A sample containing 12c, 160, and an unknown isotope is analyzed in a mass spectrometer. As in the figure, the ions move around a semicircle before striking a photographic plate. The 12ct and 160+ ions are separated by 7.820 cm on the plate, and the unknown isotope strikes the plate 4.820 cm from the 12Ctions. What is the mass of the unknown element? Uniform B between poles of magnet Ion Ions all source have same KE Low-speed ions Photographic plate or other detector AV Accelerating potential U