- The
**Magnetic Flux Density**of a magnetic field is defined as the force**F**acting per unit current**I**in wire of unit length**l**at right angles to the feild**B**.

ü ** F=BIl** (Your new
friend "Bill"!)

- The direction of the
Current, Field and Movement correspond to the se
**C**ond finger,**F**irst finger and thu**M**b of one's left hand: Fleming's Left Hand Rule. - Magnetic flux density,
instead of being "Newtons per Amp-metre", has its own units, the
**Tesla (T)**. - When the movement is
not perpendicular to the field, one must resolve the perpendicular
component of the field.
- If the angle,
**q**, is the angle between the direction of the field and that of the horizontal component of the field, then the magnitudes of the horizontal and vertical components are*B cos***q**and*B sin***q**, consecutively. The equation therefore normally becomes

ü *F=B Il cos ***q**

- For a rectangular coil
with a central point of pivot in a magnetic field, the force experienced
would also be affected by the number of turns
**n**, and distance between the two sides of the coil that run perpendicular to the field**d**. This makes our equation (the one you'll have to learn to love!)*F = B I**l**d n cos***q**, which, quite frankly, looks horrible. If you're sharp, you will have noticed that d * n is equal to**A**the area of the coil, so remember:

ü
*F = B I A n cos ***q** (Your new __very good
friend__ "Bianka" if you imagine the q as an "a"!

| Back | Revision
Index | Next |

| Physics Home |

Copyright © Simon van Leishout 2000

(HTML Author)