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Electric Current: Electric current is simply the flow of electric charge. In solid conductors the flow of electrons and in fluids the flow of ions as well as electrons constitutes the current. An electromotive force (emf), provided by a cell of a generator, is essential to maintain a continuous flow of current in a circuit.
Electrical Resistance: When electric current flows through a conductor, e.g. a metallic wire, it offers some obstruction to the current. This obstruction offered by the wire is called its electrical resistance. The resistance (R) of a wire of a given material depends on its length (l) and the area of cross section (a)
R = ρl / a
If the wire has a circular cross section of radius r, then a = ∏ r. Thus,
R = ρl / ∏ r
ρ is a constant called the resistivity of the material of the wire. Resistivity of a good conductor (e.g. copper, silver, etc) increases with temperature, whereas, resistivity of a semiconductor (e.g. carbon) decreases with increasing temperature.
Electrical Resistance: When electric current flows through a conductor, e.g. a metallic wire, it offers some obstruction to the current. This obstruction offered by the wire is called its electrical resistance. The resistance (R) of a wire of a given material depends on its length (l) and the area of cross section (a)
R = ρl / a
If the wire has a circular cross section of radius r, then a = ∏ r. Thus,
R = ρl / ∏ r
ρ is a constant called the resistivity of the material of the wire. Resistivity of a good conductor (e.g. copper, silver, etc) increases with temperature, whereas, resistivity of a semiconductor (e.g. carbon) decreases with increasing temperature.
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Electric current is the flow of electrons. In a better way, we can say that it is the flow of impulse.
One more important factor of electricity is resistance.
it opposes the flow of electric current.
According to OHM's LAW:
Voltade = Current * Resistance
The voltage across the conductor is directly proportional to the current through the conductor.
where "R" is the proportional constant.
Suppose, we don't oppose flow of high voltage current: let's take the example of MSEB, where large KOHMs resistors are being used. If they hadn't used them , then all electrical appliances would have been burnt.
One more important factor of electricity is resistance.
it opposes the flow of electric current.
According to OHM's LAW:
Voltade = Current * Resistance
The voltage across the conductor is directly proportional to the current through the conductor.
where "R" is the proportional constant.
Suppose, we don't oppose flow of high voltage current: let's take the example of MSEB, where large KOHMs resistors are being used. If they hadn't used them , then all electrical appliances would have been burnt.
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