Question

Lidia plans an experimental investigation to see how the thickness of a lens affects the point where a beam of light is focused. She plans to shine light through a lens and measure the distance to a screen that is placed where the beam focuses. What are the controls in Lidia’s investigation?

Answer 1

Since Lidia plans to measure the point where the beam of light is focused, then the controls in this setup would be the position of the lens from he beam of light, as well as the distance of the lens from the screen. This is because we only need to switch the lens' thickness and not the position itself.

Answer 2

Answer: the type of light and the material of the lens.

Step-by-step explanation:

1) Since the investigation is aimed to determine how the thickness of a lens affects other variable, the thickness the lense is the independent variable.

This is, LIdia has to experiment with several thicknesses to find later the effect on the dependent variable.

2) Since the investigation is aimed to determined how the point where a beam of light is focused, this is the dependent variable, which means that she does not have control over it, but she will only observe and measure how it responds to the changes on the independent variable.

3) To draw a conclusion, Lidia needs to make sure that other variables are not affecting the results or output, which is the point where the beam of light is focused. That is why she has to control other variables. This is, she has to make sure that the type of light and the material of the lens remain constant, else she will not be able to discriminate the effect of the thickness of the lens from other causes.