There are a lot of technical terms in the electrical and electronics world that can be pretty confusing to a layperson, especially when they seem related. If you’ve ever heard the saying “you can’t have one without the other,” that’s exactly the case with amps and volts.
While you may already know that both are somehow related to the measurement and regulation of electric power, it can be tricky to wrap your head around them. These two very important concepts are integral to understanding the flow of power in a circuit.
In this article, we’ll delve into the world of electricity and pit amps against volts to explore the differences between them in depth. Some examples would also go a long way in demystifying them, so we’ve made sure to provide a few helpful ones so you can better understand how these two concepts work together. So, let’s dive right in!
Amps vs Volts: Side-by-Side Comparison
| Amps | Volts | |
|---|---|---|
| Named After | André-Marie Ampère | Alessandro Volta |
| Definition | A measure of current flow | A measure of potential difference |
| Unit of measurement | Amperes (A) | Volts (V) |
| Base Unit | Yes (International System of Units) | No (Derived Unit) |
| Formula | I = Q/t | V = J/C |
| Relationship with Resistance | Inversely proportional | Directly proportional |
| Relationship with Power | Directly proportional | Directly proportional |
Amps vs Volts: What’s the Difference?
Definition
Amps, short for amperes, are a measure of electric current flow. They represent the amount of electrical charge that passes through a circuit or wire per unit of time. Think of amps as the measure of the “amount” of electricity flowing through a circuit with respect to time.
When we talk about amps, we’re essentially asking, “how much electricity is passing through this conductor?” You can also think of amps as the amount of water flowing through a pipe — the more amps, the more electricity is flowing.
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Volts are a bit different. Volts represent the electrical potential difference between two points in a circuit. They measure the “force” that’s pushing the electricity through the circuit. Using the water analogy above, volts are the equivalent of water pressure.
They are a measure of how much “pressure” is pushing the electricity through the circuit. The higher the voltage, the more force there is pushing the electricity through the circuit. In simpler terms, amps measure the amount of electricity while volts measure the strength or intensity of that electricity.
Derivation
Current (Amps)
An ampere is a base unit of the International System of Units (SI) with the symbol “A” used for measuring electric current, as we’ve seen. Electric current itself is the rate at which electric charge flows through a conductor. One ampere of electric current is defined as the flow of one coulomb of electric charge per second through a conductor.
In mathematical terms, electric current (I) can be expressed using the following equation:
I = Q/t
For example, if a conductor has a charge of 6 coulombs flowing through it in 3 seconds, the current through the conductor would be:
I = Q/t = 6C / 3s = 2A
Where I is the electric current in amps, Q is the amount of electric charge in coulombs, and t is the time in seconds. Therefore, the electric current through the conductor is 2 amps.
Voltage
Volts, on the other hand, are a derived unit of measurement. This means that voltage is not a base unit, but instead, is calculated based on other base SI units.
Specifically, volts are calculated based on the relationship between energy and electric charge. By definition, one volt is the amount of energy required to move a unit of electric charge from one point to another in an electric field.
Joules represent the amount of energy being transferred. One volt is therefore equivalent to one joule of energy per one coulomb of electric charge.
This is expressed mathematically as:
Volts (V) = Joules / Coulomb
To put it all together, let’s say, using our previous example with a conductor, that the energy required to move this charge is 18 joules.
Using the equation above, we can calculate the voltage of the conductor as follows:
V = J/C = 18J / 6C = 3V
Therefore, the voltage across the conductor is 3 Volts.
Power
By multiplying the voltage and current, we can even calculate the power being used using the formula:
Power = Volts x Amperes
In our example, this would be:
Power = 3V x 2A = 6 watts
Relationship with Resistance
Amps, volts, and resistance are related quantities. Resistance is the measure of how difficult it is for electrons to pass through the circuit.
Using our previous water analogy, you can think of their relationship in this way: if amps measure the flow of water through a pipe, volts measure the pressure of the water in the pipe, while resistance measures the diameter and length of the pipe itself.
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Ohm’s Law is the key to understanding how these three variables relate to each other. It states that the current (I) flowing through a circuit is directly proportional to the voltage (V) applied to the circuit and inversely proportional to the resistance (R) of the circuit. This is expressed mathematically as:
I = V/R
This means that if you increase the voltage in a circuit, the current flowing through it will also increase, assuming the resistance stays the same. Similarly, if you increase the resistance in a circuit, the current flowing through it will decrease, assuming the voltage stays the same.
Using our previous example, if the voltage is 3V and the current is 2A, then according to Ohm’s Law, the resistance in the circuit must be:
R = V/I = 3V / 2A = 1.5Ω (Ohms)
If we increase the voltage to 9 volts while retaining the same circuit (i.e keeping the resistance the same):
I = 9V/1.5Ω = 6A
Direction of Flow
Another key difference between amps and volts has to do with their respective directions when it comes to current flow. Electric current flow is the movement of electric charges (usually electrons) through a conductor in a specific direction.
The direction of electron current (which is opposite to conventional current) is from the negative terminal of a voltage source to the positive terminal. Current, therefore, flows from higher potential (higher electron concentration) levels toward lower potential levels.
Voltage, on the other hand, does not have a direction of flow. It only represents the difference in electrical potential between two points in a circuit — a point of higher potential and a point of lower potential (eg. positive and negative terminals).
Please note that in some cases, such as semiconductors, current flow may be designated as the movement of positive charges (holes) in the opposite direction (from the positive to the negative terminal).
Amps vs Volts: 5 Must-Know Facts
- The SI unit for electric current, Ampere is named after André-Marie Ampère. Ampère was a French physicist and mathematician who was among the pioneers of electromagnetism.
- The SI unit for electric potential difference, Volt is named after Alessandro Volta. He was an Italian physicist who’s credited with being the inventor of the electric battery.
- A Watt (W) is equal to one joule per second and can be calculated by multiplying volts by amps (P = V x I). Watts measure both current flow and voltage at once. They tell us how much power an appliance draws when connected to an electrical source with a certain voltage level and current flow rate.
- Transformers are devices used to increase or decrease the voltage in an electrical circuit in a process called induction. In doing so, they increase or decrease the current in the transformer coils inversely.
- A lightning strike contains incredibly high amounts of energy which causes large spikes in both voltage and amperage throughout any affected area.
Amps vs Volts: Which One Is Better? Which One Should You Choose?
As we saw earlier, volts and amps go hand-in-hand; you can’t have one without the other. As such, there is no specific answer as to which one is “better.” Rather, it depends on what the situation at hand is.
So, say, electric power needs to be transmitted over long distances — then it’s better to raise voltage rather than amps. That’s because the resistance of the transmission line is proportional to the length of the line and the current flowing through it.
As a result of Ohm’s law, as the resistance of the transmission line increases with distance, a higher voltage is required to maintain the same amount of current. If high amperage was used instead of high voltage, the resistance of the transmission line would cause significant energy loss due to heat generated by the current. This would result in a substantial loss of power over long distances.
On the other hand, if the goal was to determine the amount of power being consumed by an electrical appliance at home, then amps would be the better choice.
This is because the voltage of most appliances is fixed, and the current they draw is proportional to their power consumption. In addition, measuring amps can also help detect any potential issues within circuits, such as shorts or overloads.
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