What device is used to measure Latent Heat?

Latent heat refers to the amount of energy absorbed or released by a substance during a phase change, such as from liquid to vapor or vice versa, without a change in temperature. A sling psychrometer is specifically designed to measure humidity levels in the air by determining the difference in temperature between a wet bulb and a dry bulb. This difference is related to the moisture content in the air, which directly influences latent heat calculations.

The sling psychrometer provides indirect measurements that can be used to calculate latent heat involved in processes such as evaporation. When air has a high moisture content, less energy is required to change the state of water from liquid to vapor, hence impacting the assessment of latent heat.

In contrast, the other devices listed serve different primary purposes: a manometer measures pressure, mainly in fluids, a thermometer measures temperature, and a barometer measures atmospheric pressure. None of these devices relate directly to measuring latent heat or providing the necessary data to assess latent heat changes in the environment.

Thus, the sling psychrometer is the correct choice when discussing the measurement of latent heat due to its connection with humidity and moisture levels.