Determine the total surface area of the leaves in cm 2 and record the value. Stepâ 2 Calculate the rate of transpiration/surface area. If you are using a gas pressure sensor to collect data, you can express these rate values as kPa/min/cm 2, where kPa (kilopascal) is a unit of pressure.Record the rate.etermine the total surface area of the leaves in cm 2 and record the value. Stepâ 2 Calculate the rate of transpiration/surface area. If you are using a gas pressure sensor to collect data, you can express these rate values as kPa/min/cm 2, where kPa (kilopascal) is a unit of pressure.
That's why cellphones are much more sophisticatedâand work in a completely different way. A cellphone handset contains a radio transmitter, for sending radio signals onward from the phone, and a radio receiver, for receiving incoming signals from other phones.
A Shifting Purpose. Early cell phones were just for talking. Gradually, features like voicemail were added, but the main purpose was talk. Eventually, cell phone manufacturers began to realize that they could integrate other technologies into their phone and expand its features.