Final answer:
Electric cords should not become twisted because it can cause a short circuit, which can lead to excessive current flow and heat generation, potentially causing the cord to melt or ignite materials.
Step-by-step explanation:
You should not allow electric cords to become twisted because it can cause a short circuit. A twisted cord can damage the insulation, allowing wires to come into contact with each other, creating a low-resistance path that can lead to excessive current and heat generation. This can be dangerous as it has the potential to melt the cord or cause a fire.
For example, if the insulation on wires leading to an appliance wears through due to twisting and the wires come into contact, it could lead to an undesired short circuit with high voltage. As described in the physics concept where P = V²/r (power equals voltage squared over resistance), the small resistance in a short circuit means that power dissipation would be very large, potentially leading to melting or ignition of surrounding materials.