Question

Plot graph between 1/v and 1/u for a concave mirror and then evaluate focal length by graph

Answer 1

concave mirror U-V method:
After doing the experiment to find the focal length of given concave mirror.

Note Down  the value of u,v in a observation  table

Finding Focal length by plotting graph between 1/u and 1/v :

Step 1 :
Plot the graph for 1/u along x axis and 1./v along y axis .

Step 2:By sign conventions 1/u will be negative and 1/v will be negative.Plot the various points for different set of values of 1/u and 1/v from the observation table  in third quadrant

Step 3:

The graph is straight line  intercepting the axis at X1 and Y1  at an angle 45 degree at points A and B .It makes equal intercepts.

Calculations :Measure the distance OA and OB

OA=-------cm
OB= ---------cm

Then focal length= -1/OA= -1/OB
= --   ---------cm