Electricity Alternating Current
- 3. Electricity Electricity is the flow of charges. Charge is often carried by electrons in a metal wire, by ions in an electrolyte or by both ions and electrons in an ionised gas. ELECTRIC CURRENT
- 5. Welcome “Don’t touch …the results could be shocking”
- 7. Direct current (DC) vs. Alternating Current (AC)
- 8. Alternating Current (AC) -220V An Alternating current or voltage is defined as one whose magnitude changes with time and whose direction reverses at regular repeating intervals. DCAC
- 9. GENERATION OF AC “A generator utilizes the relationship between electricity and magnetism to convert mechanical energy into electrical energy. When an electric conductor (such as a loop of wire) and a magnetic field move relative to each other, a voltage is induced in the conductor.”
- 10. GENERATION OF AC
- 11. EMF INDUCED IN A ROTATING COIL IN A MAGNETIC FIELD Consider a coil of N turns and area A being rotated at a constant angular velocity ω in a magnetic field of intensity B, its axis being perpendicular to the field . Let the normal to the coil make an angle θ with the direction of B. Then the flux linked with N turns of the coil at any instant t is given by Flux (ϕ)= BAN cos(ω)t, since θ = ωt.
- 12. MAGNETIC FLUX Magnetic Flux is defined as the number of magnetic field lines passing through a given closed surface. It gives the measurement of the total magnetic field that passes through a given surface area. Flux (ϕ)=B.A = BAN cosϴ Φ is the magnetic flux B is the magnetic field A is the area θ the angle at which the field lines pass through the given surface area
- 13. EMF INDUCED IN A ROTATING COIL IN A MAGNETIC FIELD Flux (ϕ)= BAN cos(ω)t, since θ = ωt. From Faradays Law, the induced EMF for the rotating coil of N turns is then
- 14. EMF INDUCED IN A ROTATING COIL IN A MAGNETIC FIELD is the maximum value of e.m.f
- 15. Peak Value Instantaneous Value Peak value of an AC is the maximum value of current in either direction -1 0 1