Magnetic Fields and the Motor Effect
This page covers the fundamentals of magnetic fields and introduces the motor effect in magnetic fields.
Magnetic fields, also known as B-fields, exert forces on magnetized materials. The density of field lines represents the strength of the field, with field lines never intersecting.
Highlight: Magnetic field lines always point from North to South.
When a wire carries an electric current, it induces a magnetic field perpendicular to it. The direction of this field depends on the current flow and can be determined using the right hand grip rule.
Example: To use the right hand grip rule, point your thumb in the direction of the current flow. Your curled fingers will then indicate the direction of the magnetic field lines around the wire.
The motor effect occurs when a current-carrying wire is placed in a magnetic field. The interaction between the wire's induced field and the external field creates an area of high-density field lines, resulting in a force on the wire.
Definition: The motor effect is the phenomenon where a current-carrying conductor experiences a force when placed in a magnetic field.
The force on the wire can be calculated using the formula:
F = BIL sin θ
Where:
- F is the force on the wire inNewtons
- B is the magnetic field strength inTesla
- I is the current in the wire inAmperes
- L is the length of wire in the magnetic field inmeters
- θ is the angle between the wire and the magnetic field
Vocabulary: Tesla T is the unit of magnetic flux density or magnetic field strength.
For charged particles moving through a magnetic field, a similar formula applies:
F = Bqv sin θ
Where q is the charge of the particle and v is its velocity.
The page also introduces the Hall effect, which occurs when a current flows through a conductor in a magnetic field. This effect causes a voltage difference across the conductor, known as the Hall voltage.
Highlight: The Hall effect is used in Hall probes to measure magnetic field strength.
