EVERYDAY SCIENCE - LIGHT

Question 2

Ace was studying about cacti in a desert when he got lost. He knew that the nearest town lies to the north but he did not know which direction was north.

At 5 p.m. in the afternoon, he came across a large cactus which was casting a shadow in the sand. He took a photo of the cactus as shown.

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Answer 1

Fill in the blanks with the keywords provided below.
[reflected] • [shadow] • [east] • [south] • [west] • [blocks all light] • [straight lines] • [eyes]

a) Explain how Ace was able to see the shadow of the cactus.

Answer:

Light from the Sun travelled in to the cactus and the sand. The cactus is opaque and from passing through to the sand, casting a shadow. Light that was not blocked by the cactus travelled to the sand surrounding the shadow. The light was by the sand into Ace’s .


b) Based on the photo, which direction should Ace travel in order to reach the town? Explain your answer.

Answer:

Ace should walk backwards, away from the cactus plant. In the afternoon, the Sun is in the . The of the cactus points to the , away from the Sun. Therefore, Ace was facing when he took the photo, and north will be behind him.




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“Humans have used sundials to tell the time since 3500 years ago. The world’s largest stone sundial is the Jantar Mantar, found in Jaipur, India and was constructed in the 18th century!”