inner walls of the tube. Note down the reading ( L ) ¾ Turn the microscope screws in horizontal direction to view the right side inner wall of the tube. Note the reading (R ). Thus the radius of the tube can be calculated as ( ) .
¾ Finally calculate the surface tension using the given formula. 2r 2r RADIUS OF THE CAPILLARY TUBE L R OBSERVATIONS To measure height of the liquid (h) Least count of the microscope = cm UNIT- (XI- - ) PRACTICAL FIRST UNIT- (XI- - ) PRACTICAL FIRST - - - - Practical Trial No. Microscope reading for the position of Lower meniscus of liquid Microscope reading for the position of Lower tip of the needle Height of the liquid h × − m a ~ b MSR VSC × LC = VSR TR (a) × − m MSR VSC × LC = VSR TR (b) × − m Mean h = Radius of the capillary tube Tube Microscope reading for the position of inner left wall of the tube L Microscope reading for the position of inner right wall of the tube R Radius of the capillary tube r = (L ~R ) × − m MSR VSC × LC = VSR TR × − m MSR VSC × LC = VSR TR × − m CALCULATION Mean rise of the liquid in the capillary tube h = × − m Diameter of the capillary tube 2r = × − m Radius of the capillary tube r = × − m Density of the liquid σ = kg m - Acceleration due to gravity g = . m s - Surface tension hrσg = N m – RESULT Surface tension of the given liquid by capillary rise method T = N m – UNIT- (XI- - ) PRACTICAL FIRST UNIT- (XI- - ) PRACTICAL FIRST - - - - Practical