Final answer:
A net charge on an object can be caused by gaining or losing electrons, and this can occur through friction, contact, conduction, or induction. When an object gains electrons, it becomes negatively charged, making another object positively charged due to the loss of electrons, in adherence to the law of conservation of charge.
Step-by-step explanation:
There are various ways that a net charge can build up on an object or move from one object to another. Typically, objects are electrically neutral when they have an equal amount of positive and negative charge. However, an object can become electrically charged by gaining or losing electrons. If an object has gained electrons, it becomes negatively charged, resulting in an excess of electrons. Conversely, if it loses electrons, it becomes positively charged due to a depletion of electrons. This transfer can occur in several ways:
- Friction: Rubbing two materials together can cause electrons to be transferred from one object to another.
- Contact: Simply touching an object with a net charge can transfer charges.
- Conduction: Charge movement in conducting materials.
- Induction: Redistributing charges within an object, without direct contact.
When electrons are transferred from a neutral object, the once neutral object becomes positively charged, as it has lost some of its negative charge. Electric charge is a conserved quantity, which means it cannot be created or destroyed, only transferred. Thus, whenever an object gains electrons and becomes negatively charged, another object must correspondingly become positively charged.
According to the law of conservation of charge, the net charge of a closed system remains constant. However, in an open system, charge can be transferred to or from the system, which will change the system's net charge but still obey the overall conservation law.