Points noted

 

Demonstrating rectification and filtering is an entirely different area, Consider that in the basic electricity courses, semester one is DC circuits, while semester two is AC circuit theory. Of course, those courses go into much deeper theory than the basic introduction.
And I am not aware of what level is being taught. Are these students younger or older?? That matters a bit.And is this an electricity class, or a physics class?

 

A-level students look at induction and the various components of electronic circuits in electronics study groups and in physics. I need to rectify it sufficiently to get a stable DC output to run something suitable without too much of a noisy input.

 

Demonstrating rectification and filtering is an entirely different area, Consider that in the basic electricity courses, semester one is DC circuits, while semester two is AC circuit theory. Of course, those courses go into much deeper theory than the basic introduction.
And I am not aware of what level is being taught. Are these students younger or older?? That matters a bit.And is this an electricity class, or a physics class?

In most engineering programs, the first semester is linear circuits and systems and covers both DC and AC circuits, the second semester is usually transform methods, again only for linear systems. While both courses generally cover opamp circuits, they seldom even mention the word diode or transistor in the text. These are the purview of the third and later courses, which generally focus on solid state electronics.

While I understand this division between linear and nonlinear, I think it would be better to get diodes and transistors introduced much earlier on so that students can work with and design interesting and moderately useful circuits very early on.

 

OK, now getting a useful output is quite different from just demonstrating induction. Probably a DC motor, or a synchronous motor, hand cranked, can power a light bulb. Or a high power LED .

 

I have a few hand-cranked flashlights that I got in a swag bag. The whole thing is roughly spherical about the size of a quarter cross section. I was actually a bit surprised how long the LED will operate on just a few seconds of cranking. But with modern LEDs, we are only talking about something like maybe 50 mW to perhaps a couple hundred milliwatts. A well-designed hand-cranked generator can likely output a few watts, perhaps may even ten to twenty watts, but the person cranking it probably couldn't keep it up very long (but long enough for a demo). This is one of those areas where the Internet is flooded with snake oil claims of hand-cranked generators producing 1000 W or more, so it's hard to find realistic information.

 

You guys are missing a very easy demonstration that gives a real easy to see and hear result. An electric guitar. The pickups are permanent magnets wrapped in wire and the string when strummed cases the induction by varying the magnetic field.

 

Yes it’s an alternative demo but a different expression of the principle of induction. Besides, I don’t have an electric guitar to bring to a tutoring session

 

Besides, I don’t have an electric guitar to bring to a tutoring session

Bet one of you students do. It's still magnet to electic induction.

 

For a demonstration to be the most informative, all of the elements should be clearly visible and the function should be obvious. So not all of the suggestions include both requirements.
An electric guitar would certainly be good for a discussion, but not for a demo.