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.

Lidia investigation the type of light and the material of the lens.

Explanation:

Since the purpose of the investigation is to determine how the thickness of the lens affects other variables, the thickness is an independent variable.  so, Lydia experimented with multiple herds to find the next effect on the dependent variable.The purpose of the investigation is to determine at what point the light beam is concentrated, which is a dependent variable, meaning she has no control over it, but only observes and measures how it responds to changes. Independent variable. To conclude, Lydia must ensure that other variables do not affect the result or output, which is where the light beam is concentrated. That is why he has to control other variables. That is, he must see to it that the type of light and the content of the lens are constant, otherwise he cannot explain the effect of the lens thickness for other reasons.