What property of a light bulb's filament causes it to glow?
1. high voltage
2. high resistance
3. low resistance
4. low voltage



Answer :

AL2006
You can toss out choices 1). and 4). right away, because voltage is whatever is applied to the bulb from the outside, and is not a property of the filament.

The power dissipated by anything that conducts a current can be written as

Power = (voltage across the component)² / (resistance of the component) .

Since the resistance is in the denominator of the fraction, lower resistance dissipates higher power.  The resistance of the light bulb's filament is made so low that when current flows through it, it dissipates enough energy to get hot and also to even produce some visible light.

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