3 Indukovano elektromagnetno polje – problemi i rješenja
1. Zavojnica zamijenjena drugom zavojnicom koja ima petlje 2 puta veće od početnih petlji i brzina promjene magnetskog fluksa je konstantna. Odredite odnos početne i konačne indukovane elektromotorne sile.
Poznato:
Početne petlje (N) = 1
Završne petlje (N) = 2
Brzina promjene početnog magnetskog fluksa (ΔØB / Δt) = brzina promjene konačnog magnetskog fluksa (ΔØB /Δt)
Wanted: The ratio of initial and final induced emf
Rešenje:
The equation of Faraday’s law of induction :
E = -N (ΔØB /Δt)
E = induced EMF, N = number of loops, ΔØB / Δt = the rate of change of magnetic flux
The ratio of initial and final induced emf :
E initial: E final
-N (ΔØB / Δt) : -N (ΔØB /Δt)
1: 2
2. In the initial state (1), the magnetic flux is changed by 5 Wb in 2 seconds on a coil with 20 loops. In the final state (2), the same flux changed in 8 seconds. Determine the ratio of the initially induced emf and the final induced emf.
Poznato:
Brzina promjene početnog magnetskog fluksa (ΔØB / Δt) = 5/2
The rate of change of final magnetic flux (ΔØB / Δt) = 5/8
Number of loops (N) = 20
Wanted: The ratio of the initially induced emf and the final induced emf
Rešenje:
E initial: E final
-N (ΔØB / Δt) : -N (ΔØB /Δt)
20 (5/2) : 20 (5/8)
5/2: 5/8
1/1: 1/4
4: 1
3. The magnetic flux of the initial coil has 200 loops changes by 0.06 Wb in 0.4 seconds. The magnetic flux of the final coil has 0.08 Wb in 0.2 seconds. If several loops of the final coils are substituted with the half number of the first coil’s loops, determine the ratio of the induced emf of the initial loops and the final loops.
Poznato:
Brzina promjene početnog magnetskog fluksa (ΔØB / Δt) = 0.06 / 0.4
Number of initial loops (N) = 200
The rate of change of final magnetic flux (ΔØB / Δt) = 0.08 / 0.2
Number of final loops (N) = 100
Traži se: The ratio of the initial induced emf and the final induced emf
Rešenje:
E initial : E final
-N (ΔØB / Δt) : -N (ΔØB /Δt)
200 (0.06/0.4) : 100 (0.08/0.2)
2 (0.15) : 1 (0.4)
0.3: 0.4
3: 4
