Question

The plug-in transformer for a laptop computer puts out 7.50 V and can supply a maximum current of 2.00 A. What is the maximum input current if the input voltage is 240 V? Assume 100% efficiency.

a) 1.00 A
b) 0.50 A
c) 2.00 A
d) 3.20 A

Answer 1

To find the maximum input current, divide the output voltage by the input voltage and multiply by the maximum output current. If the actual efficiency is less than 100%, the input current would need to be greater to compensate for power losses.

Step-by-step explanation:

To find the maximum input current, we can use Ohm's law which states that current (I) is equal to voltage (V) divided by resistance (R). In this case, the resistance is the input current. We are given the output voltage of 7.50 V and maximum output current of 2.00 A. So, I = V / R, where I = 2.00 A and V = 7.50 V. Rearranging the equation, we find that R = V / I. Therefore, the maximum input current is 7.50 V / 240 V * 2.00 A = 0.625 A.

If the actual efficiency is less than 100%, the input current would need to be greater. This is because a lower efficiency means that more power is being lost as heat or other forms of energy, resulting in a decrease in output power. To compensate for this, the input current needs to be increased to ensure enough power reaches the intended load.