Kevin Zhou — USAPhO Practice B Problem 5 · Kevin Zhou #USAPhOB.5
Physics · electromagnetism
Problem
Consider a hollow tube with walls made of a neutral insulating material of length ℓ and
cross-sectional area A carrying an electric current I. The current is due to charged particles
of rest mass m and charge q distributed homogeneously inside the tube with number density
n. Assume that the charged particles are all moving along the tube with the same velocity.
Find the total momentum p of the charged particles in the tube, taking special relativistic
effects into account.