Basic Electricity (what i should know but don't)

[chaz699]

i have been given this question

Figure 1 shows a graph of V against I for a filament lamp. Calculate the maximum resistance of the lamp over the range shown by the graph,

now i have a somewhat vague attempt and its to measure the tangent of the line (i can't upload the graph sorry)

how do i take a tangent of a curved line accurately and then calculate the maximum resistance


thank you for your help

 

[Dadface]

You just need to take a little time and care drawing your tangent.The graph should be steepest at the origin where the resistance is highest..Draw your tangent as long as you can ,construct a right angled triangle where the tangent becomes the hypotenuse and divide the change of voltage by the change of current(tan theta)