1. Can life on Earth exist without light from the sun?
2. Light makes up only a small fraction of energy that comes to us from the sun. Right or Wrong?
3. Light travels through space at _______________ kilometers per second.
4. How long does it take for light to reach the Earth from the sun?
5. Is sun the only source of light?
6. What is meant by ‘luminous’?
7. Give 5 examples of sources of light we use in our daily life that are luminous.
8. What does ‘incandescent’ mean?
9. Explain the term ‘bioluminescent’ and give lots of examples.
10. The sun and all other stars are __________________. (bioluminescent/incandescent)
11. How are we able to see non-luminous objects?
12. Moon is not a luminous object. Then how do we see it?
13. How do deep-sea fish like the anglerfish, viperfish and the black dragon fish attract their prey?
14. Glow-in-the-dark stickers are made with a chemical called _____________.
15. Explain the process of phosphorescence.
16. Why are we not able to see the beam of light from the headlights of a car, between the source and any surface that it strikes, on clear nights, but are able to see it on a foggy night?
17. Does light travel at the same speed in space and in the Earth’s atmosphere?
18. Why is space black despite billions of stars?
19. Does phosphorescence occur in the natural world?
20. Give some instances of phosphorescence in our daily life.
21. How long would it take for light from the sun to reach Uranus?
22. Look at the streetlights at night and describe what you observe about the beam of light.
23. Besides light, what are the other forms of energy that we receive from the sun?