A proton is projected with a velocity V_o towards a large sheet of charge having surface charge density $\mathrm{\sigma } \mathrm{coul}/{\mathrm{m}}^2$. From what distance should the proton be projected so that it just fails to strike the sheet of charge?

• A

  ${\in }_{\mathrm{o}}{\mathrm{mV}}_{\mathrm{o}}^2/4\mathrm{\sigma }$

• B

  $2{\in }_{\mathrm{o}}{\mathrm{mV}}_{\mathrm{o}}^2/\mathrm{\sigma }$

• C

  ${\in }_{\mathrm{o}}{\mathrm{mV}}_{\mathrm{o}}^2/\mathrm{\sigma }$

• D

  ${\in }_{\mathrm{o}}{\mathrm{mV}}_{\mathrm{o}}^2/2\mathrm{\sigma }$