5. Magnetism Flashcards
What happens if you split a magnet?
new north and south pole
How do electric charges move in electric field vs How do they move in magnetic field?
From pos to neg vs Nowhere! Electric charges don’t cause magnetic fields, but moving charges do and they move in closed loops
Right hand rule to find direction of magnetic field from a current
Thumb = current, curl fingers = direction of mag field
X’s vs dots
pointing into page vs pointing out of page
Is force parallel or perpendicular to current and mag field?
perpendicular to both
Formula to find magnetic force on a moving charge
F = qvBsin(theta) q = charge, v = vel of charged particle, B = mag field
Theta may be 90 degrees since they’re all perpendicular to e/o
What is Q of p+ and e-? Neutrons?
1.6E-19 C for p+, take the neg for e-
Neutrons = 0 C
Right hand rule to find direction of magnetic force on a moving charge in mag field
Thumb = direction of vel
Fingers = direction of mag field
Palm = direction of force for pos charge
Back of hand = direction of force for neg charge
If force has to be perpendicular to both current and mag field, current has to be perpendicular to mag field. What happens if current isn’t perpend to mag field?
Force = 0
Formula to find magnetic force w/o moving charge but instead w/ a current-carrying wire
F = ILBsin(theta)
I=current
L=length of wire
B=mag field
Theta may be 90 degrees since they’re all perpendicular to e/o
What happens if you put 2 currents next to each other going in the same direction vs going in opposite direction?
Forces go in each other —> 2 currents attract e/o vs forces go away from each other —> 2 currents repel e/o
What happens if you move a wire thru a mag field?
You get a current in the wire
What’s magnetic flux? What happens if there’s a change in magnetic flux? What happens if mag field inc/dec in loop?
How much a mag field moved thru a given area. Change in this gives you induced current
Inc thru loop —> current goes clockwise
Dec thru loop —> current goes counterclockwise
Paramagnetic vs diamagnetic vs ferromagnetic
Magnetic field will cause parallel spins in unpaired e- —> weak attraction (ex: gold, aluminum, copper) vs material that only has paired e- and has no net magnetic field —> repelled by magnetic field (ex: wood, plastic, glass) vs have unpaired e- and magnetic dipoles oriented randomly —> no net magnetic dipole, BUT is still strongly attracted to a magnetic field (ex: iron, nickel and cobalt)
Formula to find magnetic field from a linear vs circular loop
B = (mu_0I)/(2pir) vs B = (mu_0I)/(2*r)
mu_0=permeability of free space, 4piE-7
I=current
