Introduction to the Module Flashcards
What is an Electromagnetic Force?
A force is produced on a current carrying conductor when subjected to an externally-established magnetic field
What is an Induced Electromotive Force?
An emf is induced in a conductor moving in a magnetic field
What is the value of Lorentz Force?
F = Bil
F = Force
B = Magnetic Field
i = Current
l = Length of wire
What is the right-hand rule and what does it do?
The right-hand rule gives the direction of the magnetic field around a current carrying wire. Point your thumb in the direction of current flow, and then close your fingers into a fist with the thumb still pointing. The way that the fingers close indicate if the field acts clockwise or anti-clockwise
What is the equation relating the magnetic intensity from a current carrying wire and the current carried by the wire?
H = i / (2 * pi * r)
r is the distance between the point of intensity you are measuring and the centre of the current carrying wire
What is the equation relating the Magnetic Flux Density and the Magnetic Intensity from a wire?
B = Mew0 * Mewr * H
- B is the Magnetic Flux Density
- H is the Magnetic Intensity
- Mew0 is the Permiability of air
- Mewr is the Relative Permiability of the material you are travelling through (If you are still travelling through air, then this value equals 1)
Can the relative permeability of a material vary?
Yes
What is a Hysteresis Loop?
It demonstrates the relationship between the Flux Density B (y-axis) and the Magnetic Intensity H (x-axis)
A path that a system will follow
What is the name for the average curve within a Hysteresis Loop?
A Magnetisation Characteristic
If a current carrying wire is represented by a dot, what does that mean?
Current is flowing out of the page
If a current carrying wire is represented by a cross, what does that mean?
Current is flowing into the page
For a magnetic circuit with a gap, how do we determine the current required for a given flux density Bg
We need to integrate the magnetic intensity in each material with the length that the material composes over the circuit
How do motors transfer energy?
They transfer electrical energy into mechanical energy
How do generators transfer energy?
They transfer mechanical energy into electrical energy
Why would we put a gap in a ring with an electrical current and magnetic field?
We need the gap to allow movement to occur within. Without the gap, the components of our machines won’t operate
