Comparing the effectiveness of a light sensor and a touch sensor
The hypothesis that the light sensor will be more effective even with a faster conveyor belt is proven to be correct. The light sensor did not require physical contact with the sensor whereas the touch sensor required physical contact for detection. This resulted in greater friction between the boxes and the sensor and as the speed of the conveyor increased, causing the boxes end up being displaced.
Sensors can be found everywhere around us. When we turn on the air conditioner, the thermostat detects and regulates the temperature in the room. Street lights also have a light sensor where the lights automatically switch on at night and automatically switch off in the mornings. There are also many sensors within a car which help to detect engine temperature, unclosed doors and fuel levels.
Try to repeat the experiment by using other sensors like a proximity sensor.
The experiment can also be done by increasing or reducing the space between the boxes.
Sensor - http://en.wikipedia.org/wiki/Sensor
About different types of sensor - http://www.ehow.com/about_4621381_different-types-sensors.html
Electronic counters - http://www.robotroom.com/Counter.html