[amp_mcq option1=”20 Ohm” option2=”30 Ohm” option3=”10 Ohm” option4=”100 Ohm E. None of the above” correct=”option1″]
The correct answer is: A. 20 Ohm
A voltage source is said to be stiff if the change in its output voltage is small when a load is connected to it. The smaller the source resistance, the stiffer the voltage source.
In this case, the source resistance is 0.2 Ohm. If the load resistance is 20 Ohm, the output voltage will be 15V. If the load resistance is 30 Ohm, the output voltage will be 14.7V. If the load resistance is 10 Ohm, the output voltage will be 14.3V. If the load resistance is 100 Ohm, the output voltage will be 13.5V.
Therefore, the voltage source will appear stiff when the load resistance is 20 Ohm.
Option B is incorrect because the output voltage will be 14.7V when the load resistance is 30 Ohm. This is not a small change in voltage.
Option C is incorrect because the output voltage will be 14.3V when the load resistance is 10 Ohm. This is not a small change in voltage.
Option D is incorrect because the output voltage will be 13.5V when the load resistance is 100 Ohm. This is not a small change in voltage.
Option E is incorrect because the voltage source will appear stiff when the load resistance is 20 Ohm.