Consider the following three particles: Rank them according to the wavelengths of their waves, least to greatest.
A) 1, 2, 3
B) 3, 2, 1
C) 2, 3, 1
D) 1, 3, 2
E) 1, then 2 and 3 tied

Question

Consider the following three particles:  Rank them according to the wavelengths of their waves, least to greatest.
A) 1, 2, 3 
B) 3, 2, 1 
C) 2, 3, 1 
D) 1, 3, 2 
E) 1, then 2 and 3 tied

Quizplus · Accepted Answer

The wavelength of waves is inversely proportional to the particle's momentum, so the particle with the highest momentum will have the shortest wavelength. 
Particle 1 is an electron, with the least momentum of the three, so it has the longest wavelength. 
Particle 2 is a proton, which is heavier than an electron, so it has a shorter wavelength than Particle 1. 
Particle 3 is a photon, which has no rest mass, and therefore the highest momentum of the three particles, resulting in the shortest wavelength. Hence, the correct order of the particles from least to greatest wavelength is Particle 1 (electron), Particle 2 (proton), Particle 3 (photon), which is option B.

Consider the Following Three Particles: Rank Them According to the Wavelengths