question_answer

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  [KCET 2001]

A)            Plucked at \[\frac{l}{4}\] and touch at \[\frac{l}{2}\]

B)            Plucked at \[\frac{l}{4}\] and touch at \[\frac{3l}{4}\]

C)            Plucked at \[\frac{l}{2}\] and touched at \[\frac{l}{4}\]

D)            Plucked at \[\frac{l}{2}\] and touched at \[\frac{3l}{4}\]

Correct Answer: A

Solution :

                     Second harmonic means 2 loops in a total length Hence plucking distance from one end \[=\frac{l}{2p}=\frac{l}{2\times 2}=\frac{l}{4}.\]