The mass-detecting part of a mass spectrometer is described below. Starting with basic equations, devise a mathematical expression for the particle mass. Description: An ion with mass m and charge +e leaves a velocity selector moving at speed v. It then moves in a half circle in a magnetic field that is perpendicular to the plane of its motion. At the end of this trip, it is detected. The radius of the circle can be used to determine the mass of the ion. Image: Indicate the direction of force. Equations: use Newton's second law to find an expression for mass