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Electromagnetism - Objectives

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• Force on a current-carrying wire in a magnetic field: F = BIl when field is perpendicular to current.
• Fleming’s left hand rule.
• Magnetic flux density B and definition of the tesla.
• Force on charged particles moving in a magnetic field, F = BQv when the field is perpendicular to velocity.
• Direction of force on positive and negative charged particles.
• Circular path of particles; application in devices such as the cyclotron.
• Magnetic flux defined by φ = BA where B is normal to A.
• Flux linkage as Nφ where N is the number of turns cutting the flux.
• Flux and flux linkage passing through a rectangular coil rotated in a magnetic field:
• flux linkage Nφ = BANcosθ
• Simple experimental phenomena.
• Faraday’s and Lenz’s laws.
• Magnitude of induced emf = rate of change of flux linkage
• Ɛ = N ∆ φ/∆ t
• Applications such as a straight conductor moving in a magnetic field.
• emf induced in a coil rotating uniformly in a magnetic field:
• Ɛ = BANω sin ωt
• Sinusoidal voltages and currents only; root mean square, peak and peak-to-peak values for sinusoidal waveforms only.
• I_rms = I₀/√2 ; Vrms = V₀/√2
• Application to the calculation of mains electricity peak and peak-to-peak voltage values.
• Use of an oscilloscope as a dc and ac voltmeter, to measure time intervals and frequencies, and to display ac waveforms.
• No details of the structure of the instrument are required but familiarity with the operation of the controls is expected.
• The transformer equation: N_s/N_p = V_s/V_p
• Transformer efficiency =I_SV_S/I_PV_P
• Production of eddy currents.
• Causes of inefficiencies in a transformer.
• Transmission of electrical power at high voltage including calculations of power loss in transmission lines.

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