In mass spectrometer, detector or collector measures the:

Explanation

Mass spectrometers measure the relative abundances of isotopes of an element. Mass spectrometers are analytical instruments used to measure the mass-to-charge ratio of ions. One of the key applications of mass spectrometry is determining the relative abundances of isotopes in a sample. The basic principle involves ionizing a sample, then separating and detecting ions based on their mass-to-charge ratio. Since isotopes of an element have different masses, the mass spectrometer can distinguish between them, allowing scientists to determine the relative abundance of each isotope in a given sample.