Licchavi Lyceum


Licchavi Lyceum

Maxwell Boltzmann Distribution Law

The Maxwell-Boltzmann distribution is a statistical distribution that describes the distribution of speeds or velocities of particles in a gas at a given temperature. It provides insights into the probabilities associated with different speeds and allows for the calculation of various properties of the gas, such as average speed and velocity distribution.

The distribution is derived based on the principles of statistical mechanics and assumes that the gas particles follow classical mechanics. It is applicable to an ideal gas or a dilute gas where the inter-particle interactions can be neglected.

The Maxwell-Boltzmann distribution is derived as follows:

  1. Consider a gas composed of a large number of identical particles moving independently in three dimensions.
  2. The distribution assumes that the particles’ speeds are distributed continuously, and there is a range of possible speeds.
  3. The distribution function, denoted as f(v), represents the probability density of finding a particle with a particular speed v.
  4. The Maxwell-Boltzmann distribution function is given by:

    f(v) = (m / (2πkT))^(3/2) * 4πv^2 * e^(-mv^2 / (2kT))


    • m is the mass of a gas particle
    • k is Boltzmann’s constant
    • T is the temperature of the gas in Kelvin
  5. The distribution function shows that the probability density is proportional to v^2 * e^(-mv^2 / (2kT)), indicating that lower speeds have a higher probability density, and the probability density decreases exponentially with increasing speed.
  6. The distribution is normalized, meaning that integrating the distribution function over all speeds will yield a probability of 1.

The Maxwell-Boltzmann distribution provides important insights into the behavior of gases. Some key properties and applications include:

  • Average Speed: The distribution can be used to calculate the average speed of the gas particles, which is given by:

    <v> = √(8kT / (πm))

  • Most Probable Speed: The speed at which the distribution function reaches its maximum value is known as the most probable speed (vmp). It can be found by taking the derivative of the distribution function with respect to v and setting it to zero. The most probable speed is given by:

    vmp = √(2kT / m)

  • Velocity Distribution: The distribution provides information about the probability density of finding particles within a specific speed range. By integrating the distribution function over a range of speeds, one can determine the fraction of particles within that range.
  • Applications: The Maxwell-Boltzmann distribution is utilized in various fields, including gas dynamics, kinetic theory of gases, and the design and analysis of gas-based technologies, such as gas mixtures, gas flow in pipes, and gas effusion.

The Maxwell-Boltzmann distribution provides a statistical description of the behavior of particles in a gas, allowing us to understand the distribution of speeds and calculate various properties associated with gas particles.

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