Resistance is measured in Ohms. The Ohm is often represented by the omega symbol: Ω. The symbol for resistance is a zigzag line as shown below. The letter "R" is used in equations.
The ampere, symbol A, is the SI unit of electric current.
The henry (symbol: H) is the SI derived unit of electrical inductance. The unit is named after Joseph Henry (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same time as Michael Faraday (1791–1867) in England.
What is Ohm's Law? Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. R depends on the dimensions of the conductor and also on the material of the conductor. Its SI unit is Ohm (Ω).
Ohm's law, description of the relationship between current, voltage, and resistance. The amount of steady current through a large number of materials is directly proportional to the potential difference, or voltage, across the materials. Ohm's law may be expressed mathematically as V/I = R.
The relationship between current, voltage and resistance is expressed by Ohm's Law. This states that the current flowing in a circuit is directly proportional to the applied voltage and inversely proportional to the resistance of the circuit, provided the temperature remains constant.
Ohms Law and Power
- To find the Voltage, ( V ) [ V = I x R ] V (volts) = I (amps) x R (Ω)
- To find the Current, ( I ) [ I = V ÷ R ] I (amps) = V (volts) ÷ R (Ω)
- To find the Resistance, ( R ) [ R = V ÷ I ] R (Ω) = V (volts) ÷ I (amps)
- To find the Power (P) [ P = V x I ] P (watts) = V (volts) x I (amps)
Ohm defines the unit of resistance of "1 Ohm" as the resistance between two points in a conductor where the application of 1 volt will push 1 ampere, or 6.241×10^18 electrons. This value is usually represented in schematics with the greek letter "Ω", which is called omega, and pronounced "ohm".
What is Ohm's Law?
| Quantity | Ohm's Law symbol | Unit of measure (abbreviation) |
|---|
| Voltage | E | Volt (V) |
| Current | I | Ampere, amp (A) |
| Resistance | R | Ohm (Ω) |
"Ohm" is a unit of an electric circuit that is defined as the electrical resistance between two points of a conductor when a constant potential difference of one volt, applied to these points, produces in the conductor a current of one ampere, the conductor not being the seat of any electromotive force.
This brings us back to Georg Ohm. Ohm defines the unit of resistance of “1 Ohm” as the resistance between two points in a conductor where the application of 1 volt will push 1 ampere, or 6.241×1018 electrons.
A coil with many circular close turns of insulated copper wire (like a cylinder as shown above) is a solenoid. One end of such a solenoid behaves like the north pole and the other as a south pole. Therefore magnetic field due to current in the solenoid is similar to a bar magnet.
Answer: Resistance is the property of a conductor, which determines the quantity of current that passes through it when a potential difference is applied across it. A resistor is a electrical componet with a predetermined electrical resistance, like 1 ohm, 10 ohms 100 ohms 10000 ohms etc.
Rheostat is an electric device used as a variable resistance, like the regulator of the fan. It is used to change the electric resistance in the electric circuit. UsuallyRheostat consists of a coil of wire with a terminal at one end and a sliding contact that moves along the coil to tap off the current.
An electric current flows when electrons move through a conductor, such as a metal wire. The moving electrons can collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance.
