Paper 2 Alternating Current Generators Drills

Q1 Peak emf

A coil with $80$ turns and area $3.0\times 10^{-3}{\mathrm{m}}^2$ rotates in a uniform magnetic field of flux density $0.45\mathrm{T}$ at $25\mathrm{rev}{\mathrm{s}}^{-1}$.

1. Calculate angular speed. [1]
2. Calculate peak induced emf using ${\mathcal{E}}_0=NBA\omega$. [3]
3. State one way to increase the peak emf. [1]

Q2 Flux and emf Phase

1. Explain why the emf is zero when flux linkage is maximum. [2]
2. Explain why the emf is maximum when flux linkage is zero. [2]
3. State the phase difference between sinusoidal flux linkage and induced emf. [1]

Q3 Slip Rings

1. State the purpose of slip rings and brushes. [2]
2. Explain why the output is alternating. [2]