# Changing electric flux caused by a resistor

1. Feb 11, 2012

### TheLil'Turkey

I'm learning the basics about electromagnetism, including that a changing electric flux through an open surface causes a magnetic field. Obviously a capacitor causes this, but doesn't a resistor like a light bulb (whose resistance varies with temperature and therefore time) also cause this?

2. Feb 11, 2012

### Antiphon

Yes. Part of the magnetic field around the resistor comes from the current that flows through it. Another part comes from the time-changing electric field that spans it. You would model this as a capacitor in parallel with the resistor.

3. Feb 11, 2012

### TheLil'Turkey

That makes sense. Thanks. I assume that the resistance of ALL resistors increases with increasing temperature. Is there a crude, classical physics model to understand why this is so?

4. Feb 11, 2012

### TheLil'Turkey

I'm going to take a stab at answering my own question from post 3. I think that as the temperature goes up, the average distance an electron in a resistor travels before changing direction decreases because the atoms in the resistor are jiggling faster. Is that right?