A free electron, with kinetic energy greater than the excitation energy of an isolated gas atom, collides with the atom and excites an orbiting electron to a higher energy level.
Which statement is correct?
The colliding electron must lose all of its kinetic energy to excite the atom.
The colliding electron must have had an initial kinetic energy exactly equal to the excitation energy of the atom.
The kinetic energy of the colliding electron decreases by an amount equal to the excitation energy of the transition.
The atom subsequently de-excites by emitting a photon with energy equal to the initial kinetic energy of the colliding electron.
31 exam-style questions on AQA A Level Physics Electromagnetic radiation and quantum phenomena, covering The photoelectric effect, Collisions of electrons with atoms, Energy levels and photon emission, and Wave-particle duality. Each one has a worked solution and a mark scheme showing where the marks go.