S2.6.2 For the adult
Light goes in straight lines
Can light go round a corner?
What this chapter teaches
In air, light travels in straight lines, which is why a shadow has a sharp edge. Light seems to go round a corner only when it bounces off things.
Three questions to ask
There is no one right wording. Listen for the idea.
- How would you test whether light can go round a corner?
- Why do you think the edge of a shadow is sharp?
- What would you see if you moved one of the three cards, and why?
After the chapter, the learner can
- Show that light goes in a straight line
- Use three cards or a tube to test it
- Explain why a shadow has a sharp edge
What they copy into their notebook
In air, light goes in straight lines. A ray is one line of light, drawn with an arrow. A card blocks rays and makes a shadow. The shadow has a sharp edge.