>>51
語源に興味があるなら　「radio etymology 」でググると色々見つかる。
気になる単語があったら、覗いてみればいい、↓こんな事が書いてる。

radio (n.)
"wireless transmission of voice signals with radio waves," 1907,
abstracted from earlier combinations such as radio-receiver (1903), radiophone (1881), radio-telegraphy (1898),
from radio- as a combining form of Latin radius "beam." 　←
Use for "radio receiver" is first attested 1913; sense of "sound broadcasting as a medium" is from 1913.
＞radiusですかね？半径
radius の　"bea,m"に語源を求めてるね。


放射能の「被ばく」は radiation という単語がある。
radiation (n.)
mid-15c., "act or process of radiating," from Middle French radiation and directly from Latin radiationem (nominative radiatio)
"a shining, radiation," noun of action from past participle stem of radiare
"to beam, shine, gleam; make beaming," from radius ←
"beam of light; spoke of a wheel" (see radius). Meaning "rays or beams emitted" is from 1560s.
Meaning "divergence from a center" is 1650s.

いわゆる「ラジオ」として考えてるなら、商標だったりするから、まず日本語で確かめた方がいいかも。
英文が分からなければ、書いてくれれば説明するから聞いて。
radio の方のradio-receiver (1903)　がキーワードで、質問の答えになってると思う。