Calculate the minimum breakdown voltage required between $2$ flat electrodes, sealed in nitrogen at $1$ atm pressure. The electrodes are $0\mathrm{.}03$ inch apart. Solve Paschens' equation to find minimum breakdown voltage at sea level, at $50000$ ft altitude and at $70000$ ft altitude. Give equation to find out the minimum electrode gap at any particular altitude and pressure. Consider the material of electrode be silver and electrode dia to be $1\mathrm{.}5$ mm$.$