Current is the flow of electrons in a conductor. matter is made up of atoms. electrons are loosely bound to the nucleus so they can loosen up and move around when voltage is applied.
Conductors allows the flow of electrons this terminology is called current.
Volts
- Volt is the SI unit of electric potential, voltage and electromotive force. imagine a fluid pipe connected to a pump to understand the narrative. The more the pressure the greater the force, this will also increase the flow of water pushing through the pipe.
- The voltage is like a pump pushing electrons around the circuit. The higher the voltage applied to a circuit, the higher the current that will be forced through it.
Amps
An amp is the unit of electric current that measures the flow of electrical charge through a conductorLoad
- is any device connected to a voltage source that consumes energy. It could be a simple appliance like television set, an air conditioner, a lightening bulb.
In the circuit above, a voltage V pushes a current I around the circuit and through the load. As you may remember, this could be a device such as an air conditioner or a lightening bulb. The load resists the flow of current and the magnitude of its resistance is R ohms. This phenomenon is known as Ohms Law.
V = I R
This law basically explains the relationship between the current(I) and resistance (R).
It states the current is proportional to the voltage and inversely proportional to the resistance meaning as resistance increases current decreases and vice versa.
An example:
If the resistance in a system applied is 100 ohms and has a voltage of 120 its current is calculated to be;
V=IR
.: I=V/R
120 / 100 = 1.2 amps
Alternative Way of Working Out Power
W = IV
But also, P =IV
but remember from ohm's law I= V/R
So, substituting the expression I =V/R into P = IV gives:
P = IV = (V/R) V = V2/ R
similarly
P = IV =I(IR) = I2R
here is an example.
A 240 volts supply is connected to a load of 100 ohms. What will be the power consumption?
Power = V2/ R = (240)2 / 100 = 576 watts
Basic equations to know
Insulators
These are materials possessing high resistance. they do not allow free flow of electric current hence termed non-conductors.
some examples are plastic materials, wood and timber, however it is to note that when these materials are mixed or joined with certain conductors like water, they tend to gain charge this is because water allows free flow of electrons.
Electrical resistivity is the reciprocal of electrical conductivity. It is a fundamental property that measures how strongly a material resists the flow of electric current. This also means the larger the cross-sectional area A, the smaller its resistance.
Copper has the lowest resistivity of most common materials, and this is why it is widely used in the manufacture of cables. Silver has a lower resistivity than copper, but it is much more expensive. Aluminum is generally used for overhead cables and although it has a higher resistivity than copper, it is lighter. Gold has a resistivity about 1.5 times that of copper, however it is unreactive and doesn't deteriorate.
It can be calculated with the formula
R = ρL / A
ρ (Greek letter "rho") is a constant known as the resistivity and is a measure of how good the material is at conducting electricity. L is the length and A the cross-sectional area of the material.
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| Resistivity of some materials |
Voltage Regulator
Voltage regulator is a system that automatically maintains a constant voltage, using electromechanical or electronic components. these devices are implemented as single ICs or separate modules consisting of several discrete components or integrated circuits.
A regulator that reduces voltage is called a buck regulator and one that increases voltage is called a boost regulator.The output of an unregulated voltage supply will drop as current increases. This is because of internal resistance which causes a potential drop as current flows.
A regulator that reduces voltage is called a buck regulator and one that increases voltage is called a boost regulator.
The output of an unregulated voltage supply will drop as current increases. This is because of internal resistance which causes a potential drop as current flows.
Electric sparks
An electric spark is an abrupt electrical discharge that occurs when a sufficiently high electric field creates an ionized, electrically conductive channel through a normally insulating medium, often air or other gases or gas mixtures. Michael Faraday described this phenomenon as "the beautiful flash of light attending the discharge of common electricity"
This produces a flash of visible light, heat, UV radiation and sound. The voltage required to produce a spark is about 3000 volts per mm between rounded electrodes in air. Sparks can be small, e.g. lightening, wire bridge, spark from a generator plug etc.
When clouds get charged up, voltage becomes so high that a spark jumps from cloud to cloud or cloud to ground. The flash we see is called lightening and the sound we hear is call thunder this is caused by the explosive heating and expansion of air by the electrical discharge.
