Explain detection of electromagnetic waves

Radio waves are detected using electrical circuits that receive these electromagnetic signals in an antenna, and then the radio frequencies are modulated through capacitors before emerging as sound in a speaker. Radio waves are normally less than a kilohertz long up to 20 gigahertz.

what type of charge does it have? negative

d

explanation:

v=uf/(u-f)

= 5.10/(5-10) convex lens has positive focal length

=50/-5

=-10 cm (formed at other side)