# On error analysis of my practical

1. Jan 30, 2007

### Delzac

[Urgent]On error analysis of my practical

1. The problem statement, all variables and given/known data
well, the aim of the practical is to calculate the speed of light using LED, oscilloscope and varying fiber optics cable.

i have my results as follows :

L /m t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 taverage

5.00 (28 30 28 28 28 28 28 28 30 28) 28.4

10.00 (60 62 60 60 60 60 60 60 60 60) 60.2

15.00 (76 76 78 76 76 76 76 76 76 76) 76.2

20.00 (102 100 102 102 102 102 102 102 100 102) 101.6

The equation used is $$c = n \frac{\lambda}{t}$$

We are to plot a graph of L versus time.

The problem now is calculating the error of y.

Do we use

Least Square Method( where $$\sigma_i = \sigma$$) OR
Least Square Method( Where each y, has its own $$\sigma_i$$)

We know that L is the y axis in this case, however no multiple values of L has been taken. So every y, has the same $$\sigma$$. However, time has been taken mutiple times, do we use LSM(Where each y, has its own $$\sigma_i$$) on it? But time is the x-axis in this case.

So what should i use or do?

Any help will be appreciated. Thanks

Last edited: Jan 30, 2007
2. Jan 30, 2007

### Delzac

Anyway, since gradient is speed of light, the graph has to be a straight line.