Electricity and Magnetism
# Resistors

If a current of $4.00\text{ A}$ flows in a copper wire with a cross-sectional area of $2.70 \times 10^{-6}\text{ m}^2$ and a length of $5.40\text{ m},$ approximately how much electrical energy is transferred to thermal energy in $15\text{ min}?$

The resistivity of copper is $1.69 \times 10^{-8}\,\Omega\cdot\text{m}.$

A Nichrome wire that has a cross sectional area of $2.50 \times 10^{-6}\text{ m}^2$ is connected to a potential difference of $75.0\text{ V}.$ If the wire dissipates $4000\text{ W},$ what is its approximate length?

Nichrome has a resistivity of $6.00 \times 10^{-7}\,\Omega\cdot\text{m}.$