Closing of switch in series circuit

AI Thread Summary
In a series circuit, closing the switch causes the ammeter needle to jump to its full value instantly due to the high differential potential across the circuit. Current is conventionally defined as the flow of positive charge, even though it was discovered before the electron theory, leading to confusion about the direction of current flow. While electrons flow from the negative terminal to the positive, the established convention describes current as moving from positive to negative. The instantaneous response of the ammeter is explained by the electrostatic repulsion of electrons, where the movement of one electron prompts the movement of others along the wire. This demonstrates that the net flow of charge occurs much faster than the individual movement of electrons.
mich_v87
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If an ammeter is connected to the negative terminal of a battery,so it is on the opposite end of the line from where the current leaves the battery and enters the circuit,right?So Why, in a series circuit, the meter needle jumps to it's full value instantaneously with the closing of the switch ?

is this answer right : because of the high value of the differential potential ?
 
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If an ammeter is connected to the negative terminal of a battery,so it is on the opposite end of the line from where the current leaves the battery and enters the circuit,right?

This always confuses me. Doesnt current leave from the negative side and enter the positive. Since current = flow of electron, and electrons = negative. Wouldnt it make sense to say the current flows from the negative side?
 
Current was discovered long before electrons. Electron flow explains current, but current had already been defined as the rate of change of net positive charge. So it is a matter of hard-to-overturn convention. (Just think - protons could have been defined as negative and electrons positive!)

Otherwise, the OP's question is a rewording of the old: "why does the light come on as soon as I press the switch?" The flow of current is not equal to the flow of individual particles within it, since the movement of an electron at one end of a wire will cause the next electron to start moving (by electrostatic repulsion), and the next, and the next, all the way to the other end of the wire. As a result, the net flow of charge is a lot greater than individual electron velocities which are, by comparison, snail-paced.
 
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