Final answer:
The question asks for the metabolic power usage while running a laptop charger, but none of the provided options directly address this issue without the laptop charger wattage known. For the power consumed by the laptop screen, the correct calculation shows an increase of 8.0 W when the screen is at full brightness.
Step-by-step explanation:
The question appears to be related to the conversion of energy and how it's measured when considering devices and the human body. When calculating metabolic power usage while running a laptop charger, the student is asked to select a true statement.
However, from the options provided, none directly answer the question about metabolic power usage while running a laptop charger, mainly because the laptop charger wattage is not given and the efficiency of the human body and the generator are not considered in the options. To assess power usage, you would need to know the power rating of the laptop charger and the efficiency with which the human body could generate the equivalent power.
That said, for assessing the power used by the screen of a laptop computer, given the current drawn and voltage, we can use the formula Power (P) = Voltage (V) x Current (I). To find the power used by the screen when it goes from off (drawing 0.40 A) to full brightness (drawing 0.90 A) at 16 V, we calculate the difference in power. Screen power consumption increases by (0.90 A - 0.40 A) * 16 V = 0.50 A * 16 V = 8.0 W, so the correct answer to that part is (d).