A copper coil, a magnet, and a repetitive source of motion is not that hard. You’d have to go really far back not to have access to a mill, and even if you did, it wouldn’t be that hard to invent a hand crank. The question is how you make the electricity useful. I think a simple heating element is probably the best option. Show them the river cooking their food, and the benefits should be obvious

jokes on you, I watched dr stone

While I have a basic understanding of using magnets and wires for motors/generators, I think an easier option would instead be a Van de Graaff generator.

Then probably get executed for witchcraft or just ignored as a lunatic for speaking in a strange foreign tongue.

You might think it’s a bunch of formulas like V = W / Q and V = I × R and all that junk

But no

Erase math from your mind for only a moment

Ionic Compounds molecules have charges, you have negatively charged anions and positively charged cations. This stuff exists everywhere: NH+, O-, Ag+, etc. Best way to identify them is to first set up a periodic table, probably pretty difficult for a layman to remember the rules, and then you can test to identify materials placement on the table with flame tests (different metals burn a different color when placed in a flame). Positive materials or the positive end of a polarized material are commonly referred to as Cathodes, and negatives are Anodes.

Magnetism is important, but you don’t need to know about the specifics of electron valence or orbitals to understand electricity. Magnets are naturally occurring and you can make most ferrous metals into magnets just by heating them to their curie point or by hitting or stroking them.

Once you have some copper, a magnet, and some positively (P) and negatively (N) charged materials you can set up some simple circuits. The materials can be oriented in large PN junctions to work as batteries, in small PN junctions to work as diodes which control the direction of flow of electricity, and in small PNP junctions with a glass plate at the end to create Light Emitting Diodes. Small capacitors can also be made with metallic conductive material sheets layered with non conductive dialectic components like glass or paper.

One of the earliest and most common battery formulas would be Lead Acid batteries. By layering Lead Dioxide as a Cathode and solid metal Lead as an Anode in an Electrolyte solution, ideally 1.25 to 1.28 kg of sulfur per liter of water makes a good battery acid. You can create sulfuric acid by burning naturally occurring sulfur and directing the resulting gasses into a container of water.

Once you have your rechargeable battery, you can charge it by spinning a magnet around inside of big coil of copper wire attached to the positive and negative end of your battery. The copper has its own electromagnetic field through which electron excitation is dispersed, and by moving the magnetic field of the copper with your magnet’s magnetic field you’re inducing flow through the copper in a specific direction.

I’m not going to get into the details of Alternating vs Direct currents, but I will add the concept of a Transformer which is where you place two conductive and charged materials in close proximity allowing it to Arc and jump over on its own, which would naturally convert AC to DC, useful in current cleaning and regulation.

Congratulations, you’ve just brought turbines, lights, batteries and electric engines to Rome. Now, kindly return to your present to promptly discover the horrible eternal empire you’ve created and suffer the rest of your meaningless peasant life.

How to Invent Everything: A Survival Guide for the Stranded Time Traveler

Tbf, I sincerely hope a lot of you understand the basic concept of a gearbox. Depending on how far back you go, a water wheel might be a pretty massive leap forward, and it might at least inspire other, smarter people of the time to work on theories of energy, and eventually electricity.

I think my go-to invention would be some kind of bicycle or something that uses a similar mechanism

After that take this rock and show me how you taught it to do maths

Creepy soldiers covered in blood worshiping Jesus background.