Magnetic Fields Gausss Law vs Amperes Law Amperes
- Slides: 22
Magnetic Fields • Gauss’s Law vs. Ampere’s Law • Ampere’s Law for long straight wire • Examples • Magnetic properties of materials • Force between 2 parallel wires • Motors • Loudspeakers
“Genius” • Albert Einstein Biography • National Geographic Channel, 21. 00 Tuesdays • Relativity, Nazi Germany • Walter Isaacson biography • First episode (temporarily): • http: //channel. nationalgeographic. com/genius/
Magnetism and Induction Flowchart law change field Current force direct examples Force Law 1 B → qv → F = qv x B RHR 1 charge deflection picture tube Force Law 2 B → il → F = il x B RHR 1 2 wires, motor, loudspeaker RHR 2 electromagnet solenoid Lentz generator transformer Ampere’s Law Faraday Induction B = μoi/2πr d/dt → ← i Φ = B*A → ε = dΦ/dt i = ε/R Current creates magnetic field
Gauss’s vs. Ampere’s Law • Gauss’s Law for closed surface – Flux lines penetrating closed surface equals charge enclosed. • Ampere’s Law for closed loop – Magnetic field integrated along closed loop equals current enclosed.
Ampere’s Law for long straight wire •
Right hand rule II • Right hand rule for current carrying wire
Example 20 -7 •
Example 20 -8 •
Example 20 -9
Magnetism in materials • Spinning charge particle creates magnetic field • If all spinning particles align, you have a magnet
Force between parallel wires - 1 •
Force between parallel wires - 2 a) currents same direction b) currents opposite direction action-reaction pair
Magnetism and Induction Flowchart law change field Current force direct examples Force Law 1 B → qv → F = qv x B RHR 1 charge deflection picture tube Force Law 2 B → il → F = il x B RHR 1 2 wires, motor, loudspeaker RHR 2 electromagnet solenoid Lentz generator transformer Ampere’s Law Faraday Induction B = μoi/2πr d/dt → ← i Φ = B*A → ε = dΦ/dt i = ε/R Wire 1 creates magnetic field Wire 2 feels force of that field
Example 20 -10 •
Example 20 -11 •
Problem 41 •
Problem 43 •
Problem 45 •
Rotating current loop •
DC motor • Current reverses every half turn • DC motor
DC Motor animation • DC motor animation • http: //educypedia. karadimov. info/library/Mcc. Complet. swf
Loudspeaker •