How do objects become negatively charged?

Objects become negatively charged by gaining extra electrons.

In GCSE Physics, it's important to understand that all matter is made up of atoms, which consist of protons, neutrons, and electrons. Protons have a positive charge, electrons have a negative charge, and neutrons are neutral. Normally, an atom has an equal number of protons and electrons, making it electrically neutral.

However, when an object gains extra electrons, it becomes negatively charged. This can happen through various processes, such as friction, conduction, or induction. For example, when you rub a balloon on your hair, electrons are transferred from your hair to the balloon. This transfer of electrons leaves the balloon with more electrons than protons, giving it a negative charge.

In conduction, a negatively charged object can transfer some of its extra electrons to a neutral object when they come into contact. This process also results in the neutral object becoming negatively charged. Induction, on the other hand, involves bringing a charged object close to a neutral object without direct contact. The presence of the charged object causes a redistribution of electrons within the neutral object, leading to a temporary or permanent charge.

Understanding these processes helps explain everyday phenomena, such as static electricity. For instance, when you walk across a carpet and then touch a metal doorknob, you might feel a small shock. This happens because your body has gained extra electrons from the carpet, making you negatively charged. When you touch the doorknob, the electrons quickly move to the metal, neutralising the charge and causing the shock.

By studying these concepts, you can better understand how and why objects become negatively charged, which is a fundamental aspect of electricity and magnetism in physics.