Year 7 Energy, Light

There are many components to light and we humans can only observe a very narrow band of it with our naked eyes. We call this very narrow band the “visible light spectrum” for that very reason. You may be familiar with some of the other wavelengths of light listed below like X-rays and FM or AM radio, however, today we’re looking at only visible light and infra-red rays.

Image result for light spectrumhttps://qph.fs.quoracdn.net/main-qimg-45d477f26e512244e9adfb0cf4f08040.webp

You can experience light from many different sources. Spend the next 5min brainstorming in class where you might find sources of visible light energy.


Now infrared light sounds like a new thing, however it’s something that you experience everyday and you would be rather cold without it. We humans can actually feel infrared light as heat. You are constantly emitting thing infrared light from you’re body and into your surroundings. When you put on a jacket, you can trap them in for a bit, but they will eventually come out, depending on the thickness of the jacket and how cold it is outside.

Image result for infrared humanhttp://www.thermohuman.com/new-book-infrared-thermography-detection-injury-sports-medicine/

Visible light can be broken up into 3 main colours that we can see with our eyes. They are Red, Green and Blue (RGB). Right now as you look at this monitor, you are experiencing black text on a “white” background. However, what is really happening is the black is missing light and the “white” is only made of RGB.

If you look at the following colours on your screen with a drop of water on it you may just catch a glimpse of them for yourself

White

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Red

Image result for red screen

Green

Image result for green screen

Blue

Image result for blue screen


Practical

Using your lux meters which are designed to measure the brightness or intensity of light, you will need to try and develop a method to try and see who has the brightest phone in the classroom and who has the darkest. You will need to include the following headings in your book:

Aim – what are we trying to achieve?

Independent variable – what are we going to change?

Dependent variable – what are we going to measure?

Control Variable – things that you will need to have in place to make sure that it is a fair test

Method – how will you make this work? You can use any of the equipment under the benches and your light meter. (If you need a white phone image scroll up)

Results – you might need a table and a graph to show your results

Conclusion – which phone had the brightest display? how much brighter was it?

EXTRA – If you finish this practical early, what happens when you move the sensor closer and further back near the phone? Draw up and extra graph to see if there is a linear relationship with distance and brightness.


Extension

Want to learn how light might be used to diagnose diseases on a computer the size of a 20c coin one day?
Watch the attached video and see why light matters
https://youtu.be/j7heZpuvu4U

Or, solve a crime with Infrared light using this video


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