# Source: https://learn.adafruit.com/adafruit-arduino-lesson-9-sensing-light.md

# Arduino Lesson 9. Sensing Light

## Overview

In this lesson, you will learn how to measure light intensity using an Analog Input. You will build on lesson 8 and use the level of light to control the number of LEDs to be lit.

![](https://cdn-learn.adafruit.com/assets/assets/000/002/273/medium800/learn_arduino_overview.jpg?1396781232)

The photocell is at the bottom of the breadboard, where the pot was in lesson 8.

- [Next Page](https://learn.adafruit.com/adafruit-arduino-lesson-9-sensing-light/parts.md)

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## Related Guides

- [Adafruit Arduino Selection Guide](https://learn.adafruit.com/adafruit-arduino-selection-guide.md)
- [IR Sensor](https://learn.adafruit.com/ir-sensor.md)
- [How to Choose a Microcontroller](https://learn.adafruit.com/how-to-choose-a-microcontroller.md)
- [Adafruit 1.14" 240x135 Color TFT Breakout LCD Display](https://learn.adafruit.com/adafruit-1-14-240x135-color-tft-breakout.md)
- [Adafruit Ultimate GPS](https://learn.adafruit.com/adafruit-ultimate-gps.md)
- [Reverse Geocache Box](https://learn.adafruit.com/reverse-geocache-engagement-box.md)
- [Ladyada's Learn Arduino - Lesson #0](https://learn.adafruit.com/ladyadas-learn-arduino-lesson-number-0.md)
- [How to Find Hidden COM Ports](https://learn.adafruit.com/how-to-find-hidden-com-ports.md)
- [Sending an SMS with Temboo](https://learn.adafruit.com/sending-an-sms-with-temboo.md)
- [Ladyada's Learn Arduino - Lesson #2](https://learn.adafruit.com/ladyadas-learn-arduino-lesson-number-2.md)
- [Arduino Lesson 14. Servo Motors](https://learn.adafruit.com/adafruit-arduino-lesson-14-servo-motors.md)
- [0.96" mini Color OLED](https://learn.adafruit.com/096-mini-color-oled.md)
- [Line Following Zumo Robot Using Simulink](https://learn.adafruit.com/line-following-zumo-robot-programmed-with-simulink.md)
- [Arduino Prototyping Mounting Plate](https://learn.adafruit.com/arduino-prototyping-mounting-plate.md)
- [Babel Fish](https://learn.adafruit.com/babel-fish.md)