# Homework Help: Small question on Solenoids

1. May 5, 2010

### Eleventh_Hour

It's a small question, really. For solenoids, if I have a 'northern' end, what part of a bar magnet would be attracted to it? Is the Northern side actually a north pole?

Also, is KE = PE = Work = qV ~ where V is voltage / emf?

2. May 6, 2010

### ehild

Re: Solenoids

The northern end of a solenoid attracts the south end of a bar magnet.

It is the Earth, which has its south pole as a magnet at the North Magnetic Pole.

As your other question, KE =1/2 mv^2 is the kinetic energy and it is not equal to the potential energy PE. The electric potential at a point is the work done on a unit positive charge when it moves from that point to somewhere where the potential is defined zero. The potential energy of a charge q is PE=qV. The work of the electric field when the charge moves from a point at V potential to 0 potential is W = qV. The unit of potential is volt (V), that of work is joule (J).
The emf of a voltage source is the potential difference between its terminals when no load is connected.

ehild