What points of the stretched string between the fixed points must be plucked and touched to excite its second harmonic ?

Where should a stretched wire, held between two fixed supports, be plucked and touched to excite its second harmonic ?

Where should a stretched wire, held between two fixed supports, be plucked and touched to excite its second harmonic ?

A second harmonic has to be generated in a string of length l stretched between two rigid supports. The point where the string has to be plucked and touched are

Where to pluck and where to touch a stretched string to excite its first overtone ?

Show that all harmonics are present on a stretched string between two rigid supports.