# Closing of switch in series circuit

1. Oct 18, 2005

### mich_v87

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 ?

2. Oct 18, 2005

### ranger

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?

3. Oct 18, 2005

### El Hombre Invisible

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.