What are the "following" devices ? ?
I think they're a list of choices that you have but aren't sharing.
A few devices associated with the reception of various types of
radio signals include the resonant tank, the local oscillator, the
mixer, the detector, the coherer, the discriminator, the parabolic
reflector, the lecher wires, the audio transducer, the demultiplexer,
and ... my personal guess ... the 'antenna' or 'aerial'.
Explanation:
(1). Formula to calculate the potential difference is as follows.
= 
= 
= 
= 
= 38.7 volts
Therefore, magnitude of the potential difference between the two spheres is 38.7 volts.
(2). Now, formula to calculate the energy stored in the capacitor is as follows.
E = 
= 
= 
Thus, the electric-field energy stored in the capacitor is
.