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 lidias investigation? the material and thickness of the lens the type of light and the material of the lens the distance to the screen and the type of light the thickness of the lens and the distance to the screen

Explanation:

In an experimental investigation, controls are the variables kept constant to ensure a fair test. Here, the independent variable is the lens thickness (what's being changed), and the dependent variable is the focus distance (what's being measured). To isolate the effect of lens thickness, other variables like the type of light (e.g., laser, LED) and the lens material should be kept constant. Let's analyze each option:

• Option 1: Thickness is the independent variable (changed), so it's not a control. Eliminate.
• Option 2: Type of light and lens material are kept constant to avoid affecting the focus distance, so these are controls. This makes sense.
• Option 3: Distance to the screen is the dependent variable (measured), not a control. Eliminate.
• Option 4: Thickness is independent (changed) and distance is dependent (measured), so neither are controls. Eliminate.

Answer:

B. the type of light and the material of the lens