Question

If in the resultant wave the frequency and amplitude remains equals to amplitude of superimposing waves. Then phase diff. between them is: -

• A. $\frac{\pi }{6}$
• B. $\frac{2\pi }{3}$
• C. $\frac{\pi }{4}$
• D. $\frac{\pi }{3}$

Answer 1

The correct option is B $\frac{2\pi }{3}$

Superposition of waves does not alter the frequency of resultant wave and resultant amplitude

$a^2=a^2+a^2+{2a}^{2}cos\phi ={2a}^2(1+cos\phi )$

$cos\phi =-\frac{1}{2}=\frac{cos2\pi }{3}=\phi =\frac{2\pi }{3}$