By electric, I'm assuming you're referring to the digital thermometers that are battery operated. The cheap ones that you can buy at the drugstore are probably less accurate than a mercury thermometer. However, the more expensive and better made ones that the doctor's office uses are more accurate. Mercury thermometers are the most ideal because they maintain the temperature reading after they are removed from the person's mouth, rectum, etc. They have to be shaken to go back to a baseline temp. For taking room temperature, an alcohol thermometer, such as the Galileo thermometer, is less influenced by drafts and mild fluctuations in room temperature. As to the first question, I cannot say with complete accuracy, but my best guess is that the thermometer would be just as accurate if all aspects of it are the same as the day you bought it--such as the battery having the same charge, etc. On another note--if I'm not mistaken, mercury thermometers will not be sold anymore beginning this year. I believe that red alcohol thermometers will replace them due to the dangers of spilled mercury.

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