Water conducts electricity primarily through the movement of charged particles called ions, which are dissolved impurities found in it.
The Role of Charged Particles
According to the reference provided, in order for electricity to flow through a liquid, movement of charges must take place in the liquid. Pure water (H₂O) itself is a poor conductor of electricity because its molecules are neutral and there are very few free ions naturally present.
However, the water we commonly encounter – whether tap water, rainwater, or seawater – is far from pure.
Impurities Bring the Charges
The reference highlights that these types of water contain innumerable impurities. These impurities include substances that dissolve and break apart into ions. Ions are atoms or molecules that have gained or lost electrons, giving them a net electrical charge.
Examples of such impurities mentioned are:
- Sodium ions (Na⁺)
- Calcium ions (Ca²⁺)
- Magnesium ions (Mg²⁺)
These dissolved ions carry electrical charges. When an electric voltage is applied across the water (like when a device is plugged in near water, or if lightning strikes), these charged ions are compelled to move. Positive ions move towards the negative electrode, and negative ions move towards the positive electrode.
How Ion Movement Facilitates Conduction
It is this movement of charges – the flow of these dissolved ions through the water – that constitutes an electric current. The more dissolved ions present in the water, the greater its conductivity, and the more easily electricity can flow through it.
This is why:
- Pure or distilled water is a very poor conductor.
- Tap water conducts electricity due to minerals and salts dissolved in it.
- Seawater is an excellent conductor because it contains a very high concentration of dissolved salts (like sodium chloride, which separates into sodium ions and chloride ions).
In summary, water doesn't conduct electricity by itself in its purest form, but it becomes a conductor when it contains dissolved impurities that form mobile ions. The flow of these charged ions allows the electric current to pass through the liquid.
