A 6.0W bulb is connected to a source of 480J of energy. Assuming the system is 100% efficient, and the bulb runs at full power, how long can it stay lit?
- Bulb power = 6.0W - Energy provided = 480J - Use equation P = E / t (Power = energy/time) where power is in watts, energy is in joules, and time is in seconds - Rearrange the equation to give t = E / P (time = energy/power) to find the time in seconds - Plug in the values to give t = 480/6 = 80 - Therefore time = 80 seconds.
