Photogate Timers
Photogate Timers - Related Videos
09:46
Conservation of Momentum
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2023
Source: Nicholas Timmons, Asantha Cooray, PhD, Department of Physics & Astronomy, School of Physical Sciences, University of California, Irvine, CA The goal of this experiment is to test the concept of the conservation of momentum. By setting up a surface with very little friction, collisions between moving objects can be studied, including their initial and final momenta. The conservation of momentum is one of the most important laws in physics. When something is conserved in physics, the...
08:00
Force and Acceleration
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2023
Source: Nicholas Timmons, Asantha Cooray, PhD, Department of Physics & Astronomy, School of Physical Sciences, University of California, Irvine, CA The goal of this experiment is to understand the components of force and their relation to motion through the use of Newton's second law by measuring the acceleration of a glider being acted upon by a force. Nearly every aspect of motion in everyday life can be described using Isaac Newton's three laws of motion. They describe how objects in...
06:58
Animal Behavior - Student Protocol
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2019
Making Choice Chambers ExpandBefore beginning the experiments, use one of the Sharpies from the lab table to trace a line around the circumference of the bottom of both bottles. One line should be 1 cm from the base of the bottle and the other should be 1.5 cm from the base of the bottle. Use a razor blade to make a small cut in each bottle at the mark. Then, insert the scissors and carefully cut along the line until the bottoms of the bottles are removed completely. Fit one bottle bottom into...
05:32
Optimal Foraging - Student Protocol
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2019
Simulating Foraging with Artificial Habitats and Prey ExpandNOTE: The foragers will hunt for prey represented by pinto beans in four buckets of rice with varying prey densities. Without knowing what these densities are, foragers must obtain as many prey items as possible in as little time as possible. HYPOTHESES: In this experiment, the experimental hypothesis could be that foragers will catch the most prey in the higher prey density bucket and also spend the most time foraging there. The...
02:42
Analyzing Synaptic Vesicle Recycling and Fluorescent Dye Uptake in Drosophila Larvae
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2025
This video demonstrates a protocol to study synaptic vesicle recycling at neuromuscular junctions in channelrhodopsin-expressing Drosophila larvae using a fluorescent dye. Blue light activates the channelrhodopsins, causing calcium influx and synaptic vesicle exocytosis. The dye integrates into the neuronal membranes and is internalized during endocytosis, resulting in enhanced fluorescence. Further blue light stimulation induces exocytosis and dye release, which is shown by reduced...
FAQs
The timer can operate in two useful timing modes: it can record how long a single object interrupts a beam, or measure the interval between events at successive gates. The first measurement becomes useful when the object's length is known, while the second uses known gate spacing. Selecting the mode determines whether the data describe passage duration or travel between positions.
Velocity and acceleration are obtained by pairing measured times with known distances. A known object length lets interruption time represent the time associated with that length, whereas known spacing between gates supplies the distance traveled between recorded events. Comparing resulting velocities across positions provides a basis for evaluating acceleration in kinematics experiments, rather than relying on a single timing measurement.
Photogate timers reduce the reaction-time errors that occur when a person starts or stops a measurement by hand. The detector responds when an opaque object interrupts the light beam, allowing the instrument to record short passage durations or intervals consistently. This advantage is especially important when experiments require quantitative comparisons between motion measurements and physical laws.
A basic setup requires a light emitter and detector arranged as a gate, an opaque moving object, and either a known object length or a known spacing between successive gates. The timer records the relevant interruption or interval, and the measured time is then paired with the known distance. This arrangement supports calculations of velocity and, when positions are compared, acceleration.
Photogate timers support investigations of kinematics, free fall, collisions, rolling motion, and oscillations. In each case, the instrument supplies timed motion data that can be related to distance, gate spacing, or object dimensions. This range makes the technique useful for examining both translational and repeated motion, while reducing dependence on manual timing during experiments.
The measurements provide numerical times that can be converted into velocity and acceleration using known lengths or spacings. Researchers can compare those calculated quantities with the predictions of a physical law or an experimental model. Agreement or disagreement between the measured motion and the prediction helps assess how well the model describes phenomena such as free fall, collisions, or oscillations.