Q. 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
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 $\frac{3l}{4}$
Explanation
(a) Second harmonic means 2 loops in a total length
Hence plucking distance from one end
$= \frac{l}{2p} = \frac{l}{2 \times 2} = \frac{l}{4}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.