Electromagnetic induction and A.C. lab
Explore moving conductors, changing flux linkage, Lenz’s law and generator waveforms to connect induced e.m.f. with current direction.
Learning goals
- Use magnetic flux and flux-linkage relationships.
- Apply Faraday's and Lenz's laws to induced e.m.f. and direction.
- Explain simple applications of electromagnetic induction, including motional e.m.f. and eddy currents.
- Explain simple iron-core transformer operation and apply ideal transformer ratios.
A 100-turn coil of area 100 square centimetres rotates at 5 hertz in a 0.2 tesla field; the peak e.m.f. is 6.28 volts. Flux linkage 200 milliwebers, e.m.f. 0 volts.
- Flux linkage, NΦ
- 200 mWb
- e.m.f., ε
- 0 V
- Peak e.m.f., NBAω
- 6.28 V
- Current, I
- 0.160 A
- Force on rod, BIL
- 0.00640 N
- Power in R, I²R
- 0.0128 W
- Magnet speed
- 0 m/s
Try this
0 of 4 doneStop the coil where the e.m.f. is largest: pause it or drag it round. (not done yet)
The e.m.f. peaks when the coil's plane is parallel to B: NΦ is zero there but changing fastest.
Make the coil's peak e.m.f. 10 V. (not done yet)
ε₀ = NBAω: doubling N, B, A or f doubles the peak e.m.f., and a faster rotation also shortens the period.
Release the rod and watch it come to rest. (not done yet)
The induced current makes a force BIL that opposes the motion (Lenz's law), so the rod's kinetic energy becomes heat in R.
Drop the magnet right through the coil. (not done yet)
The two pulses have opposite signs because the flux linkage rises then falls; the second is larger and shorter because the magnet is faster.
You’ve tried every task.