(numbers . When two closed tubes (closed at one end) of different lengths each resonate at their 5th harmonic, a 5 Hz beat frequency is observed. , . If one tube has length L, at which distance from the open end is a displacement node found? a) L/5 b) 2L/5 c) 3L/5 d) L e) more than one of the above answers are correct Both tubes are now ogened at both ends. When each tube now resonates at its 2nd harmonic frequency, what beat frequency is observed? a) 2 Hz b) 4 Hz c) 6 Hz d) 8 Hz e) more information is needed to determine