6050
Radio waves were first produced deliberately by Heinrich Hertz in 1887 , using electrical circuits calculated to produce oscillations at a much lower frequency than that of visible light , following recipes for producing oscillating charges and currents suggested by Maxwell 's equations .
 person: Heinrich Hertz; person: Maxwell
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Heinrich Hertz, Maxwell 
Answer:
 person: Heinrich Hertz; person: Maxwell