Page 277 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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Electrical systems 261

Figure 3.5 Magnetic effect

Figure 3.6 Reversibility: motor and generator

Switch Current
(closed) flow

The battery The bulb has
a resistance
has a voltage
or pressure. to flow.
V A higher
A higher
resistance will
pressure will P R
make more reduce the
flow of
current flow
current
The power of a bulb says how
much electrical energy it will
convert to heat and light. Higher
power makes more light so more
current will flow
Figure 3.7 Basic circuit

Any one value can be calculated if the other two are known. This relationship is
stated in a law called Ohm’s law.
Ohm’s law states that in a closed circuit the current is proportional to the voltage
and inversely proportional to the resistance. This means:
Voltage Current Resistance

(V IR ) or (R V ) I / or (I V / ) R