Question

If the given two identical wave pulses are out of phase by ${180}^{\circ }$, then the resultant amplitude when they interfere at a point at the same line of motion is

• A. $0\text{cm}$
• B. $2\text{cm}$
• C. $4\text{cm}$
• D. $3\text{cm}$

Answer 1

The correct option is A $0\text{cm}$

The two given waves are out of phase by ${180}^{\circ }$
If we cosider the amplitude of wave $1$ as positive, the amplitude of wave $2$ will be negative.
So, at the point of interference, the resultant amplitude will be the vector sum of amplitudes, so, the magnitude of resultant amplitude will be
$2+(-2)=0\text{cm}$