Why your coffee makes a weird sound - The Hot Chocolate Effect

Make some instant coffee, give it a stir then tap the rim of the mug. You'll notice a steady rising in pitch. Listen to our Domestic Science radio show here: http://festivalofthespokennerd.com/tv-radio/ Visit my blog here: http://stevemould.com Follow me on twitter here: http://twitter.com/moulds Buy nerdy maths things here: http://mathsgear.co.uk