I drew a line with torch light putting front part of a ballpoint pen onto torch light head so that the light coming out from the point of a pen was considered as a ray of a light. By covering outer part of the torch with a black T-shirt would let the light to come out only from the small hole of a pen. I repeated the same process 29 times. Each time the torch would blink, the camera would record the blinking of the light. The path so travelled by the light of a torch was considered as a straight line.