Context: The first successful light bulb filaments were made of carbon (from carbonized paper or bamboo). Early carbon filaments had a negative temperature coefficient of resistance — as they got hotter, their electrical resistance decreased. This made the lamp sensitive to fluctuations in the power supply, since a small increase of voltage would cause the filament to heat up, reducing its resistance and causing it to draw even more power and heat even further. In the "flashing" process, carbon filaments were heated by current passing through them while in an evacuated vessel containing hydrocarbon vapor (usually gasoline). The carbon deposited on the filament by this treatment improved the uniformity and strength of filaments as well as their efficiency. A metallized or "graphitized" filament was first heated in a high-temperature oven before flashing and lamp assembly. This transformed the carbon into graphite which further strengthened and smoothed the filament. This also changed the filament to have a positive temperature coefficient, like a metallic conductor, and helped stabilize the lamp's power consumption, temperature and light output against minor variations in supply voltage.

Question: What material were the first light bulb filaments made from?
Answer: carbon

Question: What was the primary problem with early carbon filaments?
Answer: as they got hotter, their electrical resistance decreased

Question: What were the positive effects of the flashing process?
Answer: improved the uniformity and strength of filaments as well as their efficiency

Question: What properties of graphite improved the filament?
Answer: further strengthened and smoothed the filament

Question: What are the effects of giving the filament a positive temperature coefficient?
Answer: helped stabilize the lamp's power consumption, temperature and light output against minor variations in supply voltage

Question: What were the first failed light bulb filaments made from?
Answer: Unanswerable

Question: What had a positive temperature coefficient of resistence?
Answer: Unanswerable

Question: What was not a problem for early carbon filaments?
Answer: Unanswerable

Question: What were negative effects of the flashing process?
Answer: Unanswerable

Question: What did not further strengthen and did not smooth the filament?
Answer: Unanswerable