Question

An electron is one of the most fundamental particles in nature. It is everywhere, in all the matter we can see, and it is with electrons that light interacts when it is emitted, absorbed, or scattered in everyday matter. The electron has a more massive cousin called a muon, also with a charge of -1 e, but with a mass of 1.88x10-28 kg. The electron's mass is 9.11x10-31 kg. You can see why a muon is called a "heavy" electron. A muon is also unstable, and left alone at rest in a lab it will turn into an electron, kinetic energy, and two neutrinos with a lifetime of 2.20x10-6 s.

1. Suppose we have a vacuum with two metal plates separated by 2 meters. One of the plates has a hole in it so that a charged particle coming from the other one can pass through into empty space. The plate with a hole is attached to a voltage source of 5,000,000 V and electrons and muons are introduced near the other plate at 0 V. What energies and velocities do the electrons and muons have when they pass through the hole?

2. If an electron or a muon encounters a magnetic field that is perpendicular to the line the particle is moving on, is their path changed? If so how does it depend on whether it is an electron or muon, and if not, why not?

3. Using an accelerator or some other natural phenomenon, suppose that you could observe a muon traveling through your lab at 0.999 times the speed of light. How long would it take to decay?

Answer 1