急!! phy emf!!!

2010-05-12 7:19 am

急!!phy emf

好急呀，有幾個問題唔識答:

1: Describe how the rate of change of magnetic flux, the no. of turns of coil and its cross-sectional area affect the induced emf?

2: Explain why the coils shoudl be wound around the middle of the solenoids?

3: Determine the relationship between the rates of change of magnetic flus for the small solenoid and large solenoid? What is the conclusion?

請教教我…

回答 (1)

天同

2010-05-12 7:51 am

✔ 最佳答案

1. I suppose you are referring to a fixed coil placed in a time varying magnetic field.
By Faradya's Law, the induced enf is proportional to the rate of change of magnetic flux linked with the coil.
Hence, induced emf E = d(N.A.B)/dt
where N is the number of turns of the coil, A is the cross-sectional area of the coil, and B is the magnetic flux density.
Therefore, E = N.A.(dB/dt)

2. Are you referring to any experiment? The question alone doesn't make any sense at all.
If it were an experiment to investiage induced emf, the most important point was to ensure a uniform magnetic field. It could be achieved at the middle of a long solenoid.

3. Again, are you referring to an experiment? How do the two solenoid relate to each other? You need to give some description to it.

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