A tungsten cube of side 2 cm has a resistance of 2.8 μΩ - Leaving Cert Physics - Question 1 - 2022

The resistivity ($\rho$) is calculated using the formula:

$\rho = R \cdot \frac{A}{L}$

Where:

• $R$ is the resistance (2.8 μΩ = $2.8 \times 10^{-6} \Omega$)
• $L$ is the length, which in this case, for a cube, is the same as the side length (0.02 m)

Substituting the values:

$\rho = (2.8 \times 10^{-6} \Omega) \cdot \frac{0.0004 ext{ m}^2}{0.02 ext{ m}}$

Simplifying this gives:

$\rho = 0.000000028 \cdot 0.02 = 5.6 \times 10^{-6} \Omega \cdot m$