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This mini-explosion pushes the piston back down, and as it rises
again the fumes formed by the ignition are forced out through the
exhaust valve.
This cycle is repeated many times per second. The moving
piston makes the crankshaft rotate at great speed.
The crankshaft extends directly to an alternator, which
consists of two main sets of windings - coils of insulated copper
wire wound closely around an iron core. One set, called stator
windings, is in a fixed position and shaped like a broad ring. The
other set, the armature windings, is wound on the rotor, which is
fixed to the rotating crankshaft. The rotor makes about 3,000
revolutions per minute.
The rotor is magnetized and as it spins round, electricity is
generated in the stator windings through the process of
electromagnetic induction. The electric current is fed to the output
terminals or sockets. This type of generator can produce a 700watt
output, enough to operate lights, television, and some domestic
appliances. Larger versions provide emergency power to hospitals
and factories.
Source adapted from Inside out: Portable generator.
Education Guardian.

Step 4

Study this text on the four-stroke cycle. Then label each stroke
correctly.

In the four-stroke cycle, the piston descends on the intake
stroke, during which the inlet valve is open. The piston ascends on
the compression stroke with both valves closed and ignition takes
place at the top of the stroke. The power or expansion stroke
follows. The gas generated by the burning fuel expands rapidly,
driving the piston down, both valves remaining closed. The cycle
is completed by the exhaust stroke, as the piston ascends once
more, forcing the products of combustion out through the exhaust
valve. The cycle then repeats itself.

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