Electrical Energy Detailed Notes

Electrical devices are used worldwide to improve lives.
Examples include electric stoves, lights, and heaters.
These devices function due to the flow of electrons in electric circuits, enabled by a source of energy.
Electrical energy is the energy from the flow of electrons in an electric circuit, measured in joules (J).
Electrical devices convert electrical energy into other forms of energy to do work.
Electric lights convert electrical energy into light energy.
Motors convert electrical energy into motion.
While lightning is a natural form of electrical energy, harnessing it is not yet possible.
Other forms of energy can be transformed into electrical energy.

Batteries and electric generating stations are two main sources.
Batteries supply small amounts of electrical energy.
Electric generating stations deliver large amounts of electrical energy through transmission lines.
Alessandro Volta invented the first electric battery in 1799, providing a practical method for generating electricity.

Portable devices require portable sources of electrical energy.
An electric cell is a portable device that converts chemical energy into electrical energy.
It consists of two electrodes in a conducting solution called an electrolyte.
Electrodes are conductors, one easily positively charged and the other negatively charged.
Electrons flow from one electrode to the other when connected in a circuit.
Electrons in the electrolyte are repelled by the negative electrode and attracted to the positive electrode.
In science, a "battery" refers to two or more electric cells in combination.

Primary cells cannot be recharged because the chemical reactions are not reversible.
Examples include zinc chloride, alkaline, and lithium cells.
Primary cells have a shelf life of up to five years when not in use.

Secondary cells can be recharged and reused multiple times.
Electrical energy from a wall outlet reverses the chemical reactions in a secondary cell.
Examples include lead-acid batteries and nickel metal hydride (NiMH) batteries.
They have a shelf life of six months.
Lithium secondary cells are the most expensive but have a shelf life of up to one year.

All electric cells contain toxic chemicals and should be properly recycled.
The types of electrodes and chemicals in the electrolyte affect the strength and duration of the charge flow.

Like charges repel, and opposite charges attract. This principle is crucial for understanding electron flow within cells.

An experiment to create an electric cell using a copper penny, metal paper clip, and a pickle as the conducting solution.
The battery tester indicates electron flow through the pickle cell.
Replacing the electrodes with two pennies or two paper clips may affect the cell's performance.
Using a plastic paper clip will not work because plastic is not conductive.
Other fruits or vegetables may work as electrolytes.

Sir William Grove invented the first fuel cell in 1839.
Fuel cell: a special kind of electric cell through which a continuous supply of chemicals is pumped as the cell operates, and waste products are removed.
This allows fuel cells to operate longer than conventional electric cells.
Hydrogen fuel cells produce electrical energy by converting hydrogen and oxygen into water.
Fuel Cell Vehicles (FCVs) use electric motors powered by fuel cells.
These vehicles extract electricity from hydrogen fuel quietly and efficiently and produce no tailpipe emissions.
The Canadian government is developing a fuel cell vehicle program in Vancouver, British Columbia.

While FCVs have no direct negative impact on the environment, producing hydrogen fuel involves energy-intensive processes.
Hydrogen is often extracted from fossil fuels, which requires energy and contributes to pollution and climate change.
Fuel cells are not as "green" as they may seem because of the energy required to produce hydrogen.
Fuel cells are compact and lightweight, making them useful in remote locations, such as in the U.S. space program.

Electrical energy is the energy associated with the flow of electrons in a circuit, measured in joules (J).
Batteries are a source of electrical energy and are useful for portable electrical devices, while electric generating stations provide large amounts of electrical energy.
Alkaline batteries are an example of primary cells.
Secondary cells can be recharged and reused many times before being recycled.
Fuel cells use continuous supply of chemicals, such as hydrogen and oxygen, to provide electrical energy.