# Tag Info

43

Electricity isn't a gas that expands out to shock anything in contact with it. Electricity is a flow from high voltage to low voltage. Touching a charged object is only dangerous if you become a current path--if it uses you to get somewhere. Even if the earth had a net charge, you aren't providing it anywhere to go, so you will not be shocked. It's somewhat ...

20

I'll answer the concrete question, because it's one of those fun ones where the units are all wrong and the scales are just absurd. Does this also mean that if I release a million amperes of current into the earth, every living entity walking barefooted should immediately die? It depends on how long you do it and with how much power. And ...

9

Firstly we are not the best conductors, so current might be having a relatively hard time getting through us. But I believe the real reason is that you also need a high potential difference in order to get current flowing through you. Like lightning which needs a huge potential difference between the clouds and earth (so big that most of times a neutral ...

3

A counterpoint to Schwern's answer (which was instructive, but I believe wrong on some key points - but I will borrow a couple of numbers from it). I think the correct way to pose the question is: If a 300 mA current for 100 ms will kill a human, what should be the rate of change of the electric field around the body to induce that current? Treating ...

2

Note that a current carrying wire produces a circular magnetic field that's why it doesn't matter how you hold your hand ie how you rotate your hand around your arm as long as your thumb shows the direction of the current. Edit after comments: See the illustration I've added below. Now use your hand in the way that you've learned and convince yourself ...

2

Is there a fallacy in this statement? At least two. First, unless one is referring to a perfect (ideal, etc.) conductor, only in the electrostatic case does the electric field inside a conductor vanish. Second, in the case of an ideal conductor, there can be a steady current through without an electric field inside. Recall that an electric field ...

2

Ok so I first have taken the diagram from the wikipedia page for reference and put it here. Now if you are happy with the idea of how the potential divider works... .... then I hope that you can see that $R_1$ and $R_2$ in the Wheatstone Bridge diagram form a potential divider and there is another potential divider with $R_3$ and $R_x$ - and the points ...

1

That definition of a vector quantity is a little too simple. It needs to not only have direction, but the directions need to add depending on the angles between them in a specific way to give an overall equivalent quantity. Current in a circuit isn't really a vector quantity, it has direction but that is equivalent to just the sign of the current. You can ...

1

The energy in a typical static charge from walking across a carpet is too low to kill a human. It may be a few milliJoules. The energy available is approximately Voltage x Charge. The current that passes through your body depends on that voltage divided by the effective resistance of your body (including any clothing, shoes and other material in the ...

1

There is a concept of "voltage of a step"* in energy industry - if a high voltage power line is leaking into the ground and isn't shut down, then near that point the ground voltage difference over a single human step (when one feet is closer than the other) can be enough to kill a person; that's why it may be dangerous to approach fallen wires after a storm ...

1

Trying to address this misconception: I start of with a resistance of 1 ohm by the wire and 6 amperes which result in 6 volts. When I meet the resistor however the resistance increases to let's say 3. Does the current decrease at the same rate the resistance increases? So if the resistance goes down to 3 will the current be 2 so that in the end I have a ...

1

Maxwell's equation tells us that for the general case $$\vec{\nabla} \times \vec{E} = -\frac{\partial \vec{B}}{\partial t}$$ This vanishes not only when charges are stationary, but also when they are moving in a uniform continuous manner such as to produce a constant magnetic field (which describes your example). Another general case is when the charges ...

1

The idea in the comments above is a good one. The reason you don't need to worry about the order is that you're looking for an equilibrium solution. In terms of going on forever, it's broadly true. I mean electro magnetic radiation is exactly the kind of effect you're talking about. In a circuit there is normally a dissipative term, but in a steady state ...

1

The minus sign is wrong.The reason for this is the x which you have chosen to be positive but is in fact negative. x points positively to the right and negatively to the left,and the horizontal vector that you are using in your picture is opposite to the direction of x.So,its x=-acotθ. Cheers!

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