Question

Light wave travel in vacuum along the $x-$axis, which of the following may represent the wave front?

• A. $x=a$
• B. $y=a$
• C. $z=a$
• D. $x+y+z=a$

Answer 1

The correct option is A $x=a$

We know that the wave front is always perpendicular to the direction of propagation of light. Since the light is travelling along the $x-$axis, we can say that the wave front should be perpendicular to the $x$-axis.


Out of the given options only option $\left(\text{A}\right)$ satisfies the above condition.

Hence, option $\left(\text{A}\right)$ is the correct answer.

Concept :- Wavefront is always perpendicular to the direction of propagation of the wave.