Videotape Compass – one minute survival tip
How to improvise a compass from a video tape.
Today’s magnetic tape is composed of three main layers: the base film, the magnetic layer, and the back coating. The base film provides the physical support and main strength of the tape. The magnetic layer determines the tape’s magnetic properties. It is composed of magnetic powders, ranging from lower strength iron oxides to high-energy metal particles, that determine the tape’s magnetic properties.
The magnetic particles that coat a videotape are needle-shaped. This allows them to be tightly packed onto the tape surface. The greater the magnetic density, the better the tape. The best tapes use smaller particles packed in greater concentration.
This is in a nutshell the reason why a video tape can be used as a compass needle.