Question

Why waves are always curved or spherical?

Answer 1

Wave motion is the disturbance travellers through a medium. As the medium is elastic in nature and the disturbance being handed from the one particle to the other particle, The extent of displacement of the particle from the mean position is different. There is a continuos variation like a sine wave because both sine wave and the wave in a medium ( like water wave ) are periodic in nature. That's why the curved. And it's propagation in all direction is in the form of the circular rings.