A small doubt in transformer

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A small doubt in transformer....

Hi friends

A transformer (say step up one) increases the output voltage. However, power input is equal to power output so output current should be small. Now yesterday I took a spark circuit(from an electric gas lighter using a 3 volt battery) and allowed the current from output of the transformer coil or say ignition coil to conduct through my body and I felt some shock. What was that? Wasn't that electric current that made me feel shock. But as I said output current must have been very small. Output voltage was high and if that made me feel shock then what is electric current?
I hope you got what I am confused in. Can someone explain?
 

Answers and Replies

  • #2
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You need a fairly high voltage to overcome the body's resistance in order to feel a shock. So what you felt was a tiny current (and you're lucky it was tiny at the time...) being "pushed" by a high voltage.

In an ideal world the power in and out of a transformer should be the same (but there are losses in the real world, so out is always less than in). Power is voltage times current, so a low voltage at a high current has the same power as a high voltage at a low current.
 
  • #3
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What schip666 said, but I'd like to add the following:

Your idea is vague in that you don't know what the minimum current is for you to feel a shock. Therefore, to say you shouldn't have felt a shock because the current is 'tiny' just doesn't make sense.
 
  • #4
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You need a fairly high voltage to overcome the body's resistance in order to feel a shock. So what you felt was a tiny current (and you're lucky it was tiny at the time...) being "pushed" by a high voltage.
Thats what I am talking about. Since the current was tiny, why did I felt shock.
Your idea is vague in that you don't know what the minimum current is for you to feel a shock. Therefore, to say you shouldn't have felt a shock because the current is 'tiny' just doesn't make sense.
What current would a 3 volt battery would give you to feel a shock? Futher I use a transformer which increases output voltage for same resistance and decreases the current further. So why did I feel the shock?
 
  • #5
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For same resistance current is proportional to voltage applied. According to this statement, more the voltage drop more should be the current. But transformer decreases the current while increasing voltage....so what is wrong here?
 
  • #6
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Thats what I am talking about. Since the current was tiny, why did I felt shock.

What current would a 3 volt battery would give you to feel a shock? Futher I use a transformer which increases output voltage for same resistance and decreases the current further. So why did I feel the shock?

The voltage is irrelevant when it comes to a shock. The human body can only feel the shock above a certain current.

As long as the system provides a current that is greater than that value you will feel it.

In your case, the battery delivered a current that was above your minimum requirement to feel it, therefore you felt the shock.
 
  • #7
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You should feel a larger shock at the time the battery is disconnected. In fact, this may have been the cause of the shock you felt if you were not too careful connecting the primary side to the battery, but had intermittent connections and disconnections in the process.

Power_in = power_out is a little bit vague. Neglecting losses and magnetization current, energy_in integrated over time is the energy_out integrated over time. Energy is also stored in the core of the transformer in the form of magnetic flux.
 
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