An alternate method to access flash content 

Simulation link: https://vlab.amrita.edu/repo/PHY/OPT/CornusMethod/CornusMethod.swf

 

 Procedure

 

1. Real lab

 

To find the diametre of rings without mass

 

 

1. Place the given Perspex beam symmetrically over the two knife edges.
2. A convex lens is placed over beam.
3. As shown in figure light is allowed to fall normally on the air film with the help of glass plate.
4. On focusing, interference fringes formed are viewed by means of travelling microscope.
5. Fix the cross wire on any of the nth ring on one side (left or right) using the knob.
6. Corresponding value of MSR and VSR is noted.
7. Move the cross wire to the (n-1)^th or (n-2)^nd ring on the same side.
8. Take the readings of the rings on either side of the centre position.
9. Now repeat the same procedure by moving the cross wire up and down on either side of centre position.
    

   

 

 

Diametre of rings with mass

 

1. Adjust the distance between the weight hanger and the knife edges.
2. Add mass on the weight hanger.
3. Repeat steps 4-9 to measure the horizontal and vertical position of rings.
    

 

 

 

2. Simulator

 

To find the diametre of rings without mass

 

1. Mass on weight hanger is set as zero g.
2. Select desired values for the variables by clicking on the sliders for each variable.
3. Click on the ‘Light On’ button.
4. Now the repeat the steps 5-9 of real lab.
5. The reading of rings during the horizontal/vertical motion is shown by the horizontal/vertical position value of microscope under variables section.
6. Click ‘Reset’ button for another values of variables
    

To find the diametre of rings with mass

 

1. Adjust the variables and position of weight hanger by clicking on their corresponding sliders.
2. Add suitable mass on weight hanger.
3. Repeat steps 3-6 of simulator.

 

Observations

 

To find the thickness of Perspex beam using screw gauge

 

                                                         Zero correction=

                                                                    Thickness of Perspex beam, b=………..mm

 

 

To find the breadth of Perspex beam using Vernier calipers

 

                                                        Breadth of plate, a=…………cm

 

To find the diameter of rings in horizontal direction

 

 

                                           λ=………..nm, l=………cm

 

                                  Longitudinal bending R₁ = 

 

To find the diameter of rings in vertical direction

 

 

                           Lateral strain, R₂  = 

 

Results

 

For a given plate

 

1. Young’s modulus, Y=………………Nm-²
2. Poisson’s ratio, σ =…………………
3. Bulk modulus, b =………………….. Nm-²