Figure represents the extension ($$\Delta l$$) of a wire of length 1 meter, suspended from the ceiling of the room at one end with a load W connected to the other end. If the cross-sectional area of the wire is $$10^{-5}$$ m$$^2$$ then the Young's modulus of the wire is __________ N/m$$^2$$.

$$Y = \frac{\text{Stress}}{\text{Strain}} = \frac{W / A}{\Delta l / l} = \frac{W \cdot l}{A \cdot \Delta l}$$

From the given linear graph, picking a clear coordinates point $$(W, \Delta l)$$:

Load ($$W$$) = $$20\text{ N}$$, Extension ($$\Delta l$$) = $$2 \times 10^{-4}\text{ m}$$

$$Y = \frac{20 \times 1}{10^{-5} \times (2 \times 10^{-4})}$$

$$Y = \frac{20}{2 \times 10^{-9}} = 10 \times 10^{9} = 1.0 \times 10^{10}\text{ N/m}^2$$