Question

If the strength of the magnetic field at A is 27 units and the strength of the magnetic field at B is 3 units, what is the distance to B?



10 m

225 m

15 m

Answer 1

https://clackamasweb.owschools.com/media/g_ipc_2014/9/magnetic_field_ex2.gif

Answer 2

@dtan5457

Answer 3

15 m?

Answer 4

How'd you get 15?

Answer 5

15 is right but you need to know why also.

Hint: look at the coulomb's law equation. See that distance in the denominator is squared? What does that mean?

Extra: There are also other instances in physics where the distance in the formula is squared, and those are generally, collectively called the inverse square law.

Answer 6

alias, you're thinking of electric fields emanating from point charges, which is expressed by coulomb's equation. The relationship (inverse square law) would be the same if we were taking about magnetic fields from monopoles (like an electron).

For magnetic fields from wires carrying currents the relationship is \(\dfrac{1}{r}\) and from dipole (i.e. permanent bar magnets) it's \(\dfrac{1}{r^3}\).

It seems like were missing some info in the question, what is the reference point? "distance to B" from what?

Answer 7

seems like i need to review physics, thanks @aaronq

Answer 8

thanks