Preserving the lifetime of a bulb ??? My father claims that is is better do leave a light bulb on rather than switch it on or off when used often because he says, "Electric charges are very fast and damages the filament inside with each flick of the switch closing the circuit, even more damage than leaving the lightbulb on constantly, within the same period of time", effectively increasing the lifetime if the bulb, I really want to know, is this true ? While on the same topic.. Is it true the greater the current in a conductor the greater the velocity of the charges ? What is the most effective way of preserving the lifetime of a bulb ?