the evaporation off the moisture on the wet bulb absorbs the heat.

wet bulb temparature will increases

for air water system wet bulb equals to dry bulb at 100 % relative humidity for that given temperature of air.

A wet bulb measures the temperature after water evaporation allows to cool and a dry bulb measures air temperature.

the "current" temperature, ie, the temperature at which wet bulb and dry bulb are the same. when the wet bulb and dry bulb temperaturs equalized the dew point emperature equals them, because the air is saturated now.