Physics - Wave Optics Question with Solution | TestHub

A wavefront is defined as the continuous locus of all particles of a medium which are vibrating in the same phase.

According to Huygens' principle, the direction of propagation of light (a light ray) is always perpendicular to the wavefront at any given point.

Therefore, a wavefront is a surface that is perpendicular to the direction of propagation of light.

Answer: perpendicular to the direction of propagation of light.