How is the activity of a radioactive substance measured?

The activity of a radioactive substance is measured using a Geiger-Muller tube and a counter.

Radioactivity is the process by which unstable atomic nuclei emit particles or electromagnetic waves. The activity of a radioactive substance is the rate at which it emits radiation. This activity can be measured using a Geiger-Muller tube and a counter.

A Geiger-Muller tube is a device that detects ionizing radiation. It contains a gas-filled chamber with an electrode at each end. When radiation enters the chamber, it ionizes the gas, creating a current that can be detected by the electrodes. The counter is used to measure the rate at which the current is produced.

To measure the activity of a radioactive substance, the substance is placed near the Geiger-Muller tube. The tube detects the radiation emitted by the substance and produces a current. The counter measures the rate at which the current is produced, which is proportional to the activity of the substance.

The activity of a radioactive substance is measured in becquerels (Bq), which is the number of radioactive decays per second. One becquerel is equal to one decay per second. The activity of a substance can also be measured in curies (Ci), which is an older unit of measurement. One curie is equal to 3.7 x 10^10 becquerels.

In summary, the activity of a radioactive substance is measured using a Geiger-Muller tube and a counter. The rate at which the tube produces a current is proportional to the activity of the substance, which is measured in becquerels or curies.