Lamps

Moving from STL to London in 3 weeks, and trying to determine if we can bring a few lamps. They have polarized plugs but no other voltage info on cords. Sticker on lightbulb socket says 120v; 60 hz, but not sure if that applies to cord or bulb.

Do we have to re-wire or just find plug adapter?

Thanks...Jim

I use a plug adapter and have for years. Don't bring the bulbs - they will blow; use 220-240 rated bulbs. Edison screw ends are easy to find here now; years ago, that was a challenge.

Some folk will tell you that re-wiring is needed, and perhaps it is, but I've never had issues. I do use low wattage LED or LCD bulbs in all my laps however.

Provided the wires aren't old and brittle, you shouldn't have  a problem. I think I remember that higher voltage actually creates less wire heat.

I would probably be more concerned with the condition of the wire....lamp wire is often crappy to begin with. 

Are the lamps old?

Well, now for a wee physics lesson:

Power is the amount of energy transferred every second, so the amount of heating through the wires is determined by how much energy is being transferred and the resistance of the wires.

P = I(squared) *R, which means that currents have a huge effect on heating. P = V (squared) / R which also means that Power is proportional to the voltage squared. Lower currents (and higher voltages) tend to have a slightly less heating effect than higher currents with lower voltages. (although in this case, there is the added complication of lower resistances of lightlbulbs with lower currents because bulbs are non-ohmic).

Anyway, back to lamps: Use UK bulbs and pay close attention to the power rating and use something similar; you should be fine. My real concern is the lack of safety features in the two-prong plug of a US lamp. All plugs in the UK are fused and have an earth prong. I would get the lamps replugged.

because bulbs are non-ohmic

Well I won't get any work done till I find out what that means.

Well I won't get any work done till I find out what that means.

Resistance of the resistor changes. Some resistors change resistance as current changes, others when temp or lighting conditions change etc...

Non-ohmic means the resistor doesn't obey Ohm's Law; ie current and voltage don't change proportionally.

Welcome to A level physics.

I've never really trusted electricity. It seems sinister.

I remember mowing the yard as a child and I got the urge to touch the end of the spark plug on the lawnmower. It couldn't do much could it? It's just a little spark plug, not a heavy duty generator....just a little magneto.....but wow