Light and dark 1. Sources of light 2. Seeing objects 1. Sources of light A source of light makes its own light. The sun and other stars, fires, torches and lamps all make their own light and so are examples of sources of light. Remember! You must never look directly at the sun. It is so bright that it can damage your eyes very quickly. Some animals, such as fireflies and glow-worms, are light sources. They make their own light to attract mates. A mirror is not a source of light. It doesn t make its own light, it just reflects light. The moon is not a source of light. It reflects light from the sun. You would not be able to see a reflector of light, such as a mirror, in a completely dark room. 1
2. Seeing objects We see a light source when light from the source enters our eyes. When light from a light source hits an object, it is reflected (bounces off) and enters our eyes. This is how we see the object. 2
Test Questions 1. Can you see in the dark? a) Yes b) No c) Only if I eat a lot of carrots 2. We see a source of light because it a) reflects light b) blocks light c) makes its own light 3. Which of the following is NOT a source of light? a) Lightning b) A switched-on television c) A window 4. Which light source would you use to read in bed at night? a) The sun b) A lamp c) A burning fire 3
5. Which light source is dangerous to look at directly? a) Fairy lights b) A lamp c) The sun 6. How do we see a flower in the garden? a) Light from the sun bounces off the flower and enters our eyes b) The flower produces a light that enters our eyes c) Our eyes produce a light that hits the flower 7. A car drives at night with its headlamps on. The driver sees a pair of bright cat's eyes on the side of the road. How can the cat's eyes be seen? a) The cat's eyes are sources of light b) The cat's eyes reflect light from the headlamps into the driver's eyes c) Light from the driver's eyes reaches the cat's eyes 8. Does a reflective strip shine brightly in a dark cupboard? a) Yes b) No c) Reflective strips never shine 4
9. Which one of these things gives out light? a) The moon b) A mirror c) A burning fire 10. Shiny things such as mirrors and tinsel appear shiny because they... a) reflect light b) absorb light c) give out light 5
ANSWERS 1 Can you see in the dark? Your answer - No. That's right! No person can see when it's completely dark. You need a light source to see things. 2 We see a source of light because it Your answer - makes its own light. That's right. We see sources of light such as fires, torches and lamps because they make their own light. 3 Which of the following is NOT a source of light? Your answer - A window. That's right, a window lets light pass through it but does not make its own light and so isn't a source of light. 4 Which light source would you use to read in bed at night? Your answer - A lamp. A lamp would be a good choice to help you read at night. 5 Which light source is dangerous to look at directly? Your answer - The sun. The sun is so bright that it can hurt your eyes and affect your eyesight. 6 How do we see a flower in the garden? Your answer - Light from the sun bounces off the flower and enters our eyes. Yes, we see an object when light from a light source hits the object, is reflected (bounces off) and enters our eyes. 6
7 A car drives at night with its headlamps on. The driver sees a pair of bright cat's eyes on the side of the road. How can the cat's eyes be seen? Your answer - The cat's eyes reflect light from the headlamps into the driver's eyes. You got it! Light from the car headlamps is reflected by the cat's eyes into the driver's eyes. 8 Does a reflective strip shine brightly in a dark cupboard? Your answer - No. It doesn't shine because there isn't any light to bounce off it. 9 Which one of these things gives out light? Your answer - A burning fire. A burning fire gives out a lot of light. 10 Shiny things such as mirrors and tinsel appear shiny because they... Your answer - reflect light. Shiny things reflect the light that hits them. 7