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Photocell

Photocell: it facilitates the exact and quick measurement of motions lasting for a short time without recording. This method is based on photo-electronic principles and uses photocells. Two photocells are applied in the line of motions and the time spent between them is measured. A high precision clock is fixed to the photocells which start working when the beam of the first photocell is refracted. It stops when the second beam is also refracted. Beams of light should be set in a way that the same body part/segment would break the beams between the two photocells. By applying this method both the time of motion and its speed can be measured, as the distance between the two photocells are given (Barton, 1983). There are programmes which digitalize signals instantly.