Locating (physics) facts for kids

Locating something means finding exactly where it is. It's a key idea in physics and other sciences. To understand "location," we need to know how we figure out where things are.

What is Locating?

Locating is the process of finding the exact spot where something is. Think of it like giving directions to a friend. You tell them where to go from a known place. In science, we need very clear ways to describe a location.

Locating Big Things

When we want to find the location of large objects, like a ship or a hidden treasure, we usually start from places everyone knows. We then measure the distance and direction from those known spots.

For example, imagine you want to find Captain Smith's ship. You could use two famous landmarks, like Plymouth Rock and the Blarney Stone. You might say, "Captain Smith's ship is 1400 miles from Plymouth Rock, heading towards the Blarney Stone."

Another way to locate something is by using turns and distances. You could say, "Start at Plymouth Rock. Go 700 miles along a line towards the Blarney Stone. Then, turn 90 degrees to the left and go another 90 miles." This gives a very specific spot.

If you have a compass, it's even easier. You can use directions like north, south, east, and west. For instance, "Go three miles north of that big white rock. Then, go two miles east from that point. That's where the gold is hidden!"

How We Sense Location

We often find things by using our senses. We might see something in a certain place. We could hear a sound coming from a specific direction. Or we might feel something nearby.

Sometimes, we use tools to help us locate things. A photograph can show us where something was. Radar uses radio waves to find objects. Sonar uses sound waves, often to find things underwater.

Locating Tiny Things

Finding the location of very small things, like an electron or a photon, is much harder. These particles are incredibly tiny. The rules for finding them are different from finding big objects.

Finding a Photon

Imagine we want to find a single photon. A photon is a tiny packet of light energy. We could make a special light source that sends out only one photon at a time. We aim this light source at a piece of photographic film.

When the photon hits the film, it leaves a tiny mark. If the film is very sensitive, one photon can darken a tiny spot. This spot shows where the photon ended its journey. However, the mark is still much bigger than the photon itself. So, we know the photon was somewhere within that tiny spot.

When a photon hits something, like an electron, it gives all its energy to the electron and disappears. So, we only know where the photon was at the exact moment it stopped existing.

Photon's Path and Diffraction

Another way to try and locate a photon is to make it pass through a very small hole. We know when the light source sends out the photon. We also know the speed of light. This helps us guess when the photon should be passing through the hole.

We can try to get closer and closer to knowing its exact position in the middle of its flight. But there's a problem. When a photon goes through a tiny hole, its path becomes unpredictable. This is because of something called diffraction. Diffraction makes waves, like light, spread out after passing through a small opening. So, the photon's path becomes "wild" after it goes through the hole.