Tag Archives: photoresistor

What’s a Photometer? All About Our Light Sensitivity DIY Kit!

“I love plants and have some in my bedroom window and now I can measure how much light they’re getting!”

—5th grade student, SAR Academy 

In our last blog post we talked all about what a breadboard is and how it can help us tinker and explore. In order to learn more about light and electronics, we’re also going to use a breadboard to experiment and make our own DIY photometer. 

A photometer is a tool that measures the strength of light. It converts light into electricity using a photoresistor (fishersci.com).

Once we make that…well then the options are endless what we can do with it! One way, pictured above, is to measure how much light our plants are receiving to make sure they’re staying healthy.  

We already know all about how beneficial experimentation and curiosity is to deeper learning, and with this DIY Kit, we dive deeper into circuitry. In order to make our own photometer, we will need the breadboard, LEDs, batteries, jumper wires, and a photoresistor.

What’s a photoresistor?

You’re walking down the street at dusk—the light is hazy and golden. As you round the corner, the sun begins to set…and as it gets darker…the street lights POP on. This is because there’s a tiny piece of electronic hardware in the lamppost called a photoresistor. It doesn’t have a positive or negative terminal, so electricity can flow through in either direction.

A photoresistor is a type of resistor. Resistors work similarly to a kink in a garden hose slowing or stopping the water. When we add a resistor to a circuit before an LED, we can dim the LEDs brightness. You might use a resistor to dim the lights in your home.

What makes photoresistors special is their ability to sense light. If it senses a lot of light, it reduces resistance and lets electricity flow. If it doesn’t sense light, it creates a large amount of resistance and prevents electricity from flowing.

How do we make the photometer?

First, we insert the photoresistor in the breadboard. Then, we insert the jumper wires. Now we can follow our created circuit! The DIY kit includes all the fun instructions to create your own tool. 

How is the photoresistor relevant to our daily lives?

Every day we interact with electronic devices in many ways—buttons, switches, remote controllers, voice commands, touch screens, night lights, etc. Photoresistors allow us to interact with electronics in a very cool way. 

The Light Sensitivity DIY kit is designed to demonstrate the way we can interact with electronics using light, which helps with visual learning. We can even see the level of light that our plants are receiving by the brightness of the LED, which makes this DIY kit extremely interactive and useful even after assembly. 

Therefore, students learn while they make the photometer and then they can observe their surroundings with their newly created tool!