Answer:
RL=100K → Vo=9.90 mV
RL=10K → Vo=9.09 mV
RL=1K → Vo=5 mV
RL=100 → Vo=909.09 μV
In order to obtain 80% of the power source we have to put a resistor of 4 KOhm.
Step-by-step explanation:
Here we have a power source in serie with a resistor of 1K and RL, in order to obtain the Vo voltage we have to apply the voltage divider rule, that states:
Substituing the resistor values of RL we obtained the following results:
RL=100K → Vo=9.90 mV
RL=10K → Vo=9.09 mV
RL=1K → Vo=5 mV
RL=100 → Vo=909.09 μV
In order to find the lowest value that gives us 80% of the source voltage we have to use the voltage divider rule again and make the Vo equal to 0.8 Vin:
The result of the last equation is 4000, so in order to obtain 80% of the power source we have to put a resistor of 4 KOhm.