Explain why V1 and V2 do not add up to Vs.

[05gmccarthyg]

Could someone please help with with an answer to that question? I'm stuck on it.

If you require some more details, please ask.

Thanks.

 

[telectrix]

only thing i can suggest is that the choke, or ballast, is there to supply the lamp with whatever the lamp needs to light. there is no reason for the 2 voltages to add up to the supply voltage.

 

[05gmccarthyg]

That is the circuit diagram we are given. Hopefully that will help.

Thanks.

 

[buttonmoon]

I think that the reason v1 and v2 don't add up to vs as per kirchoff's law is that this is a LRC circuit containing both inductive and capacitive elements which are putting the 2 voltages out of phase with each other. I think you need to use a phasor diagram or trigonometry to solve this.

 

[dichroic]

In laymans terms.... the power being used by the choke (inductive part of the circuit Xl) is out of phase with the power being used by the tube (resistive part of the circuit Xr) so the two added together will not equal the supply voltage Vs.
Have a look at a standard 3,4,5 triangle model to get the idea.

Hope this helps.