Mistake Master
Mistake Master · AP Physics 2 · Unit 12 · Step-Through Animation
The Field Goes Around, Not Outward
You'll learnthat a wire's magnetic field circles it rather than radiating from it, that it fades as one over the distance and not as an inverse square, that two currents running the same way attract, and that only the length of wire inside a field belongs in the force.
A current-carrying wire makes a magnetic field, and almost every wrong answer about it comes from drawing that field like an electric one. It does not point away from the wire, it does not die off as an inverse square, and two matching currents do not repel. Eleven short steps; press Next for each one.
it circles the wire · one over r, not r squared · same way attracts
Before you start
What you're looking at
A long straight wire carrying a steady current, and later a second wire beside it.
The question
What shape is the field a current makes, how fast does it fade, and what do two currents do to each other?
Step 1 / 11