Read
the text and select whether the statement is true (T) or false (F). Is resistance good or bad?
Resistance is a
term that describes the forces that oppose the flow of electron current in a
conductor. All materials naturally contain some resistance to the flow of
electron current.
Resistance can be
both good and bad. If we are trying to transmit electricity from one place to
another through a conductor, resistance is undesirable in the conductor.
Resistance causes some of the electrical energy to turn into heat so some
electrical energy is lost along the way. However, it is resistance that allows
us to use electricity for heat and light. The heat that is generated from
electric heaters or the light that we get from light bulbs is due to
resistance. In a light bulb, the electricity flowing through the filament, or
the tiny wires inside the bulb, cause them to glow white hot. If all the oxygen
were not removed from inside the bulb, the wires would burn up.
An important point
to mention here is that the resistance is higher in smaller wires. Therefore,
if the voltage or EMF is high, too much current will flow through small wires
and make them hot. In some cases hot enough to cause a fire or even explode.
Therefore, it is sometimes useful to add components called resistors into an electrical circuit
to restrict the flow of electricity and protect the components in the circuit.
Resistance
is also good because it gives us a way to shield ourselves from the harmful
energy of electricity.Resistance is always undesirable.