Light What is light and how does it travel? Vocabulary: Read, listen and repeat: - презентация

1 Light

2 What is light and how does it travel?

3 Vocabulary: Read, listen and repeat:

4 shadow

5 reflection

6 transparent

7 absorb

8 translucent

9 opaque

10 What is light? Light is a form of energy. It is made of waves that move up and down.

11 You can see some light waves. We call these waves visible light. You can see all the colors of the rainbow.

12 You cannot see the other kinds of light waves. They help us in other ways. Doctors use X-rays to check your bones. X-ray waves help us see inside things.

13 How Light Moves Forms of Light Energy Radio waves help us send signals. Microwaves can cook food. Infrared waves are felt as heat.

14 Ultraviolet waves can give you a tan or sunburn.

15 Gamma waves have high amounts of energy.

16 How does light travel? All light moves in a straight path. The light from a lamp moves outward in a straight path.

17 Microwaves in an oven move in straight lines.

18 The light from the Sun moves through space to Earth in a straight path.

19 Light can hit objects. It may bounce off them like a ball. Then it moves in a new direction.

20 The bouncing of light waves off of an object is called reflection.

21 Smooth, shiny surfaces reflect a lot of light. A mirror is an example.

22 A smooth surface makes light bounce back in one direction. The reflection shows us a clear image. A still lake is an example. The water acts like a mirror. We see a clear reflected image.

23 A rough surface makes light bounce off in many directions. It does not reflect a clear image. What you see may look blurry or foggy.

24 How are shadows formed?

25 An opaque object does not let light energy pass through it. It reflects some light energy as well.

26 A shadow forms when some light energy is blocked. The dark space shows where light has been blocked.

27 This umbrella blocks light and casts a shadow.

28 All opaque objects block light. They cast shadows. These shadows form away from the source of light. You cannot see things behind an opaque object.

29 What are transparent and translucent materials? Some objects let light energy pass through them. This lets us see things on the other side.

30 Transparent objects allow most light energy to pass through. Clear glass and clean water are examples. You can see things on the other side.

31 Translucent objects let some light through. Some light is absorbed and some is reflected. This makes it harder to see things on the other side.

32 This window has both transparent and translucent glass.