EM induction Flashcards
1
Q
What is magnetic flux?
A
- magnetic flux density, B, is a measure of the strength of a magnetic field
- it helps us to think of it as number of field lines per unit area
- the total magnetic flux, Φ, passing through an area, A, perpendicular to a magnetic field, B, is defined as:
- Φ = BA
- measured in Wb
- thought of as toptal number of field lines
2
Q
What happens if there is relative motion between a conducting rod and a magnetic field?
A
- if there is relative motion between a conducting rod and a magnetic field, theelectrons in the rod will experience a force, which causes them to accumulate at one end of the rod
- this induces an electromotive force across the end of the rod
- this is called EM induction
3
Q
How can an emf being induced in a flat coil or solenoid?
A
-
moving the coil
- towards or away from the poles of a magnet
-
moving a magnet
- towards or awy from the cvoil
4
Q
In either case, what causes the emf?
A
- causes by the magnetic flux that passes through the coil changing
5
Q
What happens if the coil is part of complete circuit?
A
- an induced current will flow through it
6
Q
What does the size of the emf induced depend on when moving a coil in a magnetic field>
A
- magnetic flux passing through coil, Φ
- number of turns in the coil that cut the flux, N
7
Q
What is flux linkage?
A
- the product of the number of turns and the magnetic flux passing through the coil
- NΦ = BAN
- for a coil perpendicular to the field
8
Q
What does the rate of change in flux linkage show?
A
- rate of change of flux linkage tells you how strong the elctromotive force will be in volts
- a change in flux linkage of one weber per second will induce an electromotive force of 1 volt in a loop of wire
9
Q
what do you do if the magnetic flux isn’t perpendicular to the area?
A
- need to use trig to resolve the magnetic field vector into components that are parallel and perpendicular to the area
- Φ BAN cosθ
- where θ is the angle between the field and the normal to the plane of the loop
