Final answer:
The function of a laptop inverter is to convert DC power to AC power, which is necessary for operating components like the laptop screen's backlight. To determine the power used by the laptop screen, the current drawn with the screen on minus the current drawn with the screen off is multiplied by the voltage (16 V). The screen uses 8.0 W of power.
Step-by-step explanation:
The function of a laptop inverter is to convert DC power to AC power. Specifically, an inverter is required when devices such as laptops need to use battery power (which is DC) to operate components that require AC power, like certain types of backlighting used in laptop screens. It is important not to confuse the inverter with other components such as transformers or voltage regulators, which either transform voltage levels or regulate voltage, respectively.
To address the student's homework question: The function that describes the inverter is the first option, converts DC power to AC power.
Now, to measure the power consumed by the laptop screen, we calculate the difference in current drawn when the screen is off and at full brightness, with provided voltage.
Screen off current: 0.40 A
Screen on at full brightness: 0.90 A
Voltage supplied: 16 V
The additional current used by the screen when it is turned on is 0.90 A - 0.40 A = 0.50 A. To find the power used by the screen, we use the formula Power (P) = Voltage (V) × Current (I), so Power used by the screen is 16 V × 0.50 A = 8.0 W.
Therefore, the correct answer is:
- The power used by the screen is 8.0 W.