The first cell phones were not exactly lightweight.
This one weighed around a kilogram – as heavy as a bag of sugar!
Thankfully, cell phones have come a long way since then!
Today, we use them to take photos, watch videos, play games, go online, listen to music, send messages, use apps… oh, and make calls!
Unless, of course, there’s no signal.
So here’s a curious question:
Why do cell phones lose signal?
Why do cell phones lose signal?
radio waves
Cells send and receive calls using radio waves.
These are the same kind of waves that send information to your radio and TV.
When you make a call, these invisible waves are sent out in all directions, and picked up by the nearest cell tower.
cell
The area covered by a tower is called a “cell” – which is why they’re known as “cell phones”!
The signal is then sent along a chain… until it reaches the other person’s cell.
However, radio waves can’t travel very far… so if there isn’t a tower nearby, there’s no signal either.
That’s why it’s harder to get signal in the countryside: there are fewer towers and they're more spread out, whereas in the middle of a town or city, there are loads of them!
But even if you are near a tower, you aren’t guaranteed a signal.
Thick barriers, such as walls, metal or rock, can block radio waves, which is why cell phones lose signal in tunnels… and elevators.
So, to make a call, your cell phone sends a signal to a tower.
But sometimes, there isn’t a tower nearby.
And even if there is, walls and other barriers can block the signal.
Got it? Great – another curious question answered!