Investigating Internal Resistance (4.1)

Question 1

What is the set up for the internal resistance investigation?

Answer 1

cell in series with a variable resistor and an ammeter. Voltmeter attached across variable resistor

Question 2

How do you obtain results for the Internal Resistance practical?

Answer 2

Vary the current in the circuit by adjusting the load resistance. Record V and I in a table

Question 3

How do you obtain e.m.f and internal resistance from a graph of V (y-axis) against A (x-axis)?

Answer 3

e = V + Ir

1) Rearrange to give V = -rI + e
2) Since e and r are constants, the equation is y = mx + c
3) So the y-intercept is the e.m.f, e
4) And the gradient is -r (internal resistance)