Why does not it blow the birds on the wires: biology and physics in action

Probably, every person sometimes wondered why he did not stream the birds on the wires, seeing a whole flock that had settled on a dangerous "roost". Of course, those who remember physics well for the eighth class can easily explain this phenomenon. But for most people this knowledge turned out to be unclaimed in life, therefore they were safely forgotten. Let's try to restore them.

"Personal Protection"

There are several factors explaining why it does not hit the birds with wires. First, let's look at the biological, although they are less significant. Firstly, on the feet of the flyers there is a layer of horny scales. To some extent they act as insulators, although they are rather weak. Secondly, birds are able to sense the strength of the electromagnetic field. If the power line conducts a voltage of 500 kV, the birds simply avoid sitting on it.

Curiously, birds prefer to use insulated wires when landing. It's hard to say whether this is another reason why it does not hit the birds with wires on the wires: perhaps it's just nicer and easier for them to fix the paws on the insulation. Although some scientists have the opinion that this also triggers the protective sensitivity of flyers.

Why does not an electrician get a shock when they sit on the wires: the rationale from the point of view of physics

The physical explanation of the phenomenon is much more significant. To begin with, in order for the bird to "jerk" the current, it must pass through the bird's body. And this requires the presence of a significant potential difference between any two points. In this case, between the legs of the flyer. However, it sits on one wire, the voltage in which does not change all the way. Accordingly, the differences are not observed. At the same time, if we consider a bird as a branch of an electrical circuit, its resistance is much greater than the resistance of the wire itself. So the current goes along the site, where its "path" is facilitated.

It is somewhat differently explained why it does not hit the birds on wires with very high voltages. Through them there is not a direct current, but an alternating current. In this case, the feathered body becomes, you might say, a condenser: it first accumulates a charge, and then discharges. Since the body of the bird is small, its capacity is also meager, and the current passing through the fly is not dangerous. The larger the linear dimensions of the object and its volume, the greater its capacity becomes. So, for example, if a stork sits on a high-voltage wire , then such a landing will not end well for him.

When all the same "pull" the current

Note that birds still sometimes die using wires as a perch. This happens when a third point (most often the wing) comes into contact with another wire or a pole that supports the line. In both cases, a potential difference occurs, and current flows through the body of the bird. Most often this happens with relatively large birds like crows, whose wingspan can be greater than the distance between the wires.

Be careful with the experiments!

Knowing well why birds do not hit the wires with wires, it's easy to come to the conclusion that a person can hang on them, clinging to both hands (if it's not about the lines of the power line). Theoretically, this is true. However, it must be remembered that the slightest touch by the third point to any object that can serve as a conductor, will kill the experimenter. Birds can easily avoid such a touch: they sit down on the wires from above. Someone must throw you into the air, breaking the contact with your body in time. Such a trick is possible only for circus performers. Therefore, when dealing with any components of the electric chain, it is better to follow scrupulously the prescribed rules of personal safety.