A2 Physics Magnetic Fields

draw a magnetic field line

they travel from a north pole to a south pole

What happens if there is an external magnetic field acting on a current-carrying conductor

current-carrying conductor produces its own magnetic field

when external magnetic field acting on it, it experiences a force

formula for force on a current-carrying conductor

F = BILsinθ; F is force on current-carrying conductor, B is magnetic flux density of applied magnetic field, I is current, L is length of conductor, θ is angle between the conductor and magnetic field

define magnetic flux density

force acting per unit current per unit length on a wire placed at right angles to the magnetic field

unit for magnetic flux density

tesla (T)

what does it mean if there is higher flux density

the magnetic field is stronger

what does each finger refer to in Fleming’s left hand rule

thumb is force, index is direction of applied magnetic field, middle is direction of current

what happens when a moving charge interacts with an applied magnetic field

it experiences a force since the moving charge produces its own field

formula for force on a particle with charge Q

F = BQvsinθ; F is magnetic force on particle, Q is charge of particle, v is speed of particle, θ is angle between charge’s velocity and magnetic field

define hall voltage

the potential difference produced across an electrical conductor when an external magnetic field is applied perpendicular to the current through the conductor

what do each letter mean in the hall voltage formula

B = magnetic flux density
q = charge on each charge carrier
I = current
n = number density of charge carrier
t = thickness of the conductor

derive hall voltage

define magnetic flux

product of magnetic flux density and the cross-sectional area perpendicular to the direction of the magnetic field

formula for magnetic flux

Φ = BA

formula for magnetic flux linkage

NΦ = BAN

what is magnetic flux linkage

product of magnetic flux and number of turns

what is faraday’s law

induced e.m.f. is directly proportional to rate of change in magnetic flux linkage

what is lenz’s law

induced e.m.f. acts in the opposite direction of the force that caused the change in magnetic flux

difference between faraday’s and lenz’s law

faraday’s law is for magnitude of induced e.m.f. and lenz’s law is for the direction of induced e.m.f.

what is a magnetic field

a region where a force acts on a current-carrying conductor or moving charge