Final answer:
The power used by the laptop screen can be calculated by subtracting the power consumption with the screen off from the power consumption with the screen on at full brightness. The power used by the screen is found to be 8.0 W by using the formula Power = Voltage × Current.
Step-by-step explanation:
To determine the power used by the laptop screen, we can use the formula for electrical power: Power (P) = Voltage (V) × Current (I). First, we calculate the total power consumption when the screen is on and when the screen is off:
Screen off power consumption: P_off = V × I_off = 16 V × 0.40 A = 6.4 W
Screen on power consumption: P_on = V × I_on = 16 V × 0.90 A = 14.4 W
Now, to find the power used by the screen alone, we subtract the off-power consumption from the on-power consumption:
P_screen = P_on - P_off = 14.4 W - 6.4 W = 8.0 W
Therefore, the correct answer is:
d. The power used by the screen is 8.0 W.