This is a general question. Suppose I have a circuit like below from CircuitDigest:
My supervisor said that about the circuit that..
[The] circuit does actually involve an amplifier, even though it’s not super obvious: the noisy current in the Zener diode is amplified by the transistor, and R1 effectively converts current fluctuations into voltage fluctuations.
I had no idea it involves an amplifier - I don’t see one here. I see a transistor only. He also says the resistors effectively converts current fluctuations and voltage fluctuations.
What can I read to be able to make deductions such as this? Any recommendations (textbooks and the like) would be appreciated, as well as any useful links.