The electricfield within a closed, empty conductor is zero, so the cup shields the object placed inside it from any atmospheric or stray electric fields.
There is an electricfield in atmospheric and it can be influenced by the conductor in the field.
大气中存在大气电场，地面上的导体对大气电场会发生影响。
3
Radiant power of atmospheric radio noise and electricfield intensity is computed precisely for given maritime space, and then the computational way of radiant power is given.