Question: you have a summer intern position at a laboratory that...
You have a summer intern position at a laboratory that uses a high-speed proton beam. The protons exit the machine at a speed of 2.2×106 m/s , and you've been asked to design a device to stop the protons safely. You know that protons will embed themselves in a metal target, but protons traveling faster than 2.4×105 m/s emit dangerous x rays when they hit. You decide to slow the protons to an acceptable speed, then let them hit a target. You take two metal plates, space them 2.0 cm apart, then drill a small hole through the center of one plate to let the proton beam enter. The opposite plate is the target in which the protons will embed themselves.
What are the minimum surface charge densities you need to place on each plate? σ = __C/m2