Which type of wave has the medium moving back and forth at right angles to the direction the wave travels?

• A. Longitudinal wave
• B. Transverse wave
• C. Compressional wave
• D. Standing wave

Answer: (B)

This question tests how the direction of the medium’s vibration relates to the wave’s travel direction. When the medium moves back and forth at right angles to the direction the wave travels, the wave is transverse. The energy moves forward while the medium’s particles oscillate perpendicular to that forward direction, as seen in waves on a rope or on a string. In a longitudinal (compressional) wave, the particles move along the same line as the wave travels, not perpendicular. A standing wave describes a pattern formed by interference and isn’t defined by the medium’s motion being perpendicular to travel. So the described behavior is characteristic of a transverse wave.