Ryan Started the Fire!
I’m sure you’ve heard or read stories about how someone stranded on a distant, desolate island starts a fire using just their glasses to kickstart their survival hopes. Ever wondered how that actually works? Well, let’s figure it out!
Here’s a case to start us off: Our pal Ryan here, who wears glasses because of his hyperopia, has been suspected of a terrible arson on an otherwise beautiful summer day. Yikes. Michael, the senior detective on the case is sure Ryan started the fire, however, it’s a Monday morning and he’s feeling too lazy to explain why. So now we’re tasked to explain to the police how Ryan could’ve committed this crime.
To start, let’s take a quick look at hyperopia. What is it?
Hyperopia, or farsightedness, is a condition in which far away objects appear clear, but those that are closer are blurry. It is caused by either a shrink in the size of the eyeball or an extra-curved cornea (the transparent front layer of the eye). Because of this, the light rays reflected from an object being viewed are converging behind the retina (when the light rays converge, an image is perceived by our brains), instead of right on it as seen in the diagram above. The retina is like a light and colour sensor that tells our brain what we’re seeing by sending signals through the optical nerve. So when there is an issue with its ability to sense light properly, we should expect some vision troubles. To treat this, opticians prescribe convex, converging lenses which direct the rays towards each other even before entering the eye so that the image forms directly on the retina. Poof! Now you can see! I mean you also have glasses now, which isn’t ideal, but hooray for sight!
Great! Now we know how Ryan’s eye condition works. But how does his hyperopia correlate to him having the tools he needs to start a fire?
As we’ve learnt, the converging lenses used to treat hyperopia take almost parallel light rays and divert them towards each other. On a bright and hot summer day when the sun is beaming light with all its power, these glasses can get a bit… scary. Well, only if they’re used for mischievous purposes. You see, Ryan can use his glasses to focus the light from the sun at a very precise point. The concentration of energy at this point will soon generate enough heat to start a small fire. Then depending on how it’s handled, the fire grows. And grows. And now you’ve got a case of arson.
So, you explain the situation to the police and Ryan is rightfully charged. You get a pat on the back and Michael the senior detective is proud of you. That’s a pretty good day at work in my books.
