1. What is Thermal Noise?

Thermal noise, also called Johnson-Nyquist noise, is the electronic noise generated by the thermal agitation of charge carriers inside an electrical conductor at equilibrium. It sets the fundamental lower limit on noise in electronic circuits.

2. How Does the Calculator Work?

The calculator uses the thermal noise power equation:

Where:

• \( P_n \) — Thermal noise power (W)
• \( k \) — Boltzmann constant (1.38064852 × 10^-23 J/K)
• \( T \) — Absolute temperature (K)
• \( B \) — Bandwidth (Hz)

Explanation: The equation shows that thermal noise power is directly proportional to both temperature and bandwidth.

3. Importance of Thermal Noise Calculation

Details: Understanding thermal noise is crucial for designing sensitive electronic systems, communication systems, and determining the fundamental limits of signal detection.

4. Using the Calculator

Tips: Enter temperature in Kelvin and bandwidth in Hertz. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the physical origin of thermal noise?
A: It results from the random motion of electrons due to thermal energy in conductors.

Q2: How does temperature affect thermal noise?
A: Noise power increases linearly with temperature - doubling the temperature doubles the noise power.

Q3: What is the relationship between noise power and bandwidth?
A: Noise power is directly proportional to bandwidth - wider bandwidth means more noise power.

Q4: Can thermal noise be eliminated?
A: No, it's a fundamental physical phenomenon, though it can be minimized by cooling systems.

Q5: What is the noise voltage equivalent?
A: For a resistor R, noise voltage is \( V_n = \sqrt{4kTBR} \).