Green light shines through a 100-mm-diameter hole and is observed on a screen. If the hole diameter is increased by 20%, does the circular spot of light on the screen decrease in diameter, increase in diameter, or stay the same

For this case we can use the model given by:

Where K is a constant and we can see W represent the spot of light and if D increases then W needs to decrease since the other variables remains constant.

Conclusion: The circular spot of light on the screen increase in diameter.

Explanation:

For this case we know that the diameter is:

And the hole diameter is increased by 20%, so the final diameter would be:

And for this case if we use concepts from the theory of rays we know that if the diameter of the hole gets bigger then the hole wuld increase.

For this case we can use the model given by:

Where K is a constant and we can see W represent the spot of light and if D increases then W needs to decrease since the other variables remains constant.

Conclusion: The circular spot of light on the screen increase in diameter.