20.2.3—Magnetic flux density as the force acting per unit current per unit length
- Syllabus
- 9702–2028–2029
- Objective
- 20.2.3
- Level
- A2
Magnetic flux density is force per unit current per unit perpendicular length
For a wire perpendicular to a field, B=F/(IL), measured in tesla, so 1 T=1 N A⁻¹ m⁻¹.
The definition assumes the conductor is perpendicular; otherwise divide by IL sinθ or resolve the perpendicular component.
A 0.40 N force on a 0.20 m wire carrying 2.0 A gives B=1.0 T when perpendicular.
Tesla is not force per charge; that relates to electric field, while B describes magnetic force on current or moving charge.
ConceptA-Level CAIE Physics A2