## Ohm – Unit of Resistance

The unit of resistance is the ohm (symbolized by the Greek letter omega, Ω). It is named after Georg Simon Ohm, a German physicist who discovered Ohm’s law, which describes the relationship between electrical current, voltage, and resistance in a circuit. One ohm of resistance is defined as the amount of resistance that allows a current of one ampere to flow with a voltage of one volt.

Resistance arises due to the interactions between electrons and the atoms or molecules that make up the material. When an electric current flows through a material, the electrons collide with these atoms or molecules, causing the electrons to lose energy and reducing the flow of current.

The resistance of a material depends on several factors, including its length, cross-sectional area, and the material’s resistivity, which is a measure of how strongly the material opposes the flow of current. Some materials, such as metals, have low resistance and are good conductors of electricity, while other materials, such as rubber or glass, have high resistance and are insulators.

## Resistance of various home devices

Here are five examples of resistance in ohms of various home devices:

- Incandescent light bulb: The resistance of an incandescent light bulb varies depending on its wattage and voltage. For example, a 60-watt bulb designed to work with a 120-volt power supply will have a resistance of approximately 240 ohms.
- Electric heater: An electric heater typically has a resistance ranging from 10 ohms to several hundred ohms, depending on its size and power rating. For example, a small 1,500-watt electric heater designed to operate on a 120-volt power supply will have a resistance of approximately 10 ohms.
- Electric stove: The heating elements in an electric stove typically have resistances ranging from 10 to 100 ohms, depending on their size and power rating. For example, a typical 8-inch burner on an electric stove may have a resistance of around 20 ohms.
- Electric iron: An electric iron typically has a resistance ranging from 10 to 30 ohms, depending on its size and power rating. For example, a typical 1,500-watt electric iron designed to operate on a 120-volt power supply will have a resistance of approximately 10 ohms.
- Electric toaster: The heating elements in an electric toaster typically have resistances ranging from 10 to 50 ohms, depending on their size and power rating. For example, a typical two-slice toaster may have heating elements with a combined resistance of around 20 ohms.