The equation you are referring to is the de Broglie wavelength formula, which is given by:
λ = h / p
Where: λ is the de Broglie wavelength, h is Planck's constant (approximately 6.626 x 10^-34 joule-seconds), p is the momentum of the particle.
The de Broglie wavelength formula is used to determine the wavelength associated with a particle, such as an electron or a photon, which also exhibits wave-like properties. It relates the particle's momentum to its wavelength. This concept is an essential aspect of quantum mechanics and demonstrates the wave-particle duality of matter and energy.