An ohm is the unit of electrical resistance. According to the reference, the ohm is a measurement of resistance between two points of a conductor when a constant potential difference of one volt (V) is applied to those points and a current of one ampere (A) is produced. It is the equivalent of one volt per ampere (V/A).
Understanding Resistance
Think of resistance like friction in a pipe. The more friction (resistance), the harder it is to push water (current) through the pipe, given the same pressure (voltage).
Key Concepts
- Voltage (V): The electrical "pressure" that drives current through a circuit, measured in volts.
- Current (I): The flow of electrical charge, measured in amperes (amps).
- Resistance (R): The opposition to the flow of current, measured in ohms (Ω).
Ohm's Law
The relationship between voltage, current, and resistance is defined by Ohm's Law:
V = I * R
Where:
- V = Voltage (in volts)
- I = Current (in amperes)
- R = Resistance (in ohms)
This can be rearranged to solve for resistance:
R = V / I
Practical Examples
- A resistor in an electronic circuit might have a resistance of 100 ohms.
- A light bulb filament might have a resistance of a few ohms when it's hot.
- A long length of wire could have a very small resistance, perhaps a fraction of an ohm.
Calculating Resistance
Let's say you have a circuit with a 12V power supply and a current of 2A flowing through a resistor. To find the resistance, you would use Ohm's Law:
R = V / I
R = 12V / 2A
R = 6 ohms
Visualizing Resistance
| Term | Analogy | Electrical Property | Unit |
|---|---|---|---|
| Voltage | Water pressure | Potential Difference | Volts |
| Current | Water flow | Electron Flow | Amperes |
| Resistance | Pipe diameter (narrower = higher resistance) | Opposition to Flow | Ohms |
