How does a resistor weaken the electric field in a wire?

Question

Some students that I mentor are building a solar powered cell phone charger. I want to do a few lessons about electricity so that they understand the physics in their charger, but I don't have a very good intuitive understanding of electricity.

I am trying to imagine what happens (at an atomic level) when power is lost from an electric circuit. Suppose I hook a battery up to a resistor. The resistor "resists" the flow of electrons through the wire and generates heat.

I can measure the voltage drop across the resistor at a given current. As I understand it, voltage is just a measure of electric field strength (the electric field in the wire), so a voltage drop is a weakening of the electric field in the wire... the field in the wire after the resistor is weaker than the field in the wire before the resistor.

I don't really get how the resistor works, or how it weakens an electric field. Does anyone know a good explanation?

Answer 1

1) electric field in a wire only depends on length and voltage of battery connected to wire, and is given by E = V/L



2) because of this electric field electrons/holes/or some other charged particles come in motion as they experience force coz of electric field.(f = E*q}



3) after travelling some distance the electron get collided in it's path with atom/hole and loses it's KE which get converted into heat and this process give resistance



4) different material have different resistance coz of different concentration of free electrons/inner structure etc



Summary:

If you have a wire(any material) of length L and connect it with battery electric field in it would be E= V/L

Current I = V/R = E*L/R

Answer 2

what happens when current flow through a conductor. the electrons are on their way to the ground and they do so at tremendous speed. now note that electrons is just one of many particles in an atom so when the electrons is on its way it collides when all sorts of atoms on the way and this happens millions of times per second. this collision and friction with other atoms is what causes heat. think of this as a pissed off man who is late for work. once he gets on the road, he is racing and crashing into different stationary cars. so yes the friction and collision between electrons and atom causes heat. after all an electron has mass so it has momentum and it can induce movement when it collides with other atoms and this sorts of wastes energy as colliding with a car on the road will impede a drivers speed as well as waste his time. that's why resistance is called impedance and is wasteful in circuits. once this movement, collision and friction starts occuring.



SIMPLY PUT A RESISTOR IS AN IMPEDER. THE PERFECT ANALOGY IS A SPEED BUMP ON A ROAD. IT IS MEANT TO SLOW DOWN THE RATE OF ELECTRON FLOW. THINK OF ELECTRONS AS TRAFFIC MILLIONS OF CARS MOVING ON A ROAD. NOW SOME PLACES LIKE IN NEIGHBORHOODS WITH KIDS. U WANT MORE SPEED BUMPS AND SPEED SIGNS TO SLOW DOWN TRAFFIC FOR THAT SPECIFIC PURPOSE. THAT IS EXACTLY WHAT A RESISTOR DOES. ITS NAME SPEAKS FOR ITSELF - RESISTOR OR BETTER YET AN IMPEDER

Answer 3

The resistor limits current in the circuit according to ohms law I = E / R.

However the current is same before resistor as after resistor (every where the same) so electric field is same also.