Calculate radiation power for sphere whose temperature is 227$$^\circ$$C, radius 2 m and emissivity 0.8.

If two protons are moving with speed $$v=4.5 \times 10^5 \mathrm{~m} / \mathrm{s}$$ parallel to each other then find the ratio of electrostatic and magnetic force between them

An ideal gas initially at pressure 1 bar is being compressed from $$30 \mathrm{~m}^3$$ to $$10 \mathrm{~m}^3$$ volume and its temperature decreases from $$320 \mathrm{~K}$$ to $$280 \mathrm{~K}$$, then find final pressure of the gas.

A current of $$10 \mathrm{~A}$$ is passing through a metallic wire of cross-sectional area $$4 \times 10^{-6} \mathrm{~m}^2$$. If the density of the aluminium conductor is $$2.7 \mathrm{~gm} / \mathrm{cc}$$ considering aluminium gives 1 electron per atom for conduction, then find the drift velocity of the electrons if molecular weight of aluminium is $$27 \mathrm{~gm}$$.