Wave Propagation Through Materials

Why does Wi-Fi fade behind a concrete wall while light passes through glass? Why does a thin sheet of metal block radio but not sound? This simulator sends a wave from air into a slab of material and back out into air, and shows the three possible outcomes: part of the energy is reflected at the boundary, part is absorbed inside, and the rest is transmitted.

What you can do

• Switch between acoustic waves and electromagnetic waves.
• Choose from eleven materials: water, soft tissue, bone, glass, dry wood, concrete, brick, aluminum, copper, iron and lead.
• Sweep the frequency over many orders of magnitude — from infrasound to ultrasound, and from radio waves to X-rays and gamma rays.
• Change the slab thickness from 1 mm to 2 m and watch the energy bars respond.
• Read the wavelength in air and in the material, the impedance, the attenuation coefficient and the phase inside the slab.

Acoustics uses the acoustic impedance Z = ρc with multiple reflections inside the slab. Radio to optical waves use the complex impedance of a lossy dielectric or conductor, and very high frequencies switch to exponential photon attenuation. The material values are educational approximations.