Question

In the experiment of chemical cells, I connected a magnesium electrode , a copper electrode and a multimeter in a complete circuit.

When magnesium electrode is connected to the negative terminal and the copper electrode is connected to positive terminal, the reading of the multimeter is positive.

However, when copper is connected to the negative electrode and magnesium is connected to the positive electrode, the reading is negative instead.

I wonder what "positive" and "negative" reading means. Is it just defined by scientists that a positive voltage reading mean a flow of electrons from negative electrode to positive electrode, or can it be explained with scientific knowledge?

Answer 1

In a galvanic cell, the positive and negative readings on the multimeter indicate the direction of electron flow. Positive voltage readings mean a flow of electrons from the negative electrode to the positive electrode, and negative readings mean a reversed flow.

Step-by-step explanation:

In the experiment of chemical cells, the positive and negative readings on the multimeter indicate the direction of the flow of electrons. When the magnesium electrode is connected to the negative terminal and the copper electrode is connected to the positive terminal, the multimeter reads positive because electrons flow from the negative electrode (magnesium) to the positive electrode (copper).

Conversely, when the copper electrode is connected to the negative terminal and the magnesium electrode is connected to the positive terminal, the multimeter reads negative because the flow of electrons is reversed.

It is not just an arbitrary definition by scientists that positive voltage readings mean a flow of electrons from the negative electrode to the positive electrode. It is based on scientific knowledge and the behavior of electrons in a circuit.

In a galvanic cell, electrons are released at the negative electrode (anode) and attracted to the positive electrode (cathode) due to the difference in electrical potential between the two half-reactions. The direction of electron flow determines the positive or negative reading on the multimeter.