What is use to measure heat intensity?

A thermometer is used to measure heat intensity, also known as temperature. Thermometers work by measuring the expansion or contraction of a substance, such as mercury or alcohol, in response to changes in temperature. The expansion or contraction of the substance causes a needle or indicator to move along a scale, indicating the temperature. Different types of thermometers may use different measurement scales, such as Celsius, Fahrenheit, or Kelvin.