Which is more costly?

you don't have to switch if off if you are leaving for a few minutes the old tungsten bulbs will actually blow faster if you do,the usage from a light is nominal anyway. a 100 w bulb will use one KWH of electricity in ten hours so you aren't saving much by turning them off and on that often

Who told you turning lights on and off was costly ?

Clearly a switch is just the mechanism to power or not power something and it costs you nothing to flick a switch. What costs you is the light when it's on, turn it off if your leaving the room and save yourself money on the electric bill.

Probably not. No more energy is being expended when the circuit is completed or being broken. Now if there is you have to weight this against the draw of the devices that stay on such as the lights. Now it is more cost effective to leave the a/c alone when you leave for the day.

Turning the light off and on will only decrease the life of the bulb. It won't effect your light bill.

Nonsense. Turn the light off to save power.

switch them on and off as u leave the room. they tested it on myth buster. for florescent tubes however, leave them on if ur gonna be out of the room for less than 23 seconds. other than that, turn ur lights off when u leave a room

When I was a kid I was told it cost 10 cents every time you turn on a light but who knows

If it is an energy savaer light leave it on, it will burn out quicker. Otherwise turn it off,

Turn it off. You are thinking of the TV rule.

For a few minutes might not make a difference, but