Waves transfer energy without transferring matter. They spread from the source in concentric circles.

• Propagation speed depends on the medium
• Amplitude determines wave intensity
• Frequency remains constant during propagation

Diffraction is the ability of waves to bend around obstacles and pass through narrow gaps.

• More pronounced when the obstacle size is comparable to the wavelength
• The wave fans out after passing through a gap
• Explains how sound travels around corners

Interference is the superposition of waves from two coherent sources (Young's double-slit).

• Bright fringes represent constructive interference
• Dark fringes represent destructive interference
• The distance between fringes depends on the wavelength

Side view shows the wave profile — a sine wave moving through space.

• Amplitude is the maximum displacement from equilibrium
• Wavelength depends on frequency and speed
• The higher the frequency, the shorter the wavelength