Why is there no electric field at the center of a charged spherical conductor?

Energy is the ability to do work which measures what

Argon is adiabatically compressed from an initial volume of 16 liters to a final volume of 2 liters. by what factor do the following quantities change? do they increase or decrease? (a) the rms speed (b) the thermal energy of the gas (c) the molar specific heat cv (d) the pressure

Place me with this question is my last question