The first thing I want to talk about right now is the age long romance between voltage and current in electronics.
Knowledge of electricity has been around for many years just like the concept of voltage and current. The first prominent scientists, who discovered or expounded some of the basic properties of electricity, had their names immortalized in the symbols and units of these properties. I am not going to bore you with the history of electricity; that would be a recipe for another a gist. Two most important properties of this electricity, are Voltage and Current.
VOLTAGE.
Electricity is a form of energy called electrical energy. It is a very useful form of energy and can be converted to various other forms, just like the energy it is. This energy comes about when a voltage appears at a point in time. In other words, electricity is caused by voltage. And voltage itself is established because of charge, which is the effect of electrons.
Voltage is a pressure that exists simply because of a difference in the electrical potential of two points due to dissimilar amount and/ or polarity of electrical charges. That is, the sign (type) and magnitude (size) of charge of one point of an entity relative to another point. Voltage can also be described as electrical pressure or electromotive force e.m.f, that is the force that causes electrical charge to move around. Voltage is measured in volts, symbol V.
CURRENT.
Current is the flow of charge from one point to another. In other words, current is charge in motion. To make current, there must be a closed conductive path for current to flow from the more positive point to the less positive one (or the more negative one). Current is measured in amperes or amps, symbol A.
CONVENTIONS.
Note that I have used the conventional theory representation in which the current is seen as flowing from the positive to the negative. But what happens, really, is that electrons flow from the negative to the positive. This is the electron theory representation , more on this later.
RESISTANCE.
We cannot completely discuss voltage and current without involving Resistance. Resistance is the way a entity opposes("resists") the flow of current through it. That is to say that when electricity flows though a wire (or any material for that matter; insulators, conductors, semiconductors...), the amount of current flowing, will be restricted to a certain degree. This depends on the material in question. Some materials called insulators may not even allow any current to flow at all. Resistance is measured in ohms symbol Ω.
This is all we need to know for now. We can command electronics to do a lot of things with this knowledge we have now. Now it is time to marry these three quantities in electricity that we have learnt about. Hence the romance we are talking about.
BASIC LAWS OF ELECTRICITY.
There are certain laws governing the way electricity behaves under certain conditions and the knowledge of these laws is what makes us capable of predicting circuit behaviour, hence we can design various types of gadgets and contraptions with the same basic laws. Here are some of the most important ones.
OHM'S LAW.
Even though Ohm's law is simple and obvious, it is yet the most encapsulating and apt representation of the relationship between voltage, current and resistance.
It states that "the current that flows through a material is directly proportional to the voltage applied and inversely proportional to the resistance. This means that the higher the voltage you apply across a device or "black box", the higher the current that will flow. Mind you, this will only be valid if the resistance remains the constant. The law is represented mathematically as;
I=V/R OR
V=IR OR
R=I/V
Where V is the voltage in volts, I is the current in amperes and R is the resistance in ohms. So you can calculate the voltage, resistance or current by applying one or more of the above formulas.
At the same voltage, when the resistance is high the current will be low and vice versa. Now if you apply the same voltage across two different resistors in parallel, more current will flow through the smaller resistance. In other words, current prefers the path of least resistance. It is for this reason that a person can receive a shock by touching a wire carrying a voltage.
The human body is a good conductor of low resistance, so if you touch a sufficiently large voltage especially in a wet environment, the current will be happy to flow through your body to ground. The effect is what we call electrocution or electrical shock. This depends on the kind of footwear you have on, rubber soled ones are better insulators; but it also depends on the magnitude of the voltage. This is because even known insulators can break down at very high voltages and start conducting. More so, electric sparks can jump through air at very high voltages.
When you connect devices together with wires, you must choose wire traces and thickness proportionately to carry the required current. In other words, the higher the current, the thicker the wire should be. If the current exceeds the wire rating, it will melt. This is because many more electrons are trying to flow through a very narrow pathway at the same time. The result is excessive "friction"
due to resistance and this results in heating. The temperature of the wire then rises to melting point and what do you expect?
If you connect a resistor in series with a load, you actually limit the current flowing into the load. There is usually a voltage drop across the resistor and the magnitude of this drop depends on the value of the resistor. If the current flowing through the resistor dissipates more power than the resistor can handle based on its power rating, the result is burning out of the resistor.
We shall encounter many more properties of electricity later on. Note that electronics is not magic. Always remember that good engineering practice, demands that rules be followed correctly. There are rules that can be broken in certain circumstances. Even when the rules of electricity are applied correctly, there is still room for error because many laws and properties in science can be altered by changes in its environment; not factored in at design time, these can sometimes introduce errors in the overall calculations. This is often called experimental error. So in design production, engineers usually design based on worst case scenarios to give room for error.
Expect the second part of this post soon as we review the Romantic Bonding between Voltage and Current. Please feel free to drop your comments below; I will be glad to interact further with you. Cheers.
