Q. Two sinusoidal waves with same wavelengths and amplitudes travel in opposite directions along a string with a speed $10\ ms^{- 1}.$ If the minimum time interval between two instants when the string is flat is $0.5s$, the wavelength of the waves is
A) $25\ m$
B) $20\ m$
C) $15\ m$
D) $10\ m$
Explanation
(d) Minimum time interval between two instants when the string is flat
$= T/2 = 0.5\ \sec \Rightarrow T = 1\ \sec$
Hence $\lambda = v \times T = 10 \times 1 = 10\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.