Final answer:
The property of light that is utilized in the garage door opening mechanism which stops the door when a cat runs underneath is the photoelectric effect, where light hitting a receiver is interrupted, triggering the door to stop. Additionally, light's small wavelength means it doesn't bend around corners, ensuring any interruption is detected.
Step-by-step explanation:
The property of light that applies to this situation is the photoelectric effect, which is observed when light incoming on a surface causes the emission of electrons. In the case of a garage door opening device, a light source emits a beam pointed at a receiver.
This receiver likely uses the photoelectric effect; when the cat interrupts the beam, the change in light detected at the receiver triggers a response that stops the door from moving. This functionality is critical for the prevention of injury or damage by the garage door.
Another aspect that could be considered is non-bending of light. When light passes through an opening, it doesn't bend around corners due to its very small wavelength in relation to the size of most everyday objects, such as a garage door. Thus, when the cat crosses the path, it will block the light from reaching the receiver, triggering the mechanism to stop the door.