1. The problem statement, all variables and given/known data If all we know is that the media is 1.001, how can we compute the Cherenkov angle and threshold momentum of electrons,muons, pions, and kaons? 2. Relevant equations I know that cos(theta_c) = 1/beta*n, where beta = v_p/c and n=c/v_em, where v_p is the particle velocity and v_em is the velocity of the emitted wave. 3. The attempt at a solution The problem doesn't us what v_p and v_em is. It only tells us the value of n. How are we supposed to find the Cherenkov angle?