Your physics text book should have the answers. Classical physics text books are typically very nicely written, so you can give that a shot if you want.
You may also want to look to equations the book may give you.
So I'll explain 3 and 6 as an example:
The equation for magnetic field strength is B = NIμ/L
N is number of turns, I is current, μ is magnetic permittivity, and L is length. If we were to hold current, permittivity and Current constant, we can show that increasing N, the number of turns, would increase the magnetic field strength.
We need to show the force due to an electromagnet depends on magnetic field strength, current in the wire, and the length of wire in the magnetic field.
The equation for force is F = BČA/(2μ₀)
All the variables are as they were in question 3.
So because magnetic field strength B influences electromagnetic force, and the current and length of wire influence field strength, the statement that electromagnetic force depends on magnetic field strength, current in the wire, and the length of wire in the magnetic field is true.
And just for fun, I'll do the short answers with short and, perhaps, inadequate explanations.
Yes, if a magnet is broken in half, it will become two magnets with 2 sets of north and south poles.
Magnetic forces are dependent on distance, much like gravitational forces.
Field lines flow from north to south in a sort of arc. They do not break inside the magnet, but travel out through the north pole again. (Images does it better justice, so you should google it.)
Depending on the direction of current flow, the needle would either point towards or away from the wire. (Right hand rule.)
A motor transforms electric energy into kinetic energy. Galvanometers measure charge flow through a circuit. (Better question might have been how they're similar)
Sea floor rocks can show the history of the earth's magnetic field. (Different directions of magnetization)
Human history is the story of complaisance. While disaster is fresh in our memory, we take precautions. But as the memory of disaster recedes, we start to take risks.
Last edited by SilentSaber; 03-26-2010 at 05:43 PM.