Hooked on Science: The reversing arrow

Did you know you can change the direction of an arrow just by using water?

Materials

* Transparent glass

* Black permanent marker

* Piece of paper

* Water

Instructions

STEP 1: Fill the transparent glass with water.

STEP 2: Using the black permanent marker, draw a horizontal arrow on the piece of paper.

STEP 3: Place the piece of paper with the horizontal arrow behind the transparent glass of water. Make sure the paper is touching the glass and observe the horizontal arrow.

STEP 4: Move the piece of paper with the arrow away from the glass of water and observe the arrow.

Explantation

As the paper with the arrow is moved away from the glass of water, the arrow appears to reverse. Light travels in a straight line until it hits an object. Then, the light may reflect or bounce off the object, refract or pass through the object, or absorb or get caught by the object. The light is refracted as it passes through the glass, the water, then through the back of the glass, and finally through the air to the paper with the arrow. This refraction causes the arrow to appear as if it is reversed.

Jason Lindsey is a science outreach educator with Hooked on Science. Check out his website athookedonscience.org.