Question

Two interfering waves have the same wavelength, frequency and amplitude. They are travelling in the same direction but ${90}^{\circ }$ out of phase compared to individual waves. The resultant wave will have the same

• A. amplitude and velocity but different wavelength
• B. frequency and velocity but different wavelength
• C. wavelength and velocity but different amplitude
• D. amplitude and frequency but different wavelength

Answer 1

The correct option is C wavelength and velocity but different amplitude

Wavelength and velocity are medium dependent, hence same for same medium.

Final amplitude is decided by the superposition of individual amplitudes.

$A_r=\sqrt{A_1^2+A_2^2+2A_1{A}_2\cos \varphi }$
Given $A_1=A_2=A,\varphi ={90}^{\circ }$
$A_r=\sqrt{2}A$