Electricity

Electricity in the home powers appliances and lighting through circuits connected to the electrical grid. It's generated at power stations, travels through electricity lines, and is controlled by transformers to ensure safety and demand for everyday use. Understanding electricity helps us use appliances efficiently and safely in our homes.

Equations on this page:
Energy transferred

What is the difference between AC and DC electricity?

AC stands for alternating current. It is a type of electrical current where the flow of electrons constantly reverses direction many times per second. AC electricity is commonly used in homes, businesses, and industries for powering appliances, lighting, and machinery. One of the main advantages of AC electricity is that it can be easily transmitted over long distances using transformers, which allow for efficient voltage conversion and distribution.

DC stand for direct current. It is a type of electrical current where the flow of electrons remains constant in one direction. In a DC circuit, the flow of electrons travels from the negative terminal to the positive terminal of the voltage source. DC electricity is commonly used in batteries and electronic devices. One of the main advantages of DC electricity is its ability to provide a steady and stable voltage, making it suitable for sensitive electronic equipment.

What is static electricity?

Static electricity is where electric charges build up on the surface of an object due to friction or contact with another object. These charges can remain in place without flowing away, hence the term "static."

Atoms are made up of positively charged protons, negatively charged electrons, and neutral neutrons. Normally, atoms have an equal number of protons and electrons, so they are electrically neutral. When certain materials rub against each other, such as a comb through hair or a balloon against clothing, electrons can be transferred from one material to another. This transfer creates an imbalance of charges, leading to one material becoming positively charged and the other negatively charged.

Attraction and repulsion

Objects that acquire an excess of electrons become negatively charged, while those that lose electrons become positively charged. Negatively charged objects are attracted to positively charged objects, while similarly charged objects (negative to negative, or positive to positive) repel each other. For example, a statically charged balloon can stick to a wall or cling to hair due to the attraction between the charged balloon and the oppositely charged surface.

What are electric fields?

Electric fields are invisible areas surrounding charged objects where electric forces can influence the behaviour of other charged objects nearby. When a charged object is placed in an electric field, it experiences a force due to the interaction with the electric field. The direction of the force depends on the charge of the object and the direction of the electric field. Positively charged objects experience a force in the direction of the electric field, while negatively charged objects experience a force opposite to the direction of the field.

Electric fields are represented by imaginary lines called electric field lines. These lines indicate the direction of the force that a positive test charge would experience if placed in the field. Electric field lines always point away from positively charged objects and towards negatively charged objects. The density of field lines represents the strength of the electric field, with denser lines indicating stronger fields.

The strength of an electric field at a point is measured by the force experienced by a unit of positive charge placed at that point. The unit of electric field strength is volts per meter (V/m). This means that one volt of electric potential difference exists across one meter of distance in the electric field.

Links for Learning

Grade Gorilla: Quizzes
GCSE.com: Physics Formulas
BBC Bitesize: Electricity
BBC Bitesize: Mains electricity