Conversion of Physical Quantities: Electrical Quantities
Electricity is a ubiquitous phenomenon that powers countless devices and technologies in our lives. Understanding electrical quantities and their interrelationships is crucial for engineers, technicians, hobbyists, and anyone interested in electronics.
Introduction to Electrical Quantities
Electrical quantities refer to measurable attributes of electric circuits, such as voltage, current, resistance, capacitance, inductance, and power. Each quantity is defined and measured using specific units.
List of Common Electrical Quantities
- Voltage (V)
- Definition: Potential difference between two points in an electric circuit.
- Unit: Volt (V)
- Named After: Count Alessandro Volta, inventor of the battery.
- Current (I)
- Definition: Flow rate of electric charge.
- Unit: Ampere (A)
- Named After: André-Marie Ampère, pioneer in electrodynamics.
- Resistance (R)
- Definition: Opposition to the flow of electric current.
- Unit: Ohm (Ω)
- Named After: Georg Simon Ohm, discoverer of Ohm’s Law.
- Capacitance (C)
- Definition: Ability to store electric charge.
- Unit: Farad (F)
- Named After: Michael Faraday, renowned scientist in electromagnetic induction.
- Inductance (L)
- Definition: Property of a conductor that opposes changes in current.
- Unit: Henry (H)
- Named After: Joseph Henry, early researcher in electromagnetism.
- Power (P)
- Definition: Rate at which energy is transferred or transformed.
- Unit: Watt (W)
- Named After: James Watt, developer of the steam engine.
- Frequency (f)
- Definition: Number of cycles per second in alternating current.
- Unit: Hertz (Hz)
- Named After: Heinrich Rudolf Hertz, who proved existence of radio waves.
- Impedance (Z)
- Definition: Total opposition to AC current, combining resistance and reactance.
- Unit: Ohm (Ω)
- Magnetic Flux Density (B)
- Definition: Strength of magnetic field passing through a given area.
- Unit: Tesla (T)
- Named After: Nikola Tesla, famous inventor and electrical engineer.
- Charge (Q)
- Definition: Quantity of electricity carried by particles.
- Unit: Coulomb (C)
- Named After: Charles-Augustin de Coulomb, founder of Coulomb’s law.
Conclusion
Familiarity with electrical quantities and their conversions enables efficient troubleshooting, design, and optimization of electronic components and systems. By understanding these fundamental concepts, readers can approach any electrical project with greater confidence and skill.
| Quantity | Symbol | Unit | Description |
| Voltage | V | Volt (V) | Difference in electric potential between two points |
| Current | I | Ampere (A) | Rate of flow of electric charge |
| Resistance | R | Ohm (Ω) | Opposition to the passage of electric current |
| Capacitance | C | Farad (F) | Capacity to store electric charge |
| Inductance | L | Henry (H) | Ability to resist changes in current |
| Power | P | Watt (W) | Rate of energy transfer or transformation |
| Frequency | f | Hertz (Hz) | Number of oscillations per second in alternating current |
| Impedance | Z | Ohm (Ω) | Total opposition to AC current (includes resistance and reactance) |
| Magnetic Field | B | Tesla (T) | Strength of magnetic flux density |
| Charge | Q | Coulomb (C) | Quantity of electric charge carried by particles |
| Energy | E | Joule (J) | Measure of total work done by or on a system |
| Reactance | X | Ohm (Ω) | Component of impedance that arises from capacitive or inductive elements |
| Susceptance | B | Siemens (S) | Reciprocal of reactance, indicating susceptibility to AC currents |
| Admittance | Y | Siemens (S) | Reciprocal of impedance, indicates ease of AC current flow |
| Resistivity | ρ | Ω·m | Material-specific resistance per unit length |
| Permittivity | ε | F/m | Ability of a material to permit electric field lines |
| Permeability | μ | H/m | Degree to which a medium supports formation of a magnetic field |
FAQs on Conversion of Physical Quantities: Electrical Quantities
What is the difference between amps and volts?
Amps measure the flow of electric current, while volts measure the electric potential difference (voltage).
How do I convert ohms to megohms?
Multiply ohms by 10−610−6. For example, 1,000,000 ohms = 1 megohm.
What is the relation between watts and volts?
Watts (power) equals volts (voltage) multiplied by amps (current): P=V⋅IP=V⋅I.
How many volts are in a kilovolt?
There are 1,000 volts in 1 kilovolt.
What is the definition of ohm?
Resistance offered by a conductor carrying 1 amp of current when subjected to a potential difference of 1 volt.
How do I convert microfarads to farads?
Divide microfarads by 106106. For example, 1,000,000 microfarads = 1 farad.
What is the relationship between henries and microhenries?
There are 1,000,000 microhenries in 1 henry.
How do I convert coulombs to ampere-hours?
Divide coulombs by 3,600. For example, 3,600 coulombs = 1 ampere-hour.
What is the difference between wattage and power?
Wattage is a measure of power—the rate at which energy is produced or consumed.
How do I convert joules to kilojoules?
Divide joules by 1,000. For example, 1,000 joules = 1 kilojoule.
What is the formula for calculating resistance?
Using Ohm’s Law: R=VIR=IV, where RR is resistance, VV is voltage, and II is current.
How do I convert horsepower to watts?
Multiply horsepower by 745.7. For example, 1 horsepower = 745.7 watts.
What is the meaning of impedance?
Impedance combines resistance and reactance, affecting the overall opposition to AC current flow.
How do I convert amps to milliamps?
Multiply amps by 1,000. For example, 1 amp = 1,000 milliamps.
What is the unit of frequency?
Frequency is measured in hertz (Hz), representing cycles per second.
How do I convert watts to kilowatts?
Divide watts by 1,000. For example, 1,000 watts = 1 kilowatt.
What is the symbol for voltage?
The symbol for voltage is V.
How do I convert kelvins to volts?
There is no direct conversion between kelvins (temperature) and volts (electric potential). These are fundamentally different physical quantities.
What is the function of a resistor?
Resistors limit the flow of electric current in a circuit, controlling voltage drops and protecting sensitive components.
How do I convert microamperes to amperes?
Divide microamperes by 106106. For example, 1,000,000 microamperes = 1 ampere.