Why is the current in an incandescent bulb greater immediatley after it is turned on than it is a few moments later?
2007-12-03 07:24:39 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Physics
the difference in temperature is the clue
and tungsten has a fairly high temperature coefficient of resistivity (3 times as high as copper)
from cold to white hot is a very big change in resistance
I should look it up ....but it's in the order of a 10 times as much as the instantaneous cold current but limited by inductance
and instantaneous value of the voltage at turn on.
time to fall to "safe" value .. 10 to 20 mS
bulbs have been used as the non-linear element in wein-bridge oscillators
2007-12-03 07:53:28 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Its resistance when cold (at turn on) is less than the resistance when hot.
2007-12-03 15:27:05 · answer #2 · answered by za 7 · 0⤊ 0⤋
he's right
2007-12-03 15:33:41 · answer #3 · answered by dannymoeller 1 · 0⤊ 0⤋