The Young modulus of the material of a wire can be determined using the apparatus shown in Fig. 3.1. [Figure 3.1] One end of the wire is clamped at C and a marker is attached to the wire above a scale S. A force to extend the wire is applied by attaching masses to the other end of the wire. The reading X of the marker on the scale S is determined for different forces F applied to the end of the wire. The variation with X of F is shown in Fig. 3.2. [Figure 3.2]

1. (a)The length of the wire from C to the marker for F = 0 is 3.50 m. The diameter of the wire is 0.38 mm. Use the gradient of the line in Fig. 3.2 to determine the Young modulus E of the material of the wire in TPa.[3]
2. (b)The experiment is repeated with a thicker wire of the same material and length. State how the range of the force F must be changed to obtain the same range of scale readings as in Fig. 3.2.[1]

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