Intelligent assessment and revision tools for OCR A Physics

In a lab to determine the Young modulus of a metal wire by adding masses and measuring its extension, you want to reduce the percentage uncertainty in the extension reading without changing the measuring scale or the mass steps. Which change to the setup is best?

• A Use a shorter, thicker steel wire so it stays stiff and the extension is small.
• B Replace the steel wire with a rubber cord so the extension is much larger for the same mass.
• C Use a longer, thinner steel wire so the extension for each added mass is larger and easier to read.
• D Hang two identical steel wires in parallel to share the load, reducing the strain on each.