Data Sheet
VMA501
V. 01 – 29/03/2017 13 ©Velleman nv
7.6 The Photosensitive Resistor
A photoresistor is a resistor whose resistance varies according to different light strengths. It is based on the
photoelectric effect of a semiconductor. If the incident light is intense, the resistance reduces; if the incident
light is weak, the resistant increases. A photovaristor is commonly applied in the measurement of light, light
control and photovoltaic conversion.
Let’s start with a relative simple experiment. The photovaristor is an element that changes its resistance as
light strength changes. Refer to the PWM experiment, replacing the potentiometer with a photovaristor. When
there is a change in light strength, there will be a corresponding change on the LED.
Required Hardware
1 x photoresistor
1 x red M5 LED
1 x 10KΩ resistor
1 x 220 Ω resistor
1 x breadboard
jumper wires as needed
Connection