Is the coil in a car's ignition system functioning as a transformer?

AI Thread Summary
The discussion clarifies that the coil in a car's ignition system functions similarly to a transformer by increasing voltage to provide a hotter spark for the spark plugs. It emphasizes that while the voltage is increased, the total energy remains constant, leading to fewer electrons flowing per second on the secondary side compared to the primary side. The relationship between power, voltage, and current is highlighted with the formula P=U*I, indicating that energy conservation is key. The conversation also addresses misconceptions about the coil drawing more current from the battery, affirming that the coil does not increase the total energy but changes its form. Overall, the coil's role is to transform energy rather than increase the flow of electrons.
cragar
Messages
2,546
Reaction score
3
like in a car when electrons flow through the battery to the coil , the coil is like a transformer using coiled copper wire to up the voltage to give the spark plugs a hotter spark. I am not sure where this energy is coming from , so are we actually getting more electrons to flow per second and after it goes through the coil . does the coil allow it to draw more current from the battery.
 
Physics news on Phys.org
Basically, all that matters is that total energy is conserved so energy per secons is :

P=U*I so P is a constant in a transformer ( at least consider it so)

If so then IF p=5W there are an infinity of possibilities for U and I. Like U=5 I =1 or I=5 U=1 etc.

That is what happens in a transformer, energy is the same it is just expressed differently.

For different ways transformers can be made consult wikipedia.

I"ve made the exemple in direct current for easy understanding :P
 
cragar said:
I am not sure where this energy is coming from , so are we actually getting more electrons to flow per second and after it goes through the coil . does the coil allow it to draw more current from the battery.
You have the wrong idea about what a transformer does: A transformer keeps the energy constant while increasing the voltage, which means fewer electrons per second going through the secondary side than the primary side.
 
i see thanks for your answers
 
This is from Griffiths' Electrodynamics, 3rd edition, page 352. I am trying to calculate the divergence of the Maxwell stress tensor. The tensor is given as ##T_{ij} =\epsilon_0 (E_iE_j-\frac 1 2 \delta_{ij} E^2)+\frac 1 {\mu_0}(B_iB_j-\frac 1 2 \delta_{ij} B^2)##. To make things easier, I just want to focus on the part with the electrical field, i.e. I want to find the divergence of ##E_{ij}=E_iE_j-\frac 1 2 \delta_{ij}E^2##. In matrix form, this tensor should look like this...
Thread 'Applying the Gauss (1835) formula for force between 2 parallel DC currents'
Please can anyone either:- (1) point me to a derivation of the perpendicular force (Fy) between two very long parallel wires carrying steady currents utilising the formula of Gauss for the force F along the line r between 2 charges? Or alternatively (2) point out where I have gone wrong in my method? I am having problems with calculating the direction and magnitude of the force as expected from modern (Biot-Savart-Maxwell-Lorentz) formula. Here is my method and results so far:- This...

Similar threads

Replies
6
Views
2K
Replies
16
Views
4K
Replies
2
Views
1K
Replies
17
Views
2K
Replies
12
Views
2K
Replies
2
Views
1K
Back
Top