Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds
 

Oil film kit

The Oil film kit includes the following: 

  • special trays with rubber bungs for drain holes and 4 rubber wedges for each tray 
  • lycopodium powder dispensers with cheesecloth covers secured with rubber bands 
  • 2 metal booms per tray 
  • class set of special holders with magnifying glasses and 0.5 mm graticules 
  • class set of 2 mounted wire loops 
  • beaker, 10 ml 

Technical notes

The trays should have a layer of black paraffin wax painted on their bottoms, their sides and – especially carefully – their top rims. The booms should also be coated with wax. This should be done at least a day prior to use. Melt the paraffin wax in a can and add a little of the vegetable black. 
 
When the liquid is hot – almost but not quite smoking – paint it on the tray with the soft paint brush. (Any thick blobs of wax that form on the rim can be dispersed by repainting with a brushful of very hot, molten wax. Do not use a Bunsen flame as it may cause damage or add grease. If any difficulty is experienced waxing the trays it is almost certainly due to not having the wax hot enough.) 
 
The wire loops should be of stainless steel, diameter 0.008 cm.