SILVER

#### Tired of biting into raw fruit?

I will measure how a photoresistor's resistance changes when I illuminate different color surfaces with a red LED, and then use that information to build a circuit that can differentiate between red and green surfaces

## If the colour of the object matches the colour of the light shined at it, then the object will reflect the light into the photoresistor, reducing resistance which triggers the second LED light to turn on thus differentiating the coloured object.

### Observations

Table 1: How much light each coloured contruction paper reflected back into the photoresistor when red light is passed through it {resistance~Ω}

Resistance

 Paper colour Trial 1 Trial 2 Trial 3 Average Red 0.725Ω 0.717Ω 0.710Ω 0.717Ω Orange 0.689Ω 0.691Ω 0.676Ω 0.685Ω Yellow 0.678Ω 0.680Ω 0.682Ω 0.680Ω Green 1.050Ω 1.113Ω 0.952Ω 1.038Ω Blue 0.901Ω 0.931Ω 0.925Ω 0.919Ω Purple 1.196Ω 1.190Ω 1.199Ω 1.195Ω Pink 1.441Ω 1.474Ω 1.573Ω 1.496Ω Black 1.628Ω 1.633Ω 1.645Ω 1.635Ω White 0.775Ω 0.857Ω 0.863Ω 0.832Ω

Table 2: Whether or not the second LED light turned on

 Colour of fruit Trial 1 Trial 2 Trial 3 Green ✘ ✘ ✘ Red ✓ ✓ ✓

## -construction paper is usually rough so the light could have reflected off to different directions rather than directly into the photoresistor. (Light reflects from a smooth surface at the same angle as it hits the surface. For a rough surface, reflected light rays scatter in all directions.)

### Acknowledgement

SCIENCE TEACHER

She gave me a good understanding about light and the concepts of it

"Light reflects off certain surfaces differently"

"the angle of incidence and  angle of reflection are not always the same for every surface"

"rough surfaces scatter light in all directions for example, scrumpled up tinfoil "

MOM

she gave me the idea of the project

"I could'nt tell which apples were ripe"

"mabye there are electronic devices farmers use to identify ripened fruits

"If its hard for us to pick out ripened fruits, imagine how hard it would be for farmers to pick them"