The hot resistance of the bulb's filament is higher than its cold resistance because the temperature coefficient of the filament is _.

Explanation

For conductors ( like filament ) the temperature coefficient is Positive i.e as the temperature increases collision between electrons and protons increases Finally the resistance also increases.A positive temperature coefficient implies that the resistance of the material increases as the temperature rises. This is the case for most metallic conductors, including the filaments used in light bulbs. When the filament heats up and reaches its operating temperature, its resistance increases due to the positive temperature coefficient. Therefore, the hot resistance of the bulb's filament is indeed higher than its cold resistance because of the positive temperature coefficient.