Signal Interference
Signal interference is when something blocks or weakens a signal as it travels from one place to another.
Two people talk at the same time in a kitchen. Their voices mix in the air between them. Where both voices rise together, the sound gets louder. Where one rises as the other falls, they cancel out and go quiet.
Explaining signal interference by grade level
Think about a radio playing music in your house. If you walk behind a thick brick wall, the sound gets quiet or fuzzy. The wall gets in the way of the radio waves. Some walls block more than others, and that changes what you hear.
Projects that explore signal interference
Signal interference happens when a barrier blocks or weakens a signal traveling between two devices. In this experiment, a transmitter sits behind different barriers while a car drives across a gymnasium floor. Wood caused the most interference, and brick caused the least. Each common building material blocks radio waves by a different amount.
A signal can also weaken from the path itself, not just an outside obstacle. Light travels through fiber optic cables by bouncing off the inner walls, but a tight bend lets some of that light escape. You wrap the cable around wooden dowels ranging from 1 inch to 1/8 inch in diameter, then record amplitude at each bend using a scopemeter. Tighter bends cause greater amplitude loss. The frequency stays the same — only the signal strength drops, and signals sent at a lower amplitude lose a higher percentage than those sent at a higher one.