The Path of Light

Purpose: To discover how light travels

Materials

• 3 index cards
• small piece of modeling clay or sticky tack
• flashlight
• hole puncher
• ruler
• science journal

Procedure

1. For each index card, use a ruler to draw lines connecting opposite corners of the card.
2. At the intersection of the two lines, use a hole puncher to punch a hole in the center of the index cards.
3. For each card, use a small piece of modeling clay and place the card into the clay to create a "stand" for the card. Place the cards so that they stand vertically and at an equal distance from each other. See Diagram.
4. Place the flashlight at one end of the row of index cards and turn off the light in the room.
5. Arrange the index cards so that light can be seen through all the holes.
6. Observe and record your observations.

Conclusion

1. How can light be seen through all the index cards?
2. What does the experiment prove about the path light travels?
3. What would happen if the holes were smaller?

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Answer Key

1. How can light be seen through all the index cards?

The holes are in alignment and the light travels in a straight line.

2. What does the experiment prove about the path light travels?

Light travels in a straight line.

3. What would happen if the holes were smaller?

The light would continue to travel in a straight line but in a more restricted path.