A student used the apparatus shown to determine the Young modulus of brass. Loads were added to the test wire and corresponding readings taken from the vernier scale. The test wire and the reference wire were identical. (a) (i) Give one advantage of using a reference wire as well as a test wire. (ii) State why a reference load was applied to the reference wire. (b) Explain why the test wire should be both long and thin. (c) The student varied the load F on the test wire and recorded the corresponding change in length Δx from the vernier scale. The results are shown on the graph. Determine a value for the Young modulus of brass. length of wire = 2.75 m diameter of wire = 5.60 × 10⁻⁶ m

A-Level Edexcel Physics Materials: A student used the apparatus sho

A student used the apparatus shown to determine the Young modulus of brass - Edexcel - A-Level Physics - Question 5 - 2023 - Paper 3

Question 5

A student used the apparatus shown to determine the Young modulus of brass. Loads were added to the test wire and corresponding readings taken from the vernier scale... show full transcript

Worked Solution & Example Answer:A student used the apparatus shown to determine the Young modulus of brass - Edexcel - A-Level Physics - Question 5 - 2023 - Paper 3

Step 1

Give one advantage of using a reference wire as well as a test wire.

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Answer

Using a reference wire alongside a test wire helps minimize errors caused by bending or external disturbances, ensuring more accurate measurements of the load and extension.

Step 2

State why a reference load was applied to the reference wire.

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Answer

A reference load is applied to the reference wire to ensure it remains taut and straight during the experiment, providing a stable baseline for measurements.

Step 3

Explain why the test wire should be both long and thin.

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Answer

A long test wire has a greater extension for a given load, allowing for more precise measurements of strain. A thin wire, on the other hand, can sustain higher stress, reducing the risk of material failure during the experiment.

Step 4

Determine a value for the Young modulus of brass.

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Answer

To calculate Young's modulus, we first determine the gradient from the graph which represents the ratio of force to extension.

Determine the gradient:
- The gradient is calculated as the change in extension Δx divided by the change in force F, i.e., $ext{Gradient} = rac{ ext{Δ}x}{ ext{Δ}F}$
- Using values from the graph, identify points for Δx and ΔF and substitute them accordingly.
Calculate Young's modulus:
- Using the formula for Young's modulus, we have: $E = rac{F}{A rac{Δx}{L}}$
- Where A is the cross-sectional area of the wire, calculated as: $A = rac{ ext{π}}{4}d^2$
- Substitute the diameter of the wire and calculated values into the formula to find E.

This results in a calculated Young's modulus value of approximately $1.057 × 10^{11} ext{ N/m}^2$ .

A student used the apparatus shown to determine the Young modulus of brass - Edexcel - A-Level Physics - Question 5 - 2023 - Paper 3

Worked Solution & Example Answer:A student used the apparatus shown to determine the Young modulus of brass - Edexcel - A-Level Physics - Question 5 - 2023 - Paper 3

Give one advantage of using a reference wire as well as a test wire.

State why a reference load was applied to the reference wire.

Explain why the test wire should be both long and thin.

Determine a value for the Young modulus of brass.

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