Physics trivia

Five Things You Probably Didn’t Know About Electricity

Electricity is present in our daily lives and is responsible for several phenomena that intrigue us.

1st) Human skin is very insulating (if dry)

Human skin has an extremely high electrical resistance , measured in ohms (Ω), on the order of 100,000 Ω. As a consequence, the electric current formed by the body when exposed to a 220 V shock is approximately 0.002 A. However, if the skin is wet , its electrical resistance is reduced to only 1000 Ω. In this case, an electrical discharge of 220 V can promote an electrical current of 0.2 A , possibly fatal. Among the effects of electric current, we can list great muscle pain paralysis , burns due to the Joule Effect and even cardiac arrest. One of the most lethal shocks is the one we take in the left arm , as it is in the same path as the heart muscles.

2nd) Why don’t birds get shocks from electrical wires?

You’ve probably seen some pigeons sitting on pole wires and wondered why these birds don’t get “shocked”. The answer to this question is simple: each of the wires on the poles has an electric potential value . When the bird lands on the wire, it is under the same potential as the wire . For this bird to suffer an electric shock, there would need to be a potential difference between its legs. As there is no such difference , there is no formation of electric current through your body.

3rd) Why do we sometimes get shocks from other people?

Human skin is found at the top of the triboelectric series . This means that it has a very high tendency to lose electrons when rubbed against other materials. When we move, our skin rubs against our clothes and even the air. This friction removes electrons from the skin and it acquires a positive charge . When we touch someone, these charges tend to be transferred through contact electrification and what we feel is the effect of electrons passing from one body to another.

The human body works through electrical impulses . From the chemical signals emitted by cells to muscle contractions are controlled by small electrical currents. The electricity used by our body is produced at the cellular level through a difference in the concentration of positive and negative electrolytes : sodium and potassium , present inside and outside cells in their ionic forms . The difference in concentration of positive and negative ions produces an electrical current known as a sodium-potassium pump .

5) Visualizing the electrical wiring

During a trip, you must have noticed those orange or red balls hanging from the high voltage wires and wondered why they were there. Its function is aerial signaling , mainly because the distribution of electricity at high voltages is carried out in rural areas and accidents involving small planes used to apply pesticides on plantations can occur.