The inner rim of the dish contains an earthed metal ring. Above the centre of the dish there is a metal needle which does not touch the oil surface. Powder conductivity Measure and explain the conductivity of a mixture of metallic and dielectric powders with various proportions of the two components. Prepare a rope from fibers and investigate its tensile strength. Water rise Immerse the end of a textile strip in water.
Luminescent sugar Investigate and explain the light produced when sugar crystals are pulverized.
Strange motion Make a mixture of ammonium nitrate and water, proportion 5 to 1. When the mixture is heated to about 100 C it melts. When it cools, it crystallizes and you may observe a strange motion below the surface. Investigate and explain the phenomenon. Icicles Investigate and explain the formation of icicles.