A thermal tap used in certain apparatus consists of a silica rod which fits tightly inside an Aluminium tube whose internal diameter is 8 mm at 0℃ . When the temperature is raised, the fit is no longer exact. Calculate what change in temperature is necessary to produce a channel whose cross-section is equal to that of a tube of 1 mm internal diameter. Α for silica = 8 × 10 − K − 1 , α for Aluminium = 26 × 10 − K − 1