Free Fall Apparatus With Wireless Photogate

Item Code: SK196

Principle and Working:

Free fall instrument is necessary for the quantitative analysis of free falling objects and measurement of value of ‘g’, acceleration due to gravity.

... In the present setup, the value of “g” may be obtained with the help of Master - Slave Photogates and a falling ball dropped by solenoid using the equation,
g = 2(h2 - h1 ) / (t22-t22)
where h2 - h1 is the distance between the Photogates.




  • Unique semi-wireless solution to perform ‘g’ by free fall experiment.
  • Primary and Secondary light gates communicate with laptop or mobile phone on wireless bluetooth link.
  • Primary light gate has inbuilt Digital Timer with 100 microsecond resolution and built-in rechargeable cells.
  • Communication between Primary, Secondary light gates and Solenoid is wired.
  • Graphical display of blocked pulses can be observed on PC software, android app and iOS app.
  • Primary and Secondary light gates can be used with air track and dynamic trolleys, to study linear motion on inclined plane and collision experiments.
  • Solenoid is only powered when ball or dowel is in position, so conserving battery power.
  • Daisy Chaining Facility available for connecting multiple Light gates

  • To determine the value of “g” by dropping metal ball/dowel using solenoid through a pair of light gates
    • Experimental Stand : Height 1300 mm , Heavy ‘A’ shape base, ‘U’ CHannel Stand, 120 cm printed scale
    • Primary Gate : Operating Volatge 9 VDC, Microcontroller Based, Time resolution : 0.1 milli second, Operating Systems : Windows/iOS/Android, Infrared source: Peak at 880 nm, Output is Low and LED off for unblocked gate,Output is High and LED on for blocked gate,Data Transfer to PC/Smart devices : Wireless Bluetooth
    • Secondary gate : Infrared source: Peak at 880 nm, Output is Low and LED off for unblocked gate,Output is High and LED on for blocked gate,
    • Solenoid Driver : Cu Coil, Wire Connetion to Primary Light Gate, LED Indicator for solenoid Activation, Dimension 135 x 100 x 65 mm
    • 1 Free fall stand
    • 1 Primary light gate
    • 1 Secondary light gate
    • 1 Wireless solenoid module
    • 1 Steel ball/dowel
    • 1 Thread roll
    • Free fall.
    • Acceleration due to gravity.
    • Line of sight & IR.
    • light gate.
    • Bluetooth.
    • Solenoid.