1. The problem statement, all variables and given/known data A beam of particles of energy E = 9 eV strikes on a step potential and 25% of the beam's particles is reflected back. What is the height of the step potential? (A) 4 eV (B) 8 eV (C) 3 eV (D) 1 eV (E) 5 eV 2. Relevant equations √(R) = [√(E)-√(E-U)]/[√(E)-√(E_U)] 3. The attempt at a solution Just plug and chug the equation I have, but this is for a timed test without a calculator or equation sheet. This seems clunky to remember, solve and do in such conditions. Is there a simpler way? I get 8eV, which is the correct answer.