Tin foil hat radio with a metal bucket. The AM radio is completely inside a metal enclosure. This leads to a noticeable reduction in signal strength received by the AM radio. The efficiency of a metal enclosure in blocking electromagnetic radiation depends on the thickness of the foil, as dictated by the "skin depth" of the conductor for a particular wave frequency range of the radiation. For half-millimetre-thick aluminum foil, radiation above about 20 kHz (i.e., including both AM and FM bands) would be partially blocked, although aluminum foil is not sold in this thickness, so numerous layers of foil would be required
What Are Little Boys Made Of? What Are Little Boys Made Of? "What Are Little Boys Made Of?" is a popular nursery rhyme dating from the early 19th century. It has a Roud Folk Song Index number of 821. The author of the rhyme is uncertain, but may be English poet Robert Southey (1774–1843). Here is a representative modern version of the lyrics: <poem> What are little boys made of? What are little boys made of? That's what little boys are made of What are little girls made of? What are little girls made of? That's what little girls are made of</poem> The rhyme appears in