Does turning on a light bulb use more power?

I've heard that turning a light bulb on/off uses 20 minutes worth of power up? Is this true?

i.e. If I leave the room for 15 minutes is it actually better to leave the light bulb on?

No it does not use up 20 minutes of power. Turning the light on does not require any more additional power than it does normally take to run it because the light bulb does not have a ballast that must be charged prior to turning it on. Flouscent lights do have ballasts and should not be turned on and off every 15 minutes however the standard light bulb does not. The electrical lines in your walls such as your wall sockets have electricity constantly, because of resistance, electricity is constantly expended in those lines to keep them charged, so if you never use an appliance, light. or anything you will still be billed for a small amount of electricity because you loose some to keep all the lines charged with electricity....

I hope that shed some light for you. Yes Yes!!!!!!!!!!!!!!!!!!!!! But turn the light off when you leave the room. No, it doesn't change the rate of power consumption. But it does cause the bulb to wear out faster. a tube light or discharge lamp such as street lighting do use more power to start up but not that much and normal bulbs should be switched off when not in use even the government adverts being shown now advise switching off but the best we can do is not leave appliances such as t.v's or computers on standby this wastes alot of electricity, and virtualrealitys ,the notion you pay to charge up the wires is rubbish electricity has to have a complete circuit to flow either through an appliance or to an earth through a resistance so if you are using electricity with everything switched off you have a wiring problem Yes, this is the main reason why bulbs burn out. The shock and overload of the action of the electrons barging through the filament increases attrition with every use.