Energy Conservation in a Light Bulb
How does the law of conservation of energy apply to a light bulb?
Which of the following statements accurately describes the application of the law of conservation of energy to a light bulb?
A. The electrical energy put into the light bulb equals the light energy coming out of the light bulb
B. The electrical energy put into the light bulb equals the electrical energy coming out of the light bulb
C. The total energy put into the light bulb equals the total energy coming out of the light bulb
D. The electrical energy put into the light bulb equals the heat energy coming out of the light bulb
Final answer:
The total energy put into the light bulb is equal to the total energy coming out in the form of light and heat. The electrical energy is transformed due to the resistance of the bulb's filament, following the formula Power = Voltage x Current.
Explanation:
The law of conservation of energy applies to a light bulb by stipulating that the total energy put into the light bulb equals the total energy coming out of the light bulb in different forms. When electrical energy is supplied to a light bulb, it is converted into light energy and heat energy. For example, a 60-watt light bulb not only emits more light but also produces more heat compared to a 25-watt light bulb, which indicates the transformation of electrical power into light and heat.
The relationship of voltage, current, and resistance to electric power is explained by the formula Power (P) = Voltage (V) x Current (I), where resistance is inversely proportional to current, given by Ohm's law as V = I x R. The electric power consumed by a light bulb, measured in watts, manifests as both light and thermal energy due to the resistance encountered by the current flowing through the bulb's filament.