What is the Difference Between Voltage and Current? .Voltage and current are two fundamental concepts in electrical engineering, and understanding the difference between them is crucial to developing a deeper understanding of how electricity works. In this technical blog, we’ll explore the key differences between voltage and current, including their definitions, units of measurement, and practical applications.
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Important electricity terms
- Conductors and Insulators: Good conductors are materials that let electricity flow through them easily. Most metals are good conductors, which is why metal is used in electrical wiring all over the world. The opposites of conductors are insulators. Insulators don’t carry electricity well. We need insulators to protect people from flowing electricity. Rubber and plastics are examples of good insulators.
- Voltage: is the force that makes electrons flow. It’s a difference in potential energy between two different points in a circuit.
- Current: is the rate of the flow of electrons. It’s measured in amperes, which are also called amps.
- Power (Watts): The power used in a circuit is measured in watts. Watts are calculated by multiplying the voltage by the current.
- Resistance: This is the measure of how well something conducts electricity. If it has a low resistance, the object is a great conductor of electricity, and if it has a high resistance, that means that it doesn’t conduct electricity well.
What is Voltage?
also known as electric potential difference, is the measure of the electric potential energy per unit charge. In simpler terms, voltage is the force that drives electrons to flow through a circuit. It is the potential difference between two points in a circuit, which allows for the transfer of energy from one point to another. Voltage is measured in volts (V), which is defined as one joule of energy per coulomb of charge.
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Voltage can be compared to the pressure in a water pipe. Just as water flows from an area of high pressure to an area of low pressure, electrical current flows from a point of higher voltage to a point of lower voltage. A higher voltage difference means that there is more energy available to drive current through a circuit.
Formulas:
The basic formula is given below.
V = J/C = W/A … (in Volts)
Where:
- V = Voltage in Volts
- J = Energy in Joules
- C = Charge in Columbus
- W = Work done in joules
- A = Current in Ampere
in DC Circuits
- V = I x R
- V = P / I
- V = √ (P x R)
in 1-Phase AC Circuits
- V = P/(I x Cosθ)
- V = I / Z
in 3-Phase AC Circuits
- VL = √3 VPH or VL = √3 EPH (Star Connection)
- VL = VPH (Delta Connection)
Where:
- I = Current in Amperes (A)
- V = Voltage in Volts (V)
- VL = Line Voltage
- VPH = Phase Voltage
- P = Power in Watts (W)
- R = Resistance in Ohm (Ω)
- Z = Impedance = Resistance of AC Circuits
- Cosθ = Power Factor
Read More : Voltage Source Inverter vs. Current Source Inverter
What is Current?
the flow of electric charge through a circuit. It is measured in amperes (A), which is defined as the amount of charge that passes through a point in a circuit per second. The flow of current in a circuit is due to the movement of electrons, which are negatively charged particles. Electrons flow from the negative terminal of a voltage source to the positive terminal, completing a circuit and allowing for the transfer of energy.
Current can be compared to the flow rate of water in a pipe. Just as the flow rate of water is measured in gallons per minute, the flow of electrical current is measured in amperes. The rate at which current flows through a circuit depends on the voltage applied and the resistance of the circuit. A higher voltage or lower resistance will result in a greater flow of current.
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Formulas:
The basic electric formula is given below.
I = Q/t … (in Amperes)
Where:
- I = Current in amperes
- Q = Charge in Coulombs
- t = time in seconds
in DC Circuits
- I=V/R … (Ohm’s Law)
- I = P/V
- I = √P/R
in 1-Phase AC Circuits
- I = P / (V x Cosθ)
- I=(V/Z)
in 3-Phase AC Circuits
- I = P / √3 x V x Cosθ
Where:
- I = Current in Amperes (A)
- V = Voltage in Volts (V)
- P = Power in Watts (W)
- R = Resistance in Ohm (Ω)
- Z = Impedance = Resistance of AC Circuits
- Cosθ = Power Factor
Read More : How to Wire a Three-Phase Meter?
Key Differences
While voltage and current are closely related, there are several key differences between them:
- Definition: the measure of electric potential energy per unit charge, while current is the flow of electric charge through a circuit.
- Units: measured in volts, while current is measured in amperes.
- Symbol: typically represented by the symbol “V”, while current is represented by the symbol “I”.
- Effect on the Circuit: the force that drives current through a circuit, while current is the actual flow of electrons.
- Dependency: independent of the circuit, while current is dependent on the circuit’s resistance.
Applications
Understanding voltage and current is essential for many applications in electrical engineering. Some common applications of voltage and current include:
- Power Supplies: used to power electronic devices, such as smartphones, laptops, and televisions.
- Electric Motors: Current is used to power electric motors, which convert electrical energy into mechanical energy.
- Circuit Analysis: Voltage and current are both essential for analyzing and designing electrical circuits.
- Electrical Safety: Understanding voltage and current is important for electrical safety, as exposure to high voltages or currents can be dangerous or even fatal.
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Difference between Voltage and Current
| Sl. No. | Differentiating Property | Voltage | Current |
|---|---|---|---|
| 1 | Definition | Voltage, also called electromotive force, is simply the energy per unit charge. In other words, voltage is the difference in electric potential between two points. | Current is just the rate of flow of electric charge. In simple words, the current is the rate at which electric charge flows in a circuit at a particular point. |
| 2 | Unit | The SI unit of voltage is Volts (V).
Note: 1 Volt= 1 Joule/coulomb. |
The SI unit of current is Ampere (A).
Note: 1 Ampere = 1 coulomb/second. |
| 3 | Denotation | Voltage is denoted by “V”. | Current is denoted by “I”. |
| 4 | Measuring Instrument | Voltage can be measured by using a Voltmeter. | Current can be measured by using an Ammeter. |
| 5 | Inter-relation | Voltage is the cause of the current. | Current is the effect of the voltage i.e. current cannot flow without voltage. |
| 6 | Formula | One of the formulae to calculate voltage is:
V= Work done/Charge |
One of the formulae to calculate current is:
I= Charge/ Time |
| 7 | Loss | The loss of voltage occurs due to impedance. | The loss of current occurs due to the passive elements. |
| 8 | Field Created | Voltage creates an electrostatic field. | Current creates a magnetic field. |
| 9 | Change in a Series Connection | In a series connection, voltage changes i.e. it gets distributed over all the components. | In a series connection, the current remains the same through all the components. |
| 10 | Change in a Parallel Connection | In a parallel connection, the voltage remains the same across all the components. | In a parallel connection, current changes, i.e., gets distributed over all components. |
Read More : How to Wire Lights in Series?
FAQs
Define voltage.
Define current.
What is electric potential energy?
Define 1 Ampere.
What happens to the current when voltage is increased?
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