o Course homepage, Ongoing Lectures, TT-system 

• Instructor’s weekly informal sessions:

Tu 3:30-4:20, RAS 213 ; Fri 4-5, RLM 5.104

Lecture: 19

Magnetic force

• Exercise on the cross product: RHR#2
• The cross product given in a matrix form of Cartesian components.

Ampere’s law:

• Long wire problem (revisit)
• A current sheet: HW7: Q10

Biot-Savart law

• B at the center due to a circular arc, which as I, R and its angle q
• B at the center of a current loop: RHR#3
• Digression on amperian loops

· HW7: Q16, Long solenoid (text Fig 29.28-31)

· HW7: Q14, Toroid (text Fig 29.33)

• B due to a line-segment wire. Given: I, a, limits of angles: q₁ and q₂.

· Direction of B

· Magnitude of B: General formula

· Long wire limit

· Current-configurations (with various geometries): Circular arc + line segments:

e.g. Q18, Q22, Q23.

Reminder:

• Friday’s instructor’s informal section. See time and place above.