There are four methods to measure the electromotive force and internal resistance of power supply: Voltammetry (relative power supply external connection), Voltammetry (relative power supply internal connection), Amplitude resistance method and Voltammetry. We analyze the error analysis of Voltammetry relative power supply internal connection and external connection from two methods: mirror image method and equivalent power supply method.

Impedance method

The experimental circuit diagram is shown above.

According to Ohm theorem of closed circuit:

E=I(R+r)？ ( 1)

Among them? e？ It is the electromotive force of the power supply. r？ Is the internal resistance of the power supply. Me? For ammeter reading,? r？ It's the resistance reading of the resistance box.

In the experiment, the electromotive force and internal resistance of power supply are measured mainly by ammeter reading and resistance reading of resistance box.

Convert (1) to:

1I= 1E R+rE？ (2)

1I？ r？ The image is as follows:

As shown in the above figure, the intersection of the image and the horizontal axis is r? (the internal resistance is negative), and the intersection with the longitudinal axis is? rE？ (ratio of internal resistance to electromotive force), with a slope of? 1E？ (back electromotive force).