Year 6 Science: Shadows have the same shape as the object
Part of the Year 6 Science light travels in straight lines chapter. Chapter overview · whole chapter on one page
Shadows have the same shape as the object
A shadow forms when an opaque object blocks light. Light travels in straight lines from the torch, past the edges of the object, to the wall.
Light that passes the edges of the object makes the outline of the shadow. Light that is blocked by the middle of the object makes the dark area inside. So the shadow has the same shape as the object, as long as the light and the object are placed the same way.
Key ideas
- A shadow is made when an opaque object blocks light.
- Light travels in straight lines, so it is blocked by the edges of the object.
- The shadow has the same shape as the object that casts it.
- The shadow is on the side of the object away from the light.
Method. Use the idea of straight lines.
- Think about the light. Light travels in straight lines past the edges of the arrow.straight lines
- Write the shape. So the shadow is the same shape as the arrow.arrow
- Write the answer. an arrow
Check. The shadow copies the outline of the object. ✓
Method. Use the straight line idea.
- Think about the light. Light travels in straight lines and is blocked by the edges.blocked by edges
- Write the reason. The reason is straight lines.straight
- Write the answer. straight lines
Check. Light cannot bend round the object. ✓
Method. Think about where the light cannot reach.
- Think about the light. The light comes from the torch, so the card blocks it on the far side.far side
- Write the answer. So the shadow is on the side away from the torch.away from the torch
- Write the answer. the side away from the torch
Check. The side facing the torch is in light. ✓
Watch out
Watch out: a shadow is not the same as the object. It is a dark shape on a surface, and it shows the outline of the object, not its colour or detail.
Exam tip
Exam tip. Use the words straight lines and blocked when you explain a shadow: light travels in straight lines, and is blocked by the object.
Try it (with your teacher, or a grown-up at home). Cut a simple shape from card, such as a star or an arrow. Shine a torch on it, with a grown-up, and hold it close to a wall. Look at the shadow. Is it the same shape? Trace the shadow with a pencil, and compare the shape with the card.
Exercise 7B Shadows have the same shape as the object
Method. Read the definition.
- Read the definition. A shadow is the dark shape made when an opaque object blocks light.shadow
- Write the answer. shadow
Check. Shadows form on the side away from the light. ✓
Method. Use the idea of straight lines.
- Use the idea. Light travels in straight lines, so the outline of the object is copied.outline
- Decide. So the shadow is the same shape, and the answer is yes.yes
- Write the answer. yes
Check. The shadow copies the outline. ✓
Method. Read the idea.
- Read the idea. The shape comes from light travelling in straight lines past the edges.straight lines
- Write the words. So the idea is that light travels in straight lines.light travels in straight lines
- Write the answer. light travels in straight lines
Check. Light is blocked by the edges. ✓
Method. Think about where the light is blocked.
- Think about the light. The object blocks the light on the side away from the light source.blocks
- Write the answer. So the shadow is on the side away from the light.away from the light
- Write the answer. away from the light
Check. The side facing the light is lit. ✓
Method. Use the shadow idea.
- Use the idea. The shadow has the same shape as the object.same shape
- Write the word. So the shadow is a star.star
- Write the answer. star
Check. The outline of the star is copied. ✓
Method. Think about what a shadow is.
- Think about the shadow. A shadow is a dark shape, and it shows the outline of the object, not its colour.outline only
- Decide. So the answer is no.no
- Write the answer. no
Check. Colour is not shown in a shadow. ✓
Method. Use the straight line idea.
- Think about the light. Light travels in straight lines, past the edges of the cube.edges
- Decide. When the light is placed the same way each time, the shadow copies the outline, so yes.yes
- Write the answer. yes
Check. Shape depends on the outline the light passes. ✓
Method. Check what a shadow shows.
- Check the shadow. A shadow is a dark shape that shows the outline.dark shape
- Decide. So Ali is not right.no
- Write the answer. no
Check. Shadows are dark, whatever the colour of the object. ✓
Method. Use the idea that the shadow is the same shape.
- Read the shape. The shadow is a triangle, the same shape as the card.triangle
- Count the corners. A triangle has 3 corners, so the shadow has 3 corners.3
- Write the answer. 3
Check. The corners of the card are copied by the shadow. ✓
Method. Think about the light at the edges.
- Think about the light. Light travels in straight lines past the edges.past the edges
- Think about the shadow. The light that is blocked by the edges makes the outline of the shadow.outline
- Write the answer. Accept any sentence that says light travels in straight lines, so the light that just passes the edges makes the outline of the shadow.
Check. Light past the edges sets the outline. ✓
Method. Think about the hand and the light.
- Think about the hand. The hand blocks the light from the torch.blocks
- Think about the shadow. The straight-line light is blocked, so the dark shape copies the hand.copies
- Write the answer. Accept any sentence that says the hand blocks the light, and light travelling in straight lines makes a dark copy of the hand's outline.
Check. The shadow is a copy of the outline. ✓
Method. Think about the angle.
- Think about the card. A tilted card shows a different outline to the light.different outline
- Think about the shadow. So the shadow on the wall changes shape.changes shape
- Write the answer. Accept any sentence that says a tilted card blocks the light from a different direction, so its outline on the wall changes.
Check. Shadows depend on the position of the object. ✓