Question 17

The light bulb was on for 8 hours.

To determine how long the 60W light bulb was on using 0.48 kilowatt hours of electricity, we can apply the formula that relates power and energy usage. The bulb, consuming 60 watts (or 0.06 kilowatts), indicates that if it used 0.48 kilowatt hours, it must have been on for 8 hours.

A) 0.48 hours

This option is incorrect because 0.48 hours is equivalent to approximately 29 minutes. Given the power of the bulb, it would consume much more energy in such a short time.

B) 28.8 hours

This option is also incorrect. A calculation would show that for a 60W bulb to use 0.48 kWh over 28.8 hours would not match the energy consumption rate, as that would indicate a much lower wattage.

C) 0.125 hours

This choice is incorrect as well. 0.125 hours equals 7.5 minutes, which would not correspond to the energy used by the bulb, as it would consume only a fraction of the total 0.48 kWh in that time.

D) 8 hours

This option is correct. By dividing the total energy used (0.48 kWh) by the power of the bulb (0.06 kW), we find that the bulb was indeed on for 8 hours, as the calculation yields exactly this duration.

Conclusion

The correct duration of 8 hours accurately reflects the energy consumption of the 60W bulb operating at 0.48 kilowatt hours. All other options fail to provide a feasible timeframe based on the power and energy relationship, confirming that D is the only valid answer.