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
A
the material and thickness of the lens
B
the type of light and the material of the lens
C
the distance to the screen and the type of light
D
the thickness of the lens and the distance to the screen
Explanation
The thickness of the lens is the variable Lidia changes, and the distance to the screen is what she measures as the result. Controls are factors kept the same so the test is fair. She should keep the type of light and the lens material constant, so the correct choice is the type of light and the material of the lens.
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