Slide 1

Chapter 30 Serway & Beichner Slide 2 Slide 3 Force between two current carrying wires Slide 4 Electric current The Ampere The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 m apart in vacuum, would produce a force between them equal to 2 10 -7 Newton per meter of length. Slide 5 Fig 30-8, p.932 Slide 6 Fig 30-9c, p.933 Slide 7 Fig 30-1, p.927 Slide 8 Fig 30-3, p.929 See Ex. 30.1 Slide 9 Fig 30-7, p.931 See Ex. 30.3 @ z = 0z >> R Slide 10 Ch. 3010 Slide 11 Fig 30-7b, p.931 Slide 12 Fig 30-17, p.938 Slide 13 Fig 30-12, p.935 for r > R for r < R Application of Ampres Law Slide 14 Fig 30-13, p.936 Slide 15 Fig 30-19, p.939 Field inside Solenoid Slide 16 Slide 17 start 9/13/04 Slide 18 Fig P30-20, p.940 Magnetic Flux B = BdA = BAcos Slide 19 Ampres Law One More Time Amperes law states that the line integral of B. ds around any closed loop equals o I where I is the total steady current passing through any surface bounded by the closed loop. Slide 20 Apply Amperes Law to red loop for a wire with a constant current I Now introduce a capacitor to interrupt the the circuit. Whats wrong? Use a power supply that will keep current constant as the cap is charged: +Q/-Q on left/right plate. Now Apply Amperes Law again. Slide 21 Now introduce a capacitor to interrupt the the circuit. If our power supply is strong enough to keep I constant, the gray surface will give B = 0! Whats wrong? Assume that I is constant. Apply Ampres Law to either the, white or gray surfaces, both of which are bounded by the red loop. This leads to: Slide 22 If the power supply can keep the current constant, the cap. will be charged: +Q/-Q on left/right plate. This establishes an E-field between the two plates. E = EdA = Q/ o Electric flux will change in time corresponding to an effective current called the Displacement Current Slide 23 Consider to different surfaces Slide 24 Fig 30-27, p.945 Orbital Motion of the Electron in an Atom Slide 25 Fig 30-28, p.946 Magnetic Moments due to Spin of electron, neutron and proton Slide 26 Table 30-1, p.946 ElectronProtonneutron -9281.41-0.966 Magnetic Moments 10 -26 J/T Slide 27 Polarization Generated Field points in the opposite direction Slide 28 Slide 29 Table 30-2, p.948 Slide 30 Paramagnetism Generated field adds to applied field Atomic currents Slide 31 Diamagnetism Generated field opposes applied field Slide 32 Magnetic Domains Slide 33 The Earth as a big magnet Slide 34 Slide 35 l =0.4 m i = 10 A Slide 36 Fig P30-6, p.957 Slide 37 Ch. 3037 Slide 38 Ch. 3038 Slide 39 Ch. 3039 Slide 40 Ch. 3040 Slide 41