Breaking Lights

Flashlights fascinate my kids. Lately they have discovered the many varieties of flashlights we have around the house and they can spend hours of nighttime fun with them. One night we were all on Briana’s bed with the lights off, sending sparks of light across the room by flashing the lights on and off. I shone mine right into her mirror and showed the kids how the light was bent onto the ceiling. They were so excited. We did this every night for a week until I decided to show them some more cool light tricks.

Today we will bend light, absorb light, reflect light, and shine light.

Bending light

I start by asking the kids if they think they can bend light? “Yes. If I put my hand on it.” Says Briana unimpressed.

“Well, do you know what it is called when you bend light? It is called refraction. You know what else, water refracts light very well.” I say trying to excite her. “That means that when the light comes into a transparent surface (that you can see through) like water, the light that you can see changes direction.” I get out a glass vase, filled with water, and a flashlight to show them.

Flashlights and water?! Recipe for kiddie fun. Both girls come over to the table to see what I’m up to today. When I turn off the kitchen lights they nearly explode with anticipation.

We watch how the light comes straight into the vase but shows up on the table below. We also look down from the top of the vase and see how the light stream seems to break up and move through the water. 

We note that refraction can split the light into a rainbow…kind-of. I tell them that and we try to make it happen, but it doesn’t fully work today. We get some reds and yellows, but my kids are picky. “It only makes part of a rainbow because we need all of these colors- red, orange, yellow, green, blue, indigo, and violet or it’s not a rainbow.” They both agree that we can only make part of a rainbow with light refraction. OK, you’re right.

We experiment with different sizes of flashlights.

Regardless of amount of light that goes in, it refracts every time!

Then I drop a pencil in the vase and we look at the broken pencil, but when I pull it out, it’s whole. I explain that the pencil didn’t break. The light was bent and made the pencil look bent.

I tell the kids that refraction happens with all transparent surfaces. What else can we see through that might refract light? Glass! Windows! Bags for apples! (Ziploc bags.) They excitedly look around.

We experiment, shining our lights through windows, and Ziploc bags, and cellophane. Sure enough, transparent surfaces keep refracting that light.

Then the girls note something very interesting. Briana’s smaller flashlight makes a v when left on the table. Abby’s makes a rectangle. We stop and talk about how certain things absorb the light instead of refract it. The plastic corners of the flashlight absorb some of the light, stopping it from hitting the table. Briana’s flashlight has large, protruding sides whereas Abby’s does not, so there is nothing to absorb the sides of Abby’s light’s rays.

Rather than go to reflection next, we talk more about absorption of light.

Absorbing light

Sometimes, what you shine the light on actually absorbs or blocks the light. That is what makes shadows. What do we think could absorb the light and make a shadow? "We do!" They shout.

We experiment with shadow puppets. That’s Abigail’s creepy crawly spider

Dolls do too. Poor crushed baby! But sure enough, she absorbs the light and casts a shadow on the floor.

Cups do. “Everything that isn’t clear does, I think.” Briana understands. We experiment.

Her theory is almost true. If it is clear, it refracts light. If it is opaque it usually absorbs light. But if it is reflective, it reflects lights. (*See ending notes for diffraction.)

Reflecting light

Sometime the light is moved to another spot. We call that reflected. Like with the mirror.

“No that’s refrACTion.” Briana corrects.

I explain. The difference is, with refraction, the light bends but you can still see it in a line. In reflection the light jumps to a new spot. They stare at me, not quite getting it. It try again. Refraction is a change of direction. Reflection is light bouncing off a surface. They still look confused. I change tactics and say refraction is like if you’re running in a straight line in gymnastics and decide not to vault so you turn to avoid running into the vault. Reflection is like if you’re running in gymnastics towards the vault and you do want to vault so you bounce off the springboard. They are similar because in both cases you end up on the other side of the vault but how you get there is different. That makes total sense and they are with me on reflection now.

We experiment.

Shining light

Then we spend some good old fashioned time just shining light around the darkened bathroom.

*In case you are curious or want to expand this, the one thing we didn’t talk about is diffraction of light. I thought it would be too much new vocabulary for my kiddies today and I didn’t want to totally confuse them. In any case, diffraction is when the light changes direction because the plane that it bounces off of is not flat. A good experiment for kids to demonstrate diffraction would be to shine lights on a crumbled up piece of aluminum foil. The light should split out in multiple directions and that’s diffraction.

I hope this has been illuminating. J

<3 Pedigreed Housewife