These Light Dependent Resistors (LDR) have are great for 5v applications such as Arduinos, Raspberry Pis and ESPs. They have a resistance range of 0 – 2M Ohms (Ω).
Use them in projects to detect when it has turned dark or use an array of the to detect where the sun is located in the sky.
In light, the resistors have a resistance of between 0 – 20k Ohms (Ω) compared to over 2M Ohms (Ω) in the dark.
Note: Price is per individual resistor. Image is for illustrative purposes only