1Two families of invisible signal
Some signals are light. Some are radio.
They're all invisible to your eyes, but they are not the same thing. One acts like a flashlight beam. The other acts like a ghost that walks through walls. Watch how differently they travel:
Light (a straight beam)
Infrared is really light — just a color your eyes can't see. Like a flashlight, it shoots out in a straight line and stops dead at anything solid.
Radio (a ghost wave)
WiFi and Bluetooth are radio — longer, lazier waves. They spread out in every direction and slip right through ordinary walls.
2Meet the three signals
Infrared, WiFi, and Bluetooth
The "flashlight beam"
It's light, so it travels in a straight line. You have to aim it at the TV, with nothing in the way — exactly like pointing a flashlight.
The "ghost that reaches far"
It's radio, so it goes through walls. And it shouts loudly, so it can reach across the whole house — no aiming needed.
The "ghost that stays close"
Also radio, so it goes through walls too — but it only whispers, on tiny power. It works through a wall, but only when the gadgets are close.
3Your turn — fire the signals
Tap the sender and watch all three fly
On the left is your sender (a remote/router/phone). On the right are the three gadgets. Tap Send a signal and watch the infrared beam, the WiFi ring, and the Bluetooth ring race across.
4Now close the door
Drop a wall in the way 🧱
Slide a wall right between the sender and the gadgets — like closing a door. One kind of signal will splat against it. The others will walk right through. But which?
Guess before you find out
You close the door between you and the gadgets. Infrared is light. WiFi and Bluetooth are radio. Which signals still get through the wall?
5So which one wins?
None of them! Each trades something
Needs aiming and a clear shot — a wall stops it cold.
Walks through walls and reaches the whole house.
Walks through walls too, on tiny power.
A remote points because infrared is light, and walls stop light. Your phone doesn't have to point because WiFi and Bluetooth are radio — and radio walks right through walls (WiFi the farthest, Bluetooth only nearby).
Psst, grown-ups: all three are electromagnetic waves at very different frequencies. Infrared sits just below visible light (~300 THz), so it behaves optically: line-of-sight, easily blocked, no diffraction around household objects. WiFi (~2.4/5 GHz) and Bluetooth (~2.4 GHz) are much lower-frequency radio with far longer wavelengths that diffract around and penetrate typical walls. Range is set by power and protocol: WiFi runs tens of mW up to ~100 mW for whole-home coverage, while Bluetooth Low Energy runs near 1 mW for short, low-power links.