in a filament lamp circuit as the voltage reached a certain high level and the circuit behaved not according to ohm's law. Can you give me a reason why?
2007-08-30 14:02:54 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Yes, the circuit DID behave according to Ohm's Law. Someone just did not apply it properly. I assume you are talking about a constant wattage circuit, or else this whole thing does not make sense.
As the voltage rises, the amperage decreases, which decreases the power loss in both the line and the filament. That effect is why long-distance transmission lines are stepped up to, for example, 34,500 volts. Current loss is proportional to amperage, not to voltage or wattage.
Higher voltage = lower amperage = lower current loss.
2007-08-30 14:21:24 · answer #1 · answered by Tom K 6 · 0⤊ 1⤋
Sure. As the filament heats up, its resistance changes. In fact, the resistance increases as the temperature increases. So as the voltage goes up, the lamp gets hot and the resistance increases, hence the current decreases.
2007-08-30 21:11:57 · answer #2 · answered by nyphdinmd 7 · 0⤊ 0⤋
It still obeys Ohm's law. It's just that the resistance of the filament increases with temperature. That's typical of metals.
2007-08-30 22:42:21 · answer #3 · answered by Dr. R 7 · 0⤊ 0⤋
The filament has very little resistance when it is cold, when it heats up the Resistance increases dramatically and this causes a drop in current.
2007-09-02 20:15:04 · answer #4 · answered by johnandeileen2000 7 · 0⤊ 0⤋
It's probably because the resistance of the filament increases with temperature.
2007-08-30 21:11:38 · answer #5 · answered by RickB 7 · 0⤊ 0⤋