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Current Electricity (Conductors (Metals that allow a current of electrons…
Current Electricity
Conductors
Metals that allow a current of electrons to pass easily through it
All metals are electric conductors
Electron current flows from the negative to positive terminals
Conventional current flows form the positive to negative terminals
SI unit for measuring the electric current using the ammeter is Ampere (A)
Potential difference and electromotive force
The electric pressure difference is known as the potential difference.
SI unit for measuring the potential difference using the voltmeter is the Volt (V)
The force by which the (-) terminal of the electric source realeases electrons the the external circuit is known as the Electromotive force (EMF)
In order for a current to flow through a conductor, it is necessary for a potential difference to exist across it
Relationship between current flow and potential difference of a conductor (Ohm's Law)
When the temperature of a conductor remains constant, the current passing through the conductor is directly proportional to the potential difference
Unit for measuring resistance using an Ohm meter is Ohm ( )
V
= I/R
At constant temperature
A current of electric charges flowing through a conductor is known as an electric current
Charges that are found stationary on an object are known as Electrostatic charges
When electrostatic charges begin to move they give rise to an electric current
Factors affecting the resistance of a conductor
Area of the cross section of the segment of the conductor
Resistance decreases when the area increases
Length of the segment of a conductor
Resistance increases when length increases
Material composition of a segment of a conductor
Differs according to the material ((a.k.a. - resistivity)
Resistors
The current through a circuit decreases with the increase of resistance
Types
Fixed value resistors
Variable resistors
Light dependent resistors
Combination of resistors
Series Combi.
V
= IR
Parallel combi.
1/R = 1/R1 + 1/R2