Shadows
Explore the difference between opaque, transparent and translucent materials and create shadows.
What You Need
- 1 paper cardstock circle
- 1 piece of clear acetate
- 1 popsicle stick
- Tape or glue
- Flashlight
Guide:
Safety Notes
Ensure you are familiar with Let's Talk Science's precautions with respect to safe virtual outreach to youth.
What To Do
- Take a flashlight and place it on a table facing a wall. Turn on the flashlight (Optional: turn off the lights in the room).
- Take the cardstock circle cut out and hold it up halfway between the flashlight and the wall. What do you observe?
- Take the piece of acetate (see-through or transparent material) and hold it between the flashlight and the wall.
- What do you observe?
- Are there any differences in the shadow with the cardstock and the acetate, besides the shape?
- Which material makes the darkest shadow?
- Why do you think one makes a darker shadow than the other?
- Tape the popsicle stick to the back of the cardstock so you have a handle. This time, move the circle closer to the flashlight, then closer to the wall.
- What do you notice about the size of the shadow?
- Is the shadow bigger when you are closer to the flashlight or closer to the wall?
Discovery
To make a shadow, you need an object that can block out light. In science, we call these objects opaque (like the cardstock circle). Materials that light can travel through (like the acetate) are called transparent. Transparent materials do not make a shadow or make a very light shadow. Some materials, like a plastic grocery bag or your shirt, allow some light to travel through and we say the objects are translucent.
When you move an opaque object closer to the light source (the flashlight or the sun), it will block out more light and make a bigger shadow. If you move the opaque object away from the light (towards the wall), it will be further away from the light and make a smaller shadow.
If you do not have a flashlight, you can do this activity outside on a sunny day. Instead of a flashlight put the circle between the sun and a wall or the pavement/ground to see the shadow.
Guide:
What's Happening?
To make a shadow, you need an object that can block out light. In science, we call these objects opaque (like the cardstock circle). Materials that light can travel through (like the acetate) are called transparent. Transparent materials do not make a shadow or make a very light shadow. Some materials, like a plastic grocery bag or your shirt, allow some light to travel through and we say the objects are translucent.
When you move an opaque object closer to the light source (the flashlight or the sun), it will block out more light and make a bigger shadow. If you move the opaque object away from the light (towards the wall), it will be further away from the light and make a smaller shadow.
Investigate Further
If you do not have a flashlight, you can do this activity outside on a sunny day. Instead of a flashlight put the circle between the sun and a wall or the pavement/ground to see the shadow.