thing by just connecting two batteries together or just using a transformator to increase voltage to get more current or just simply using a bigger battery?
Maybe I'm thinking so straight logic now but examples did not look satisfying to me to understand the usefulness of transistors as I know how widely they are used especially in computer science (which is I'm interested and planing to study in university.) so I would like to hear better examples with explanations.