Magnetic Field Flashcards
What is magnetic field
Field of force created by moving current or permanent magnets
When does a current carrying wire experience a force
When the current passing through it is perpendicular to the magnetic field lines
What is the strength of a magnetic field known as
Magnetic flux density
Equation of force on current carrying wire
F=BILsinx
What does the thumb, index and middle finger represent in the lemmings left hand rule
Thumb) force
Index) magnetic field
Middle) current
Magnetic flux density
Force acting per unit current per unit length on a current carrying conductor placed perpendicular to the magnetic field
Define Tesla
A straight conductor carrying a current of 1A normal to a magnetic field of flux density of 1T with force per unit length of the conductor of 1 N/m
Equation of force on moving charge
F=BQVsinx
Define hall voltage
The pd is produced across an electrical conductor when an external magnetic field is applied perpendicular to the current through the conductor
Deriving Hall voltage
E=Vh/d
F=BQv
Fe=qE
Bqv=qE
E=Bv
Vh/d=Bv
Vh/d = B(I/Anq)
Vh=BI/ntq
How to measure magnetic flux density
Using hall voltage magnetic field perpendicular to metal
Circular motion and mag fiel
mv^2/r=Bqv
r=mv/bq
Velocity selection
A device consisting of perpendicular magnetic and electric fields where charged particles with a specific velocity can be filtered
Velocity selection equation
Bqv=eq
V=e/B
Magnetic field lines in a current carrying wire
Use right hand screen Rule
Thumb represents current
Factors that affect magnetic field strength
Adding a core of iron rich material
Adding more turns
If currents in opposite direction will the mag field attract
No repel
Define magnetic flux
The product of the magnetic flux density and the cross-sectional area perpendicular to the magnetic flux density
Equation of mag flux
=BA
=BAcosx
Magnetic flux linkage
Product of magnetic flux and the number of turns
Unit of magnetic flux
Webers
Unit of magnetic flux linkage
Wb turns
Equation of magnetic flux linkage
=BANcosx
Define electromagnetic induction
A process in which emfs is induced in a closed circuit due to change in magnetic flux
Faraday’s law
The magnitude of the induced emf is directly proportional to the rate of change in magnetic flux linkage
Equation of farday’s law
=N^BA/^t
Lenz’s law
The induced emf acts in such a direction to produce effects which oppose the change causing it
Equation of lenzs law
Same as Faraday but opp
