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# ELECTRIC CIRCUIT

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```INSTITUT UNIVERSITAIRE
DE TECHNOLOGIE
Moutawakilou OUEDRAOGO
Option :G&eacute;nie &Eacute;lectrique, Syst&egrave;me de Contr&ocirc;le Electronique,
Informatique Industrielle
CIRCUITS
Simple Circuit
An example of a simple DC circuit is a flashlight. Batteries in the flashlight provide the DC
voltage source, the inside of the battery case usually acts as the conductor, and the lamp bulb is
the load. The flashlight has an ON and OFF switch which controls the flow of electricity. Since
there must always be a complete path for current to flow, the switch stops the flow when it is in
the OFF position. Why? Because the circuit is open when the switch is OFF. When the switch
is ON, the circuit is complete and current flows, lighting the bulb. The simple circuit is also a
series circuit.
In a series circuit, electricity has only one path on which to travel. In the example to the right,
two bulbs are powered by a battery in a series circuit. Electricity flows from the battery to each
bulb, , one at a time. Because the electricity can only flow in one path, if one of the bulbs blew
out(s’eteindre), the other bulb would not be able to light up(s’allumer) because the flow of
electric current would have been interrupted
.
In a parallel circuit, electricity has more than one path on which to travel. In the example to the
right, two bulbs are powered by(&ecirc;tre alimenter par) a battery in a parallel circuit. In this case,
because the electricity can flow in more than one path, if one of the bulbs blew out, the other
bulb would still be able to light up because the flow of electricity to the broken bulb would not
stop the flow of electricity to the good bulb
The flow of electricity depends on how much resistance is in the circuit. In our examples, the
bulbs provide resistance. In a series circuit, the resistance in the circuit equals the total resistance
of all the bulbs. The more bulbs in the circuit, the dimmer(less bright) they will light. In a parallel
circuit, there are multiple paths through which current can flow, so the resistance of the overall
circuit is lower than it would be if only one path was available. The lower resistance means that
the current will be higher and the bulbs will burn brighter compared to the same number of bulbs
arranged in a series circuit.
Conductors/Conductivity
Conductivity is the ability or power to conduct or transmit heat, electricity, or sound.
Conductors are materials that electricity easily passes through, that do not resist the flow of
electricity. Examples are copper, aluminum, steel, silver, gold, electrolytes. Not all materials
conduct electricity equally well.
Insulators
Insulators are materials that resist the flow of electricity, so electricity does not easily pass
through. Examples are plastic, wood, rubber, cloth, air, glass. Some materials are better
electricity insulators than others.
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