A 12-volt direct current, 13-watt fluorescent light is controlled by a photocell. How many watt-hours are consumed by the light on an average day if it is on for 12 hours?

A 12-volt direct current, 13-watt fluorescent light is controlled by a photocell. How many watt-hours are consumed by the light on an average day if it is on for 12 hours?

• A. 156 watt-hours
• B. 130 watt-hours
• C. 120 watt-hours
• D. 144 watt-hours

Answer: (A)

To determine the watt-hours consumed by the fluorescent light when it operates under specific conditions, consider the formula for calculating watt-hours:

Watt-hours (Wh) = Power (in watts) × Time (in hours).

In this scenario, the fluorescent light has a power rating of 13 watts and is turned on for an average of 12 hours per day. By applying the formula, multiply the power consumption by the hours of operation:

13 watts × 12 hours = 156 watt-hours.

Therefore, the total energy consumed by the light over an average day is 156 watt-hours. This highlights the direct relationship between the power rating of an electrical device and the time it runs, emphasizing how these factors combine to calculate overall energy usage in watt-hours.