How Do You Calculate Current in a Car's Rear Window Heater Circuit?

[dan greig]

I have been given a question about heating elements in a car rear window heater. I have been given the voltage of the battery in the circuit and the resistance of each element in the circuit.

I can't find any info because i don't really know what sort of circuit this is!

How do i calculate the current in the circuit as it is and if two of the elements burn out and no longer conduct electricity?

Is this as simple as I = V/R?

 

[mukundpa]

we have to know how many resistance are there and in what way they are connected? Series or parallel ?

 

[dan greig]

there are 8 resistors in each circuit and i have a values for them. I think one circuit is in parallel and the other in series. When the failed resistors have failed do i just calculate the current as if they weren't there? if so why?

 

[berkeman]

Is this as simple as I = V/R?

Yes. Just divide the currents according to the resistances of each leg. As to what happens when the resistor fails, my guess is that car window resistive elements fail open, so then that would make their resistance go to infinity, and the current through the failed element go to zero. Depending on the construction of a resistor in general, however, they can potentially fail either open or short.