Saturday, November 30, 2013
Why birds donot get an electric shock sitting on an high voltage overhead line?
First Answer-
We have often seen birds sitting on an overhead power transmission line without getting an electric shock . Electric shock is produced when some amount of current passes through the body of any living being . When a bird sits on an overhead high tension wire its body gets charged for the moment and it is at the same potential as that of the wire. Since current always chooses a low resistance path for its flow so no current flows through the body of the bird. But if the bird accidentally touches the ground with its body in contact with the wire then its gets an electric shock.We know that ground is at zero voltage potential. In this case an electrical circuit is completed through which huge current flows to the ground since a potential difference is created . So the bird will not get an electric shock as long as it remains at same potential with the high voltage wire.
Second Answer-
A shock is caused by a flow of current through a body. So for the bird to be shocked there would need to be a current running through her body. There is no current running through the bird's body for two reasons. The first reason is that the bird's body has a high resistance, so the current would rather pass through the wire instead of the bird. Since the current can go through the wire or through the bird to get to the same point, you can think of the wire as being a highway and the bird as a one way mountainous country road. It is easier for the current to pass through the highway (or wire) than it would to take the harder mountainous route (the bird). The second, and more important, reason no current passes through the bird is that in order for current to flow through the bird there must be a voltage across the bird's body. Since, the bird is careful to have both feet on the same wire there is not enough voltage across the bird's body to allow current to flow. If the bird were to touch the wire and at the same time the ground or some object connected to the ground, it would receive a deadly shock. Power lines are extremely dangerous and should always be avoided. Touching a power line is strictly 'for the birds'.
We have often seen birds sitting on an overhead power transmission line without getting an electric shock . Electric shock is produced when some amount of current passes through the body of any living being . When a bird sits on an overhead high tension wire its body gets charged for the moment and it is at the same potential as that of the wire. Since current always chooses a low resistance path for its flow so no current flows through the body of the bird. But if the bird accidentally touches the ground with its body in contact with the wire then its gets an electric shock.We know that ground is at zero voltage potential. In this case an electrical circuit is completed through which huge current flows to the ground since a potential difference is created . So the bird will not get an electric shock as long as it remains at same potential with the high voltage wire.
Second Answer-
A shock is caused by a flow of current through a body. So for the bird to be shocked there would need to be a current running through her body. There is no current running through the bird's body for two reasons. The first reason is that the bird's body has a high resistance, so the current would rather pass through the wire instead of the bird. Since the current can go through the wire or through the bird to get to the same point, you can think of the wire as being a highway and the bird as a one way mountainous country road. It is easier for the current to pass through the highway (or wire) than it would to take the harder mountainous route (the bird). The second, and more important, reason no current passes through the bird is that in order for current to flow through the bird there must be a voltage across the bird's body. Since, the bird is careful to have both feet on the same wire there is not enough voltage across the bird's body to allow current to flow. If the bird were to touch the wire and at the same time the ground or some object connected to the ground, it would receive a deadly shock. Power lines are extremely dangerous and should always be avoided. Touching a power line is strictly 'for the birds'.
What is skin effect?
Answer for interview - When DC current is passing through a conductor, then the distribution of current throughout the entire conductor is uniform. But in case of AC current, the distribution of current throughout the cross section of conductor is not uniform. Here, current density is higher at the surface area as compared to the center of the conductor. When the frequency of current get increased then this phenomen become more prominant. This phenomen of non-uniform current distribution under AC is termed as skin effect.
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