Do internal noise like thermal noise in a system extract power from the DC supply?

Question

I have read that noises like thermal noises are due to high temperature causing random agitations in electrons etc.But one student was asking me that whether power is extracted from the DC source etc for generation of noise like thermal noise in circuits. I thought I will pose the question here.Do internal noise like thermal noise in a system extract power from the DC supply?

Answer 1

The theoretical answer would be NO.

For example, the thermally induced noise in the following circuit will not be drawn from the power supply:

^{simulate this circuit – Schematic created using CircuitLab}

In fact, you can measure a thermal noise even this way:

^{simulate this circuit}

However, it is rarely the case in modern circuits that the internally generated noise is not amplified. For example, in the following circuit the thermal noise of the resistor R can cause a power to be drawn from the power supply:

^{simulate this circuit}

Therefore the complete answer would be: it depends on the circuit in question.