Here's a short story:

Found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives, electric motors can be powered by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or by alternating current (AC) sources, such as from the power grid, inverters or generators. Small motors may be found in electric watches. General-purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use. The largest of electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, application, type of motion output, and so on. 

Perhaps the first electric motors were simple electrostatic devices created by the Scottish monk Andrew Gordon in the 1740s. The theoretical principle behind production of mechanical force by the interactions of an electric current and a magnetic field, Ampère's force law, was discovered later by André-Marie Ampère in 1820. The conversion of electrical energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet (PM) was placed. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. This motor is often demonstrated in physics experiments, brine substituting for toxic mercury. Though Barlow's wheel was an early refinement to this Faraday demonstration, these and similar homopolar motors were to remain unsuited to practical application until late in the century. (End of story)

Provide your best guess for the following question. Give ONLY the guess, no other words or explanation.

For example:

Guess: <most likely guess, as short as possible; not a complete sentence, just the guess!>

Here are a few examples of questions and answers:

Question: When were the first electric motors developed?
Guess: 1740s

Question: By who?
Guess: Andrew Gordon

Question: What was his job?
Guess: monk

Question: Where was he from?
Guess: Scotland.

Question: Where they complex?
Guess: no

Question: What were they?
Guess: simple electrostatic devices

Question: What kind is in a watch?
Guess: unknown

Question: Are the ones in a watch big?
Guess: yes

Question: How high can the rating go on big one?
Guess: 100 megawatts

Question: How many different types of sources provide the power?
Guess: electric power source type, internal construction

Question: What does DC stand for?
Guess: direct current

Question: What about AC?
Guess: alternating current

Question: Who discovered Ampere's force law?
Guess: André-Marie Ampère

Question: When?
Guess: 1820

Question: Did Micheal Faraday show something?
Guess: yes

Question: when?
Guess: 1821

Now answer the following question in the same format.

Question: What did he change Electrical energy into?

mechanical energy