Electric Charge and Law of Conservation of Charge

Summary

This video explains the principles of energy and electric charge conservation. It starts by discussing how energy is transferred and conserved in the universe, stating that energy cannot be created or destroyed, only transformed. The concept of electric charge follows similarly, with protons and electrons carrying opposite charges. The law of conservation of electric charge asserts that the total charge in a system remains constant. The video also covers charging through an example where rubbing a plastic comb with cloth transfers electrons, creating a negative charge on the comb. Finally, it explores how electric charge dissipates through interactions with water molecules in the air.

Takeaways

• 😀 Energy in an isolated system remains constant, meaning it cannot be created or destroyed, only transformed.
• 😀 Similar to energy, electric charge is also conserved and can be transferred between systems.
• 😀 Electric charge is a property of subatomic particles like protons and electrons, with protons carrying positive charge and electrons carrying negative charge.
• 😀 Unlike charges (protons and electrons) attract each other, while like charges (two protons or two electrons) repel each other.
• 😀 The quantity of electric charge carried by protons and electrons is equal but opposite in sign.
• 😀 Electric charge can transfer from one system to another, and the total quantity of electric charge in the universe remains constant, as per the law of conservation of electric charge.
• 😀 Whenever electric charge is transferred, the amount of charge lost by one system is gained by another, ensuring that the net charge in a process is always zero.
• 😀 Charging is the process of transferring electric charge between systems or objects, with electrons being the particles that move in solids, not protons.
• 😀 In a common experiment, rubbing a plastic comb with a cloth results in the transfer of electrons, giving the comb a negative charge and the cloth a positive charge.
• 😀 The net charge of two objects involved in charging remains zero, as the total amount of charge remains conserved.
• 😀 Over time, objects that gain charge will lose it, with charge transferring to air molecules, like water molecules, which have a partial positive charge that attracts electrons.

Q & A

What does the conservation of energy state?

The conservation of energy states that the total quantity of energy in an isolated system always remains constant. Energy cannot be destroyed or created; it can only be transformed from one type to another or transferred between systems.

What is the relationship between electric charge and the conservation of energy?

Just like energy, electric charge is conserved. This means that electric charge can transfer from one system to another, but the total amount of charge in an isolated system remains constant.

What are the three types of subatomic particles that make up an atom?

The three types of subatomic particles that make up an atom are protons, neutrons, and electrons. Protons carry a positive electric charge, neutrons do not carry any charge, and electrons carry a negative electric charge.

Why do protons and electrons attract each other?

Protons and electrons attract each other because they have opposite electric charges: protons are positively charged, while electrons are negatively charged. Opposite charges attract.

What does the law of conservation of electric charge state?

The law of conservation of electric charge states that the total electric charge in an isolated system remains constant. Whenever electric charge transfers out of a system, the same quantity of charge must be gained by the surroundings, ensuring the net charge remains zero.

How does charging occur in solids?

In solids, protons are fixed in place and cannot move, so the transfer of electric charge involves the movement of electrons. When an object gains or loses electrons, it becomes charged.

What happens when a plastic comb is rubbed with a cloth?

When a plastic comb is rubbed with a cloth, electrons transfer from the cloth to the comb. As a result, the comb gains a negative charge, and the cloth gains a positive charge.

What is the effect of rubbing a comb with a cloth on the charge of the objects involved?

Rubbing a comb with a cloth transfers electrons to the comb, causing the comb to become negatively charged, while the cloth becomes positively charged. The total charge of the system remains zero due to the law of conservation of electric charge.

Why does a negatively charged comb attract pieces of paper with a positive charge?

A negatively charged comb attracts pieces of paper with a positive charge because opposite charges attract. The comb, with its negative charge, attracts the positively charged paper.

Why does the comb eventually lose its electric charge over time?

The comb loses its electric charge over time because electrons transfer from the comb to the water molecules in the air. Water molecules, which have a partial positive charge on the oxygen atom, attract the electrons from the comb, leading it to lose its negative charge.