Transverse Waves

How does light move?

This device demonstrates the propagation of transverse waves—waves that "wiggle" perpendicular to the direction they travel. You may notice their speed doesn’t depend on their amplitude (smaller vs. larger pulses) or frequency (slower vs. faster shaking). 

Light is a transverse wave too, but the "wiggling" is done by perpendicular electric and magnetic fields (Figure e). Light is unique in that it doesn’t require a medium to travel. In fact, it travels fastest through empty space, moving at roughly 300,000,000 m/s (670,000,000 mph). Thanks to this blinding speed, the light and heat from the Sun reaches us from 93,000,000 miles away in about 8 minutes.

The patterns in Figures ad are known as standing wavesbecause they appear to stop moving horizontally, instead just vibrating up and down. They are created by the  waves you generate overlapping with the waves reflecting at the other end of the  device. Standing waves can only form at certain frequencies, known as the natural frequencies of the device.

Standing waves of light are used in microwave cooking, lasers, microscopic imaging, and electronic communications.