Question

2.

(a) The drift speed of electrons in a complete circuit, is typically a few mil- limeters per second. Yet, a lamp 3.0m away from a light switch turns on instantaneously when you flip the switch. Explain this apparent paradox.

(b) To move charges in metallic wires, an internal electric field must exist in the wire. In such a wire, are the electric field and the electric current in the same or opposite directions? Explain.

Answer 1

2. a) because of collision , the charge carriers ( electrons ) are drifting with very small speed in the circuit. But, When a voltage is applied , electrified is set up with a speed of light and it exerts electric force on all free electrons in the circuit and this make all the electrons to move with very large acceleration and thus the electron are drifting at once. So ,although drift velocity is so small ,lights turned on soon after the switch flip

b) only when a potential difference is applied across a circuit, an electric field is set up inside the conductor from higher potential to lowar potential. Due to this electric field, electrons are experienced an electric force ,such that electrons move opposite of electric field (That is toward positive end of circuit that is higher potential region)

In short, current flows opposite of electron or in the same direction of inside electric field.