Figure (15-E10) shows an aluminium wire of length 60 cm joined to the steel wire of length 80 cm and stretched between two fixed supports. The tension produced is 40 N. The cross-sectional area of the steel wire is 10 mm2 and that of the aluminium wire is 30 mm2. What could be the minimum frequency of a tuning fork which can produce standing waves in the system with joint as a node? The density of aluminium is 26 cm−3 and that of steel is 7.8 g cm−3.
180 Hz
We know that, 
So, 
Similarly, 
Now, 
By, putting T=40 and m=
We get that,
If frequency is minimum, wavelength should be maximum and no of loops should be minimum.
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