The resistance of a conductor is the ratio of the voltage
between its ends to the current through it.
If the voltage between the ends of a light bulb's filament
increases but the filament's resistance remains constant,
then the current through it increases by the same factor
as the voltage increase. The effect is to cause the light
to emit more light and heat ... both increase proportional
to the square of the voltage ... and possibly to "burn out".
