Smartphones are used more frequently for watching videos than ever before, but sometimes you just want a bigger viewing area. For those strapped for cash or in the mood to do something creative, you can construct your own homemade projector. All the project takes is a cardboard box, a smartphone, and a few basic tools. The result is a real, working projector!
On one of the ‘short’ ends of the box, trace around the magnifying glass. Use the utility knife to cut the traced circle out of the box. Bend a paper-clip into a stand for your smartphone (you’ll have to get a bit creative here). Attach the stand to the opposite end of the cut hole.
Tape the magnifying glass over the hole you previously cut out. Set your screen to a landscape orientation. Place your phone upside down with a video playing into the box. Seal the box with packing tape. Turn off all the lights, grab a snack, and enjoy the show!
How does it work? Let’s start with your upside-down phone. Have you ever heard that we actually see our world upside down? Well, the homemade projector can help visualise this concept. The human eye has a lens much like the magnifying glass attached to your projector. The lens flips the image through refracting the light from the phone’s screen just like your eye does the light from the world.
While our brain knows to flip the image back to its correct orientation, the wall doesn’t. That’s why you have to set your phone in the box upside down.
But how about that screen? It’s way bigger than the magnifying glass lens! This works because of the shape of the lens: convex. A convex lens has a shape where the sides bend outwards, rather than inwards like a concave lens. The shape of a convex lens allows it to catch, bend, and focus more space from inside of the box.
Once you create an atmosphere dark enough by turning off all the lights, the magnifying glass will gather and focus all the light it can from the box. The result is your homemade projector!
For other fun experiments visit: www.stevespanglerscience.com.