Question

Consider a 1 nF capacitor is operated at the room temperature (20 °C).

a) What is the rms noise voltage that we should expect to measure across it, even in the absence of a signal?

b) What’s the theoretical limit of the energy required to charge this capacitor with a certain amount of electrical charge Q?

c) ( Following b), what’s the implication on computation

Answer 1

1) noise voltage across capacitor is induce due to thermal agitation

which is given by,

T=293K

so,

we get,

2) so theoritical limit to charge capacitor with any charge Q is,

so,

3) so this much amount of energy is already stored in capacitor so in order to charge capacitor with Q

weh have to cross this energy barrier.