Unit 2.1- Conduction Of Electricity

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Current flows around any circuit where there is a potential difference.
Current: Rate of flow of charge
Electrons: negatively charged particles that can move in metals
Current: The flow of electrons
Electrons flow from the negative to the positive terminal in a circuit.
Ammeters measure the current flowing through a circuit/component.
Ammeters are connected in series to measure the current of a circuit.
I = ΔQ / Δt
Current moves in the opposite direction to the electrons.
Current moves from the positive to the negative terminal.
The unit of current is Amperes (A).
The total current entering a junction is equal to the total current leaving a junction.
Kirchhoff's first law: The total charge of a circuit is always conserved.
Mean drift velocity: the average distance travelled by an per unit time.
Electrons move randomly when no potential difference is applied to a wire.
Electrons move in the positive direction when a potential difference is applied to a wire.
The more electrons a wire has, the more current it can carry.
The more electrons a wire has, the more resistance it can also have.
Conductors have high electron densities of around 10²⁹.
Semiconductors have electron densities of around 10¹⁹.
Insulators have low electron densities of around 10⁹.
Potential difference = Voltage
Potential difference: The work done in the circuit per unit of charge.
Potential difference is measured in Volts (V).
Potential difference of a circuit or component is measured by connecting a voltmeter in parallel.
V = W / Q
Electromotive force: total voltage produced by a cell, but not all of it may reach the circuit.
Electromotive force (EMF) is measured in Volts (V).
EMF = (r + R) * I
EMF is always greater than the voltage of a circuit.
Resistance: The opposition to the flow of electrons in a circuit.
Ohm's law: The current is directly proportional to the potential difference.
R = V / I
As the current increases, the resistance decreases.