physics - chapter 12

how do magnets attract materials?

via induction

what happens when objects are magnetized

their electrons all point in the same direction

how can magnets be damaged

dropped or heated

Earths north pole is

magnetic south

what does the thumb represent in the RHR

force

what does the pointer represent in the RHR

velocity

conditions for magnetic force?

needs charged particles and velocity perpendicular to the field

does magnetic force do work?

no, work is parallel while Fm is always perpendicular

does magnetic force change the speed of a particle?

no, but it accelerates it through direction changes

how do particles move in a magnetic field?

circularly

does kinetic energy change in a magnetic field?

no, Ek doesn’t change

how do positively charged particles move in an electric field?

in the same direction as the field

how do negatively charged particles move in an electric field

in the opposite direction

why are protons used in an MRI

they are abundant in the human body

what does a strong magnetic field do in an MRI

aligns particles

what does the RF pulse do in an MRI?

it disturbs the H+ ions and rotates them

what happens when the RF pulse is turned off?

the particles will realign with the magnetic field and release energy