In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential V and then made to describe semicircular path of radius R using a magnetic field B. If V and B are kept constant, the \[ratio\,\left( \frac{ch\operatorname{arge}\,on\,the\,ion}{mass\,of\,the\,ion} \right)\] will be proportional to

• A. \[1/{{R}^{2}}\]
• B. \[{{R}^{2}}\]
• C. R
• D. \[1/R\]