Elementary charge the difference between the particle "electron" and the unit of charge "electron" was still blurred. Later, the name "electron" was assigned to the particle and the unit of charge "e" lost its name. However, the unit of energy electronvolt reminds us that the elementary charge was once called "electron". The maximum capacity of each pixel in a charge-coupled device image sensor, known as the "well depth", is typically given in units of electrons, commonly around 10 per pixel. In high-energy physics (HEP) Lorentz–Heaviside units are used, and the charge unit is a dependent one, formula_1, so that = 0.30282212088 .
Particle in a box which is proportional to formula_44. The variance in the position is a measure of the uncertainty in position of the particle: The probability density for finding a particle with a given momentum is derived from the wavefunction as formula_46. As with position, the probability density for finding the particle at a given momentum depends upon its state, and is given by where, again, formula_33. The expectation value for the momentum is then calculated to be zero, and the variance in the momentum is calculated to be: The uncertainties in position and momentum (formula_50 and formula_51) are defined as being equal