1. A –Level Physics: Magnetic Fields Magnetic Flux

2. Objectives:

3. FLASHBACK
FLASHBACK: Compare and contrast radial and uniform gravitational and electric fields

4. Starter Activity
In partners, discuss and brainstorm everything you currently know about MAGNETIC FIELDS

5. Magnetic Fields- An Introduction
Electric and magnetic fields are similar and intertwined byt where electric fields affect charges, magnetic fields affect poles. A magnetic field is defined as “a region in which a pole feels a force”
Draw the magnetic field around a simple bar magnet with two poles
When we draw a field, the file lines would show the direction that a north pole would be forced. The field lines (also known as magnetic flux lines always act N to S)
5.1 x N

6. Magnetic Flux Density ɸ = Bsinθ x A ɸ = BA A B
This box shows a region of flux (a region that contains magnetic field lines). Every magnet has a specific strength, aka magnetic flux density (B) measured in Teslas (T) A
By changing location around the magnet, you get a different value for the quantity of flux
( ɸ ) (measured in Webers). This is because the field lines get concentrated at poles B
To calculate the quantity of flux ( ɸ ) at a particular area around a magnet, you multiply the area by the component of flux density perpendicular to the area.
ɸ = Bsinθ x A
If the area is already perpendicular then…
ɸ = BA

7. Magnetic Flux Density B= ɸ A A
In the same vein, to determine the magnetic flux density, you simply need to find how the flux is shared over a specific area (a.k.a. how packed the flux is) A
B= ɸ A

8. Magnetic Flux Density
If the bar magnet has a flux density of 20mT perpendicular to the area in orange. How much flux would be contained if this area was 10cm2
In this position, the field is now at 75° to the area. How much flux does it now contain?
1) 10cm2 = 10 x 10-4, then X 20x10-3 = 2.0x10-5 Wb. 2) Same but with Sin75 = 1.93x10-5 Wb

9. Complete the questions provided
Practice and I/S
Complete the questions provided
Pg 65 of blue text book