Final answer:
Plugging a 220V device into a 120V outlet leads to insufficient voltage for the device, causing it to perform poorly, not operate, or be damaged. Too high a voltage can cause overheating and fire hazards.
Step-by-step explanation:
When you plug in a 220V device into a 120V outlet, the device will receive less voltage than it was designed to handle. This can result in the device running less efficiently, or potentially not working at all. In some cases, it could cause internal damage to the device because it's not receiving the proper operating voltage. For example, a 120W, 220V lamp would not function correctly at only 120V, and an electrical device intended for 240V when connected to a lower voltage, might operate at a lower power level or may fail to start, but if it's the other way around (connecting a 120V device to 240V), the increased voltage can lead to overheating, damage, or even a fire hazard.