Knowledge of electricity has been around for many years just like the concept of voltage and current. The first prominent scientists, who discovered or expounded some of the basic properties of electricity, had their names immortalized in the symbols and units of these properties. I am not going to bore you with the history of electricity; that would be a recipe for another a gist. Two most important properties of this electricity, are Voltage and Current.
VOLTAGE.
Electricity is a form of energy called electrical energy. It is a very useful form of energy and can be converted to various other forms, just like the energy it is. This energy comes about when a voltage appears at a point in time. In other words, electricity is caused by voltage. And voltage itself is established because of charge, which is the effect of electrons.
Voltage is a pressure that exists simply because of a difference in the electrical potential of two points due to dissimilar amount and/ or polarity of electrical charges. That is, the sign (type) and magnitude (size) of charge of one point of an entity relative to another point. Voltage can also be described as electrical pressure or electromotive force e.m.f, that is the force that causes electrical charge to move around. Voltage is measured in volts, symbol V.
CURRENT.
Current is the flow of charge from one point to another. In other words, current is charge in motion. To make current, there must be a closed conductive path for current to flow from the more positive point to the less positive one (or the more negative one). Current is measured in amperes or amps, symbol A.
CONVENTIONS.
Note that I have used the conventional theory representation in which the current is seen as flowing from the positive to the negative. But what happens, really, is that electrons flow from the negative to the positive. This is the electron theory representation , more on this later.
RESISTANCE.
We cannot completely discuss voltage and current without involving Resistance. Resistance is the way a entity opposes("resists") the flow of current through it. That is to say that when electricity flows though a wire (or any material for that matter; insulators, conductors, semiconductors...), the amount of current flowing, will be restricted to a certain degree. This depends on the material in question. Some materials called insulators may not even allow any current to flow at all. Resistance is measured in ohms symbol Ω.
This is all we need to know for now. We can command electronics to do a lot of things with this knowledge we have now. Now it is time to marry these three quantities in electricity that we have learnt about. Hence the romance we are talking about.
BASIC LAWS OF ELECTRICITY.
There are certain laws governing the way electricity behaves under certain conditions and the knowledge of these laws is what makes us capable of predicting circuit behaviour, hence we can design various types of gadgets and contraptions with the same basic laws. Here are some of the most important ones.
OHM'S LAW.
Even though Ohm's law is simple and obvious, it is yet the most encapsulating and apt representation of the relationship between voltage, current and resistance.
It states that "the current that flows through a material is directly proportional to the voltage applied and inversely proportional to the resistance. This means that the higher the voltage you apply across a device or "black box", the higher the current that will flow. Mind you, this will only be valid if the resistance remains the constant. The law is represented mathematically as;
I=V/R OR
V=IR OR
R=I/V
Where V is the voltage in volts, I is the current in amperes and R is the resistance in ohms. So you can calculate the voltage, resistance or current by applying one or more of the above formulas.
At the same voltage, when the resistance is high the current will be low and vice versa. Now if you apply the same voltage across two different resistors in parallel, more current will flow through the smaller resistance. In other words, current prefers the path of least resistance. It is for this reason that a person can receive a shock by touching a wire carrying a voltage.
The human body is a good conductor of low resistance, so if you touch a sufficiently large voltage especially in a wet environment, the current will be happy to flow through your body to ground. The effect is what we call electrocution or electrical shock. This depends on the kind of footwear you have on, rubber soled ones are better insulators; but it also depends on the magnitude of the voltage. This is because even known insulators can break down at very high voltages and start conducting. More so, electric sparks can jump through air at very high voltages.
When you connect devices together with wires, you must choose wire traces and thickness proportionately to carry the required current. In other words, the higher the current, the thicker the wire should be. If the current exceeds the wire rating, it will melt. This is because many more electrons are trying to flow through a very narrow pathway at the same time. The result is excessive "friction"
due to resistance and this results in heating. The temperature of the wire then rises to melting point and what do you expect?
If you connect a resistor in series with a load, you actually limit the current flowing into the load. There is usually a voltage drop across the resistor and the magnitude of this drop depends on the value of the resistor. If the current flowing through the resistor dissipates more power than the resistor can handle based on its power rating, the result is burning out of the resistor.
We shall encounter many more properties of electricity later on. Note that electronics is not magic. Always remember that good engineering practice, demands that rules be followed correctly. There are rules that can be broken in certain circumstances. Even when the rules of electricity are applied correctly, there is still room for error because many laws and properties in science can be altered by changes in its environment; not factored in at design time, these can sometimes introduce errors in the overall calculations. This is often called experimental error. So in design production, engineers usually design based on worst case scenarios to give room for error.
Expect the second part of this post soon as we review the Romantic Bonding between Voltage and Current. Please feel free to drop your comments below; I will be glad to interact further with you. Cheers.
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