text: When this quantity becomes very large, the reflection coefficient becomes greater than one, according to the Klein paradox.
full_question: When this quantity becomes very large, the reflection coefficient becomes greater than one, according to the Klein paradox. The Fourier transform of this quantity gives the first-order scattering amplitude according to the Born approximation. When this quantity is proportional to a delta function, the system possesses a continuum of sinusoidal scattering states with positive energy and a single bound state with negative energy. This quantity is infinite inside of a critical radius and zero outside that radius according to the hard sphere model. This quantity is subtracted in the Lagrangian but added in the Hamiltonian. This quantity is infinite everywhere except for between 0 and L in the infinite square well or particle-in-a-box model. For 10 points, name this type of energy equal to "m g h" for an object near the earth, which is symbolized V or U.
first_sentence: When this quantity becomes very large, the reflection coefficient becomes greater than one, according to the Klein paradox.
raw_answer: potential energy [or U or V until they are read; or gravitational potential energy; or electric potential energy]